Release 2.5.1

Bumps [urllib3](https://github.com/urllib3/urllib3) from 2.5.0 to 2.6.0.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](https://github.com/urllib3/urllib3/compare/2.5.0...2.6.0)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-version: 2.6.0
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

CHANGES.md

@@ -1,5 +1,16 @@
 # Microdot change log
 
+**Release 2.5.1** - 2025-12-21
+
+- CSRF: accept cross-site request if origin is in the CORS allowed origin list ([commit](https://github.com/miguelgrinberg/microdot/commit/ba6893ca0fb3c3dd18cf934f8eee893cc2a10daa))
+
+**Release 2.5.0** - 2025-12-21
+
+- CSRF protection [#335](https://github.com/miguelgrinberg/microdot/issues/335) ([commit](https://github.com/miguelgrinberg/microdot/commit/0bae4c9477e9fdb231d1979cc6ed26c31e12b1aa))
+- Added support for ASGI lifespan events [#322](https://github.com/miguelgrinberg/microdot/issues/322) ([commit](https://github.com/miguelgrinberg/microdot/commit/f128b3ded45ccd418a00d199769240342a613b5e))
+- Added `scheme` and `route` attributes to the request object ([commit](https://github.com/miguelgrinberg/microdot/commit/1c7020ca1a3e5a6a1549dc52de38a0b7fd0a439a))
+- Added `Login.get_current_user()` helper method ([commit](https://github.com/miguelgrinberg/microdot/commit/053b8a81380fcdf285592a32e6b590ee50b7d048))
+
 **Release 2.4.0** - 2025-11-08
 
 - SSE: Add support for the retry command and keepalive comments ([commit](https://github.com/miguelgrinberg/microdot/commit/d0808efa6b32e00992596f1bb3d4c3a372df2168))

README.md

@@ -19,24 +19,15 @@ async def index(request):
 app.run()
 ```
 
-## Migrating to Microdot 2
-
-Version 2 of Microdot incorporates feedback received from users of earlier
-releases, and attempts to improve and correct some design decisions that have
-proven to be problematic.
-
-For this reason most applications built for earlier versions will need to be
-updated to work correctly with Microdot 2. The
-[Migration Guide](https://microdot.readthedocs.io/en/stable/migrating.html)
-describes the backwards incompatible changes that were made.
-
 ## Resources
 
 - [Change Log](https://github.com/miguelgrinberg/microdot/blob/main/CHANGES.md)
 - Documentation
     - [Latest](https://microdot.readthedocs.io/en/latest/)
     - [Stable (v2)](https://microdot.readthedocs.io/en/stable/)
-    - [Legacy (v1)](https://microdot.readthedocs.io/en/v1/) ([Code](https://github.com/miguelgrinberg/microdot/tree/v1))
+- Legacy (v1)
+    - [Code](https://github.com/miguelgrinberg/microdot/tree/v1)
+    - [Documentation](https://microdot.readthedocs.io/en/v1/)
 
 ## Roadmap
 
@@ -45,12 +36,8 @@ MicroPython and CPython:
 
 - Authentication support, similar to [Flask-Login](https://github.com/maxcountryman/flask-login) for Flask (**Added in version 2.1**)
 - Support for forms encoded in `multipart/form-data` format (**Added in version 2.2**)
+- CSRF protection extension (**Added in version 2.5**)
+- Pub/sub mini-framework for WebSocket and SSE
 - OpenAPI integration, similar to [APIFairy](https://github.com/miguelgrinberg/apifairy) for Flask
 
-In addition to the above, the following extensions are also under consideration,
-but only for CPython:
-
-- Database integration through [SQLAlchemy](https://github.com/sqlalchemy/sqlalchemy)
-- Socket.IO support through [python-socketio](https://github.com/miguelgrinberg/python-socketio)
-
 Do you have other ideas to propose? Let's [discuss them](https://github.com/:miguelgrinberg/microdot/discussions/new?category=ideas)!

docs/api.rst

@@ -1,95 +0,0 @@
-API Reference
-=============
-
-Core API
---------
-
-.. autoclass:: microdot.Microdot
-   :members:
-
-.. autoclass:: microdot.Request
-   :members:
-
-.. autoclass:: microdot.Response
-   :members:
-
-.. autoclass:: microdot.URLPattern
-   :members:
-
-Multipart Forms
----------------
-
-.. automodule:: microdot.multipart
-   :members:
-
-WebSocket
----------
-
-.. automodule:: microdot.websocket
-   :members:
-
-Server-Sent Events (SSE)
-------------------------
-
-.. automodule:: microdot.sse
-   :members:
-
-Templates (uTemplate)
----------------------
-
-.. automodule:: microdot.utemplate
-   :members:
-
-Templates (Jinja)
------------------
-
-.. automodule:: microdot.jinja
-   :members:
-
-User Sessions
--------------
-
-.. automodule:: microdot.session
-   :members:
-
-Authentication
---------------
-
-.. automodule:: microdot.auth
-   :inherited-members:
-   :special-members: __call__
-   :members:
-
-User Logins
------------
-
-.. automodule:: microdot.login
-   :inherited-members:
-   :special-members: __call__
-   :members:
-
-Cross-Origin Resource Sharing (CORS)
-------------------------------------
-
-.. automodule:: microdot.cors
-   :members:
-
-Test Client
------------
-
-.. automodule:: microdot.test_client
-   :members:
-
-ASGI
-----
-
-.. autoclass:: microdot.asgi.Microdot
-   :members:
-   :exclude-members: shutdown, run
-
-WSGI
-----
-
-.. autoclass:: microdot.wsgi.Microdot
-   :members:
-   :exclude-members: shutdown, run

docs/api/asgi.rst

@@ -0,0 +1,6 @@
+ASGI
+----
+
+.. autoclass:: microdot.asgi.Microdot
+   :members:
+   :exclude-members: shutdown, run

docs/api/auth.rst

@@ -0,0 +1,7 @@
+Authentication
+--------------
+
+.. automodule:: microdot.auth
+   :inherited-members:
+   :special-members: __call__
+   :members:

docs/api/cors.rst

@@ -0,0 +1,5 @@
+Cross-Origin Resource Sharing (CORS)
+------------------------------------
+
+.. automodule:: microdot.cors
+   :members:

docs/api/csrf.rst

@@ -0,0 +1,5 @@
+Cross-Site Request Forgery (CSRF) Protection
+--------------------------------------------
+
+.. automodule:: microdot.csrf
+   :members:

docs/api/index.rst

@@ -0,0 +1,21 @@
+API Reference
+=============
+
+.. toctree::
+   :maxdepth: 1
+
+   microdot
+   multipart
+   websocket
+   sse
+   utemplate
+   jinja
+   sessions
+   auth
+   login
+   cors
+   csrf
+   test_client
+   asgi
+   wsgi
+

docs/api/jinja.rst

@@ -0,0 +1,5 @@
+Templates (Jinja)
+-----------------
+
+.. automodule:: microdot.jinja
+   :members:

docs/api/login.rst

@@ -0,0 +1,7 @@
+User Logins
+-----------
+
+.. automodule:: microdot.login
+   :inherited-members:
+   :special-members: __call__
+   :members:

docs/api/microdot.rst

@@ -0,0 +1,14 @@
+Core API
+--------
+
+.. autoclass:: microdot.Microdot
+   :members:
+
+.. autoclass:: microdot.Request
+   :members:
+
+.. autoclass:: microdot.Response
+   :members:
+
+.. autoclass:: microdot.URLPattern
+   :members:

docs/api/multipart.rst

@@ -0,0 +1,5 @@
+Multipart Forms
+---------------
+
+.. automodule:: microdot.multipart
+   :members:

docs/api/sessions.rst

@@ -0,0 +1,5 @@
+User Sessions
+-------------
+
+.. automodule:: microdot.session
+   :members:

docs/api/sse.rst

@@ -0,0 +1,5 @@
+Server-Sent Events (SSE)
+------------------------
+
+.. automodule:: microdot.sse
+   :members:

docs/api/test_client.rst

@@ -0,0 +1,5 @@
+Test Client
+-----------
+
+.. automodule:: microdot.test_client
+   :members:

docs/api/utemplate.rst

@@ -0,0 +1,5 @@
+Templates (uTemplate)
+---------------------
+
+.. automodule:: microdot.utemplate
+   :members:

docs/api/websocket.rst

@@ -0,0 +1,5 @@
+WebSocket
+---------
+
+.. automodule:: microdot.websocket
+   :members:

docs/api/wsgi.rst

@@ -0,0 +1,6 @@
+WSGI
+----
+
+.. autoclass:: microdot.wsgi.Microdot
+   :members:
+   :exclude-members: shutdown, run

docs/conf.py

@@ -46,7 +46,8 @@ exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'alabaster'
+html_theme = 'furo'
+html_title = 'Microdot'
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
@@ -58,12 +59,6 @@ html_css_files = [
 ]
 
 html_theme_options = {
-    'github_user': 'miguelgrinberg',
-    'github_repo': 'microdot',
-    'github_banner': True,
-    'github_button': True,
-    'github_type': 'star',
-    'fixed_sidebar': True,
 }
 
 autodoc_default_options = {

docs/contributing.rst

@@ -0,0 +1,7 @@
+Contributing
+------------
+
+Thank you for your interest in Microdot!
+
+Please visit the `GitHub repository <https://github.com/miguelgrinberg/microdot>`_
+to learn about the project and find open issues and pull requests.

docs/extensions.rst

@@ -1,778 +0,0 @@
-Core Extensions
----------------
-
-Microdot is a highly extensible web application framework. The extensions
-described in this section are maintained as part of the Microdot project in
-the same source code repository.
-
-Multipart Forms
-~~~~~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     -  | `multipart.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/multipart.py>`_
-        | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
-
-   * - Required external dependencies
-     - | None
-
-   * - Examples
-     - | `formdata.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/uploads/formdata.py>`_
-
-The multipart extension handles multipart forms, including those that have file
-uploads.
-
-The :func:`with_form_data <microdot.multipart.with_form_data>` decorator
-provides the simplest way to work with these forms. With this decorator added
-to the route, whenever the client sends a multipart request the
-:attr:`request.form <microdot.Request.form>` and
-:attr:`request.files <microdot.Request.files>` properties are populated with
-the submitted data. For form fields the field values are always strings. For
-files, they are instances of the
-:class:`FileUpload <microdot.multipart.FileUpload>` class.
-
-Example::
-
-    from microdot.multipart import with_form_data
-
-    @app.post('/upload')
-    @with_form_data
-    async def upload(request):
-        print('form fields:', request.form)
-        print('files:', request.files)
-
-One disadvantage of the ``@with_form_data`` decorator is that it has to copy
-any uploaded files to memory or temporary disk files, depending on their size.
-The :attr:`FileUpload.max_memory_size <microdot.multipart.FileUpload.max_memory_size>`
-attribute can be used to control the cutoff size above which a file upload
-is transferred to a temporary file.
-
-A more performant alternative to the ``@with_form_data`` decorator is the
-:class:`FormDataIter <microdot.multipart.FormDataIter>` class, which iterates
-over the form fields sequentially, giving the application the option to parse
-the form fields on the fly and decide what to copy and what to discard. When
-using ``FormDataIter`` the ``request.form`` and ``request.files`` attributes
-are not used.
-
-Example::
-
-
-    from microdot.multipart import FormDataIter
-
-    @app.post('/upload')
-    async def upload(request):
-        async for name, value in FormDataIter(request):
-            print(name, value)
-
-For fields that contain an uploaded file, the ``value`` returned by the
-iterator is the same ``FileUpload`` instance. The application can choose to
-save the file with the :meth:`save() <microdot.multipart.FileUpload.save>`
-method, or read it with the :meth:`read() <microdot.multipart.FileUpload.read>`
-method, optionally passing a size to read it in chunks. The
-:meth:`copy() <microdot.multipart.FileUpload.copy>` method is also available to
-apply the copying logic used by the ``@with_form_data`` decorator, which is
-inefficient but allows the file to be set aside to be processed later, after
-the remaining form fields.
-
-WebSocket
-~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     -  | `websocket.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/websocket.py>`_
-        | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
-
-   * - Required external dependencies
-     - | None
-
-   * - Examples
-     - | `echo.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo.py>`_
-
-The WebSocket extension gives the application the ability to handle WebSocket
-requests. The :func:`with_websocket <microdot.websocket.with_websocket>`
-decorator is used to mark a route handler as a WebSocket handler. Decorated
-routes receive a WebSocket object as a second argument. The WebSocket object
-provides ``send()`` and ``receive()`` asynchronous methods to send and receive
-messages respectively.
-
-Example::
-
-    from microdot.websocket import with_websocket
-
-    @app.route('/echo')
-    @with_websocket
-    async def echo(request, ws):
-        while True:
-            message = await ws.receive()
-            await ws.send(message)
-
-To end the WebSocket connection, the route handler can exit, without returning
-anything::
-
-    @app.route('/echo')
-    @with_websocket
-    async def echo(request, ws):
-        while True:
-            message = await ws.receive()
-            if message == 'exit':
-                break
-            await ws.send(message)
-        await ws.send('goodbye')
-
-If the client ends the WebSocket connection from their side, the route function
-is cancelled. The route function can catch the ``CancelledError`` exception
-from asyncio to perform cleanup tasks::
-
-    @app.route('/echo')
-    @with_websocket
-    async def echo(request, ws):
-        try:
-            while True:
-                message = await ws.receive()
-                await ws.send(message)
-        except asyncio.CancelledError:
-            print('Client disconnected!')
-
-Server-Sent Events
-~~~~~~~~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     -  | `sse.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/sse.py>`_
-        | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
-
-   * - Required external dependencies
-     - | None
-
-   * - Examples
-     - | `counter.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/sse/counter.py>`_
-
-The Server-Sent Events (SSE) extension simplifies the creation of a streaming
-endpoint that follows the SSE web standard. The :func:`with_sse <microdot.sse.with_sse>`
-decorator is used to mark a route as an SSE handler. Decorated routes receive
-an SSE object as second argument. The SSE object provides a ``send()``
-asynchronous method to send an event to the client.
-
-Example::
-
-    from microdot.sse import with_sse
-
-    @app.route('/events')
-    @with_sse
-    async def events(request, sse):
-        for i in range(10):
-            await asyncio.sleep(1)
-            await sse.send({'counter': i})  # unnamed event
-        await sse.send('end', event='comment')  # named event
-
-To end the SSE connection, the route handler can exit, without returning
-anything, as shown in the above examples.
-
-If the client ends the SSE connection from their side, the route function is
-cancelled. The route function can catch the ``CancelledError`` exception from
-asyncio to perform cleanup tasks::
-
-    @app.route('/events')
-    @with_sse
-    async def events(request, sse):
-        try:
-            i = 0
-            while True:
-                await asyncio.sleep(1)
-                await sse.send({'counter': i})
-                i += 1
-        except asyncio.CancelledError:
-            print('Client disconnected!')
-
-.. note::
-   The SSE protocol is unidirectional, so there is no ``receive()`` method in
-   the SSE object. For bidirectional communication with the client, use the
-   WebSocket extension.
-
-Templates
-~~~~~~~~~
-
-Many web applications use HTML templates for rendering content to clients.
-Microdot includes extensions to render templates with the
-`utemplate <https://github.com/pfalcon/utemplate>`_ package on CPython and
-MicroPython, and with `Jinja <https://jinja.palletsprojects.com/>`_ only on
-CPython.
-
-Using the uTemplate Engine
-^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `utemplate.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/utemplate.py>`_
-
-   * - Required external dependencies
-     - | `utemplate <https://github.com/pfalcon/utemplate/tree/master/utemplate>`_
-
-   * - Examples
-     - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello.py>`_
-
-The :class:`Template <microdot.utemplate.Template>` class is used to load a
-template. The argument is the template filename, relative to the templates
-directory, which is *templates* by default.
-
-The ``Template`` object has a :func:`render() <microdot.utemplate.Template.render>`
-method that renders the template to a string. This method receives any
-arguments that are used by the template.
-
-Example::
-
-    from microdot.utemplate import Template
-
-    @app.get('/')
-    async def index(req):
-        return Template('index.html').render()
-
-The ``Template`` object also has a :func:`generate() <microdot.utemplate.Template.generate>`
-method, which returns a generator instead of a string. The
-:func:`render_async() <microdot.utemplate.Template.render_async>` and
-:func:`generate_async() <microdot.utemplate.Template.generate_async>` methods
-are the asynchronous versions of these two methods.
-
-The default location from where templates are loaded is the *templates*
-subdirectory. This location can be changed with the
-:func:`Template.initialize <microdot.utemplate.Template.initialize>` class
-method::
-
-    Template.initialize('my_templates')
-
-By default templates are automatically compiled the first time they are
-rendered, or when their last modified timestamp is more recent than the
-compiledo file's timestamp. This loading behavior can be changed by switching
-to a different template loader. For example, if the templates are pre-compiled,
-the timestamp check and compile steps can be removed by switching to the
-"compiled" template loader::
-
-    from utemplate import compiled
-    from microdot.utemplate import Template
-
-    Template.initialize(loader_class=compiled.Loader)
-
-Consult the `uTemplate documentation <https://github.com/pfalcon/utemplate>`_
-for additional information regarding template loaders.
-
-Using the Jinja Engine
-^^^^^^^^^^^^^^^^^^^^^^
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython only
-
-   * - Required Microdot source files
-     - | `jinja.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/jinja.py>`_
-
-   * - Required external dependencies
-     - | `Jinja2 <https://jinja.palletsprojects.com/>`_
-
-   * - Examples
-     - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello.py>`_
-
-The :class:`Template <microdot.jinja.Template>` class is used to load a
-template. The argument is the template filename, relative to the templates
-directory, which is *templates* by default.
-
-The ``Template`` object has a :func:`render() <microdot.jinja.Template.render>`
-method that renders the template to a string. This method receives any
-arguments that are used by the template.
-
-Example::
-
-    from microdot.jinja import Template
-
-    @app.get('/')
-    async def index(req):
-        return Template('index.html').render()
-
-The ``Template`` object also has a :func:`generate() <microdot.jinja.Template.generate>`
-method, which returns a generator instead of a string.
-
-The default location from where templates are loaded is the *templates*
-subdirectory. This location can be changed with the
-:func:`Template.initialize <microdot.jinja.Template.initialize>` class method::
-
-    Template.initialize('my_templates')
-
-The ``initialize()`` method also accepts ``enable_async`` argument, which
-can be set to ``True`` if asynchronous rendering of templates is desired. If
-this option is enabled, then the
-:func:`render_async() <microdot.jinja.Template.render_async>` and
-:func:`generate_async() <microdot.jinja.Template.generate_async>` methods
-must be used.
-
-.. note::
-    The Jinja extension is not compatible with MicroPython.
-
-Secure User Sessions
-~~~~~~~~~~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `session.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/session.py>`_
-       | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
-
-   * - Required external dependencies
-     - | CPython: `PyJWT <https://pyjwt.readthedocs.io/>`_
-       | MicroPython: `jwt.py <https://github.com/micropython/micropython-lib/blob/master/python-ecosys/pyjwt/jwt.py>`_,
-                      `hmac.py <https://github.com/micropython/micropython-lib/blob/master/python-stdlib/hmac/hmac.py>`_
-
-   * - Examples
-     - | `login.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/sessions/login.py>`_
-
-The session extension provides a secure way for the application to maintain
-user sessions. The session data is stored as a signed cookie in the client's
-browser, in `JSON Web Token (JWT) <https://en.wikipedia.org/wiki/JSON_Web_Token>`_
-format.
-
-To work with user sessions, the application first must configure a secret key
-that will be used to sign the session cookies. It is very important that this
-key is kept secret, as its name implies. An attacker who is in possession of
-this key can generate valid user session cookies with any contents.
-
-To initialize the session extension and configure the secret key, create a
-:class:`Session <microdot.session.Session>` object::
-
-    Session(app, secret_key='top-secret')
-
-The :func:`with_session <microdot.session.with_session>` decorator is the
-most convenient way to retrieve the session at the start of a request::
-
-    from microdot import Microdot, redirect
-    from microdot.session import Session, with_session
-
-    app = Microdot()
-    Session(app, secret_key='top-secret')
-
-    @app.route('/', methods=['GET', 'POST'])
-    @with_session
-    async def index(req, session):
-        username = session.get('username')
-        if req.method == 'POST':
-            username = req.form.get('username')
-            session['username'] = username
-            session.save()
-            return redirect('/')
-        if username is None:
-            return 'Not logged in'
-        else:
-            return 'Logged in as ' + username
-
-    @app.post('/logout')
-    @with_session
-    async def logout(req, session):
-        session.delete()
-        return redirect('/')
-
-The :func:`save() <microdot.session.SessionDict.save>` and
-:func:`delete() <microdot.session.SessionDict.delete>` methods are used to update
-and destroy the user session respectively.
-
-Authentication
-~~~~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `auth.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/auth.py>`_
-
-   * - Required external dependencies
-     - | None
-
-   * - Examples
-     - | `basic_auth.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/auth/basic_auth.py>`_
-       | `token_auth.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/auth/token_auth.py>`_
-
-The authentication extension provides helper classes for two commonly used
-authentication patterns, described below.
-
-Basic Authentication
-^^^^^^^^^^^^^^^^^^^^
-
-`Basic Authentication <https://en.wikipedia.org/wiki/Basic_access_authentication>`_
-is a method of authentication that is part of the HTTP specification. It allows
-clients to authenticate to a server using a username and a password. Web
-browsers have native support for Basic Authentication and will automatically
-prompt the user for a username and a password when a protected resource is
-accessed.
-
-To use Basic Authentication, create an instance of the :class:`BasicAuth <microdot.auth.BasicAuth>`
-class::
-
-    from microdot.auth import BasicAuth
-
-    auth = BasicAuth(app)
-
-Next, create an authentication function. The function must accept a request
-object and a username and password pair provided by the user. If the
-credentials are valid, the function must return an object that represents the
-user. If the authentication function cannot validate the user provided
-credentials it must return ``None``. Decorate the function with
-``@auth.authenticate``::
-
-    @auth.authenticate
-    async def verify_user(request, username, password):
-        user = await load_user_from_database(username)
-        if user and user.verify_password(password):
-            return user
-
-To protect a route with authentication, add the ``auth`` instance as a
-decorator::
-
-    @app.route('/')
-    @auth
-    async def index(request):
-        return f'Hello, {request.g.current_user}!'
-
-While running an authenticated request, the user object returned by the
-authenticaction function is accessible as ``request.g.current_user``.
-
-If an endpoint is intended to work with or without authentication, then it can
-be protected with the ``auth.optional`` decorator::
-
-    @app.route('/')
-    @auth.optional
-    async def index(request):
-        if request.g.current_user:
-            return f'Hello, {request.g.current_user}!'
-        else:
-            return 'Hello, anonymous user!'
-
-As shown in the example, a route can check ``request.g.current_user`` to
-determine if the user is authenticated or not.
-
-Token Authentication
-^^^^^^^^^^^^^^^^^^^^
-
-To set up token authentication, create an instance of
-:class:`TokenAuth <microdot.auth.TokenAuth>`::
-
-    from microdot.auth import TokenAuth
-
-    auth = TokenAuth()
-
-Then add a function that verifies the token and returns the user it belongs to,
-or ``None`` if the token is invalid or expired::
-
-    @auth.authenticate
-    async def verify_token(request, token):
-        return load_user_from_token(token)
-
-As with Basic authentication, the ``auth`` instance is used as a decorator to
-protect your routes, and the authenticated user is accessible from the request
-object as ``request.g.current_user``::
-
-    @app.route('/')
-    @auth
-    async def index(request):
-        return f'Hello, {request.g.current_user}!'
-
-Optional authentication can also be used with tokens::
-
-    @app.route('/')
-    @auth.optional
-    async def index(request):
-        if request.g.current_user:
-            return f'Hello, {request.g.current_user}!'
-        else:
-            return 'Hello, anonymous user!'
-
-User Logins
-~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `login.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/auth.py>`_
-       | `session.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/session.py>`_
-       | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
-   * - Required external dependencies
-     - | CPython: `PyJWT <https://pyjwt.readthedocs.io/>`_
-       | MicroPython: `jwt.py <https://github.com/micropython/micropython-lib/blob/master/python-ecosys/pyjwt/jwt.py>`_,
-                      `hmac.py <https://github.com/micropython/micropython-lib/blob/master/python-stdlib/hmac/hmac.py>`_
-   * - Examples
-     - | `login.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/login/login.py>`_
-
-The login extension provides user login functionality. The logged in state of
-the user is stored in the user session cookie, and an optional "remember me"
-cookie can also be added to keep the user logged in across browser sessions.
-
-To use this extension, create instances of the
-:class:`Session <microdot.session.Session>` and :class:`Login <microdot.login.Login>`
-class::
-
-    Session(app, secret_key='top-secret!')
-    login = Login()
-
-The ``Login`` class accept an optional argument with the URL of the login page.
-The default for this URL is */login*.
-
-The application must represent users as objects with an ``id`` attribute. A
-function decorated with ``@login.user_loader`` is used to load a user object::
-
-    @login.user_loader
-    async def get_user(user_id):
-        return database.get_user(user_id)
-
-The application must implement the login form. At the point in which the user
-credentials have been received and verified, a call to the
-:func:`login_user() <microdot.login.Login.login_user>` function must be made to
-record the user in the user session::
-
-    @app.route('/login', methods=['GET', 'POST'])
-    async def login(request):
-        # ...
-        if user.check_password(password):
-            return await login.login_user(request, user, remember=remember_me)
-        return redirect('/login')
-
-The optional ``remember`` argument is used to add a remember me cookie that
-will log the user in automatically in future sessions. A value of ``True`` will
-keep the log in active for 30 days. Alternatively, an integer number of days
-can be passed in this argument.
-
-Any routes that require the user to be logged in must be decorated with
-:func:`@login <microdot.login.Login.__call__>`::
-
-    @app.route('/')
-    @login
-    async def index(request):
-        # ...
-
-Routes that are of a sensitive nature can be decorated with
-:func:`@login.fresh <microdot.login.Login.fresh>`
-instead. This decorator requires that the user has logged in during the current
-session, and will ask the user to logged in again if the session was
-authenticated through a remember me cookie::
-
-    @app.get('/fresh')
-    @login.fresh
-    async def fresh(request):
-        # ...
-
-To log out a user, the :func:`logout_user() <microdot.auth.Login.logout_user>`
-is used::
-
-    @app.post('/logout')
-    @login
-    async def logout(request):
-        await login.logout_user(request)
-        return redirect('/')
-
-Cross-Origin Resource Sharing (CORS)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `cors.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/cors.py>`_
-
-   * - Required external dependencies
-     - | None
-
-   * - Examples
-     - | `app.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/cors/app.py>`_
-
-The CORS extension provides support for `Cross-Origin Resource Sharing
-(CORS) <https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS>`_. CORS is a
-mechanism that allows web applications running on different origins to access
-resources from each other. For example, a web application running on
-``https://example.com`` can access resources from ``https://api.example.com``.
-
-To enable CORS support, create an instance of the
-:class:`CORS <microdot.cors.CORS>` class and configure the desired options.
-Example::
-
-    from microdot import Microdot
-    from microdot.cors import CORS
-
-    app = Microdot()
-    cors = CORS(app, allowed_origins=['https://example.com'],
-                allow_credentials=True)
-
-Test Client
-~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `test_client.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/test_client.py>`_
-
-   * - Required external dependencies
-     - | None
-
-The Microdot Test Client is a utility class that can be used in tests to send
-requests into the application without having to start a web server.
-
-Example::
-
-    from microdot import Microdot
-    from microdot.test_client import TestClient
-
-    app = Microdot()
-
-    @app.route('/')
-    def index(req):
-        return 'Hello, World!'
-
-    async def test_app():
-        client = TestClient(app)
-        response = await client.get('/')
-        assert response.text == 'Hello, World!'
-
-See the documentation for the :class:`TestClient <microdot.test_client.TestClient>`
-class for more details.
-
-Production Deployments
-~~~~~~~~~~~~~~~~~~~~~~
-
-The ``Microdot`` class creates its own simple web server. This is enough for an
-application deployed with MicroPython, but when using CPython it may be useful
-to use a separate, battle-tested web server. To address this need, Microdot
-provides extensions that implement the ASGI and WSGI protocols.
-
-Using an ASGI Web Server
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython only
-
-   * - Required Microdot source files
-     - | `asgi.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/asgi.py>`_
-
-   * - Required external dependencies
-     - | An ASGI web server, such as `Uvicorn <https://www.uvicorn.org/>`_.
-
-   * - Examples
-     - | `hello_asgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_asgi.py>`_
-       | `hello_asgi.py (uTemplate) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello_asgi.py>`_
-       | `hello_asgi.py (Jinja) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello_asgi.py>`_
-       | `echo_asgi.py (WebSocket) <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_asgi.py>`_
-
-The ``asgi`` module provides an extended ``Microdot`` class that
-implements the ASGI protocol and can be used with a compliant ASGI server such
-as `Uvicorn <https://www.uvicorn.org/>`_.
-
-To use an ASGI web server, the application must import the
-:class:`Microdot <microdot.asgi.Microdot>` class from the ``asgi`` module::
-
-    from microdot.asgi import Microdot
-
-    app = Microdot()
-
-    @app.route('/')
-    async def index(req):
-        return 'Hello, World!'
-
-The ``app`` application instance created from this class can be used as the
-ASGI callable with any complaint ASGI web server. If the above example
-application was stored in a file called *test.py*, then the following command
-runs the web application using the Uvicorn web server::
-
-    uvicorn test:app
-
-When using the ASGI support, the ``scope`` dictionary provided by the web
-server is available to request handlers as ``request.asgi_scope``.
-
-Using a WSGI Web Server
-^^^^^^^^^^^^^^^^^^^^^^^
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython only
-
-   * - Required Microdot source files
-     - | `wsgi.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/wsgi.py>`_
-
-   * - Required external dependencies
-     - | A WSGI web server, such as `Gunicorn <https://gunicorn.org/>`_.
-
-   * - Examples
-     - | `hello_wsgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_wsgi.py>`_
-       | `hello_wsgi.py (uTemplate) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello_wsgi.py>`_
-       | `hello_wsgi.py (Jinja) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello_wsgi.py>`_
-       | `echo_wsgi.py (WebSocket) <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_wsgi.py>`_
-
-
-The ``wsgi`` module provides an extended ``Microdot`` class that implements the
-WSGI protocol and can be used with a compliant WSGI web server such as 
-`Gunicorn <https://gunicorn.org/>`_ or
-`uWSGI <https://uwsgi-docs.readthedocs.io/en/latest/>`_.
-
-To use a WSGI web server, the application must import the
-:class:`Microdot <microdot.wsgi.Microdot>` class from the ``wsgi`` module::
-
-    from microdot.wsgi import Microdot
-
-    app = Microdot()
-
-    @app.route('/')
-    def index(req):
-        return 'Hello, World!'
-
-The ``app`` application instance created from this class can be used as a WSGI
-callbable with any complaint WSGI web server. If the above application
-was stored in a file called *test.py*, then the following command runs the
-web application using the Gunicorn web server::
-
-    gunicorn test:app
-
-When using the WSGI support, the ``environ`` dictionary provided by the web
-server is available to request handlers as ``request.environ``.
-
-.. note::
-    In spite of WSGI being a synchronous protocol, the Microdot application
-    internally runs under an asyncio event loop. For that reason, the
-    recommendation to prefer ``async def`` handlers over ``def`` still applies
-    under WSGI. Consult the :ref:`Concurrency` section for a discussion of how
-    the two types of functions are handled by Microdot.

docs/extensions/auth.rst

@@ -0,0 +1,112 @@
+Authentication
+~~~~~~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     - | `auth.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/auth.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `basic_auth.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/auth/basic_auth.py>`_
+       | `token_auth.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/auth/token_auth.py>`_
+
+The authentication extension provides helper classes for two commonly used
+authentication patterns, described below.
+
+Basic Authentication
+^^^^^^^^^^^^^^^^^^^^
+
+`Basic Authentication <https://en.wikipedia.org/wiki/Basic_access_authentication>`_
+is a method of authentication that is part of the HTTP specification. It allows
+clients to authenticate to a server using a username and a password. Web
+browsers have native support for Basic Authentication and will automatically
+prompt the user for a username and a password when a protected resource is
+accessed.
+
+To use Basic Authentication, create an instance of the :class:`BasicAuth <microdot.auth.BasicAuth>`
+class::
+
+    from microdot.auth import BasicAuth
+
+    auth = BasicAuth(app)
+
+Next, create an authentication function. The function must accept a request
+object and a username and password pair provided by the user. If the
+credentials are valid, the function must return an object that represents the
+user. If the authentication function cannot validate the user provided
+credentials it must return ``None``. Decorate the function with
+``@auth.authenticate``::
+
+    @auth.authenticate
+    async def verify_user(request, username, password):
+        user = await load_user_from_database(username)
+        if user and user.verify_password(password):
+            return user
+
+To protect a route with authentication, add the ``auth`` instance as a
+decorator::
+
+    @app.route('/')
+    @auth
+    async def index(request):
+        return f'Hello, {request.g.current_user}!'
+
+While running an authenticated request, the user object returned by the
+authenticaction function is accessible as ``request.g.current_user``.
+
+If an endpoint is intended to work with or without authentication, then it can
+be protected with the ``auth.optional`` decorator::
+
+    @app.route('/')
+    @auth.optional
+    async def index(request):
+        if request.g.current_user:
+            return f'Hello, {request.g.current_user}!'
+        else:
+            return 'Hello, anonymous user!'
+
+As shown in the example, a route can check ``request.g.current_user`` to
+determine if the user is authenticated or not.
+
+Token Authentication
+^^^^^^^^^^^^^^^^^^^^
+
+To set up token authentication, create an instance of
+:class:`TokenAuth <microdot.auth.TokenAuth>`::
+
+    from microdot.auth import TokenAuth
+
+    auth = TokenAuth()
+
+Then add a function that verifies the token and returns the user it belongs to,
+or ``None`` if the token is invalid or expired::
+
+    @auth.authenticate
+    async def verify_token(request, token):
+        return load_user_from_token(token)
+
+As with Basic authentication, the ``auth`` instance is used as a decorator to
+protect your routes, and the authenticated user is accessible from the request
+object as ``request.g.current_user``::
+
+    @app.route('/')
+    @auth
+    async def index(request):
+        return f'Hello, {request.g.current_user}!'
+
+Optional authentication can also be used with tokens::
+
+    @app.route('/')
+    @auth.optional
+    async def index(request):
+        if request.g.current_user:
+            return f'Hello, {request.g.current_user}!'
+        else:
+            return 'Hello, anonymous user!'

docs/extensions/cors.rst

@@ -0,0 +1,34 @@
+Cross-Origin Resource Sharing (CORS)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     - | `cors.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/cors.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `app.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/cors/app.py>`_
+
+The CORS extension provides support for `Cross-Origin Resource Sharing
+(CORS) <https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS>`_. CORS is a
+mechanism that allows web applications running on different origins to access
+resources from each other. For example, a web application running on
+``https://example.com`` can access resources from ``https://api.example.com``.
+
+To enable CORS support, create an instance of the
+:class:`CORS <microdot.cors.CORS>` class and configure the desired options.
+Example::
+
+    from microdot import Microdot
+    from microdot.cors import CORS
+
+    app = Microdot()
+    cors = CORS(app, allowed_origins=['https://example.com'],
+                allow_credentials=True)

docs/extensions/csrf.rst

@@ -0,0 +1,94 @@
+Cross-Site Request Forgery (CSRF) Protection
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     - | `csrf.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/csrf.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `app.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/csrf/app.py>`_
+
+The CSRF extension provides protection against `Cross-Site Request Forgery
+(CSRF) <https://owasp.org/www-community/attacks/csrf>`_ attacks. This
+protection defends against attackers attempting to submit forms or other
+state-changing requests from their own site on behalf of unsuspecting victims,
+while taking advantage of the victims previously established sessions or
+cookies to impersonate them.
+
+This extension checks the ``Sec-Fetch-Site`` header sent by all modern web
+browsers to achieve this protection. As a fallback mechanism for older browsers
+that do not support this header, this extension can be linked to the CORS
+extension to validate the ``Origin`` header. If you are interested in the
+details of this protection mechanism, it is described in the
+`OWASP CSRF Prevention Cheat Sheet <https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html#fetch-metadata-headers>`_
+page.
+
+.. note::
+   As of December 2025, OWASP considers the use of Fetch Metadata Headers for
+   CSRF protection a
+   `defense in depth <https://en.wikipedia.org/wiki/Defence_in_depth>`_
+   technique that is insufficient on its own.
+
+   There is an interesting
+   `discussion <https://github.com/OWASP/CheatSheetSeries/issues/1803>`_ on
+   this topic in the OWASP GitHub repository where it appears to be agreement
+   that this technique provides complete protection for the vast majority of
+   use cases. If you are unsure if this method works for your use case, please
+   read this discussion to have more context and make the right decision. 
+
+To enable CSRF protection, create an instance of the
+:class:`CSRF <microdot.csrf.CSRF>` class and configure the desired options.
+Example::
+
+    from microdot import Microdot
+    from microdot.cors import CORS
+    from microdot.csrf import CSRF
+
+    app = Microdot()
+    cors = CORS(app, allowed_origins=['https://example.com'])
+    csrf = CSRF(app, cors)
+
+This will protect all routes that use a state-changing method (``POST``,
+``PUT``, ``PATCH`` or ``DELETE``) and will return a 403 status code response to
+any requests that fail the CSRF check.
+
+If there are routes that need to be exempted from the CSRF check, they can be
+decorated with the :meth:`csrf.exempt <microdot.csrf.CSRF.exempt>` decorator::
+
+    @app.post('/webhook')
+    @csrf.exempt
+    async def webhook(request):
+        # ...
+
+For some applications it may be more convenient to have CSRF checks turned off
+by default, and only apply them to explicitly selected routes. In this case,
+pass ``protect_all=False`` when you construct the ``CSRF`` instance and use the
+:meth:`csrf.protect <microdot.csrf.CSRF.protect>` decorator::
+
+    csrf = CSRF(app, cors, protect_all=False)
+
+    @app.post('/submit-form')
+    @csrf.protect
+    async def submit_form(request):
+        # ...
+
+By default, requests coming from different subdomains are considered to be
+cross-site, and as such they will not pass the CSRF check. If you'd like
+subdomain requests to be considered safe, then set the
+``allow_subdomains=True`` option when you create the ``CSRF`` class.
+
+.. note::
+   This extension is designed to block requests issued by web browsers when
+   they are found to be unsafe or unauthorized by the application owner. The
+   method used to determine if a request should be allowed or not is based on
+   the value of headers that are only sent by web browsers. Clients other than
+   web browsers are not affected by this extension and can send requests
+   freely.

docs/extensions/index.rst

@@ -0,0 +1,21 @@
+Core Extensions
+---------------
+
+Microdot is a highly extensible web application framework. The extensions
+described in this section are maintained as part of the Microdot project in
+the same source code repository.
+
+.. toctree::
+   :maxdepth: 1
+
+   multipart
+   websocket
+   sse
+   templates
+   sessions
+   auth
+   login
+   cors
+   csrf
+   test_client
+   production

docs/extensions/login.rst

@@ -0,0 +1,85 @@
+User Logins
+~~~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     - | `login.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/auth.py>`_
+       | `session.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/session.py>`_
+       | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
+   * - Required external dependencies
+     - | CPython: `PyJWT <https://pyjwt.readthedocs.io/>`_
+       | MicroPython: `jwt.py <https://github.com/micropython/micropython-lib/blob/master/python-ecosys/pyjwt/jwt.py>`_,
+                      `hmac.py <https://github.com/micropython/micropython-lib/blob/master/python-stdlib/hmac/hmac.py>`_
+   * - Examples
+     - | `login.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/login/login.py>`_
+
+The login extension provides user login functionality. The logged in state of
+the user is stored in the user session cookie, and an optional "remember me"
+cookie can also be added to keep the user logged in across browser sessions.
+
+To use this extension, create instances of the
+:class:`Session <microdot.session.Session>` and :class:`Login <microdot.login.Login>`
+class::
+
+    Session(app, secret_key='top-secret!')
+    login = Login()
+
+The ``Login`` class accept an optional argument with the URL of the login page.
+The default for this URL is */login*.
+
+The application must represent users as objects with an ``id`` attribute. A
+function decorated with ``@login.user_loader`` is used to load a user object::
+
+    @login.user_loader
+    async def get_user(user_id):
+        return database.get_user(user_id)
+
+The application must implement the login form. At the point in which the user
+credentials have been received and verified, a call to the
+:func:`login_user() <microdot.login.Login.login_user>` function must be made to
+record the user in the user session::
+
+    @app.route('/login', methods=['GET', 'POST'])
+    async def login(request):
+        # ...
+        if user.check_password(password):
+            return await login.login_user(request, user, remember=remember_me)
+        return redirect('/login')
+
+The optional ``remember`` argument is used to add a remember me cookie that
+will log the user in automatically in future sessions. A value of ``True`` will
+keep the log in active for 30 days. Alternatively, an integer number of days
+can be passed in this argument.
+
+Any routes that require the user to be logged in must be decorated with
+:func:`@login <microdot.login.Login.__call__>`::
+
+    @app.route('/')
+    @login
+    async def index(request):
+        # ...
+
+Routes that are of a sensitive nature can be decorated with
+:func:`@login.fresh <microdot.login.Login.fresh>`
+instead. This decorator requires that the user has logged in during the current
+session, and will ask the user to logged in again if the session was
+authenticated through a remember me cookie::
+
+    @app.get('/fresh')
+    @login.fresh
+    async def fresh(request):
+        # ...
+
+To log out a user, the :func:`logout_user() <microdot.auth.Login.logout_user>`
+is used::
+
+    @app.post('/logout')
+    @login
+    async def logout(request):
+        await login.logout_user(request)
+        return redirect('/')

docs/extensions/multipart.rst

@@ -0,0 +1,73 @@
+Multipart Forms
+~~~~~~~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     -  | `multipart.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/multipart.py>`_
+        | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `formdata.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/uploads/formdata.py>`_
+
+The multipart extension handles multipart forms, including those that have file
+uploads.
+
+The :func:`with_form_data <microdot.multipart.with_form_data>` decorator
+provides the simplest way to work with these forms. With this decorator added
+to the route, whenever the client sends a multipart request the
+:attr:`request.form <microdot.Request.form>` and
+:attr:`request.files <microdot.Request.files>` properties are populated with
+the submitted data. For form fields the field values are always strings. For
+files, they are instances of the
+:class:`FileUpload <microdot.multipart.FileUpload>` class.
+
+Example::
+
+    from microdot.multipart import with_form_data
+
+    @app.post('/upload')
+    @with_form_data
+    async def upload(request):
+        print('form fields:', request.form)
+        print('files:', request.files)
+
+One disadvantage of the ``@with_form_data`` decorator is that it has to copy
+any uploaded files to memory or temporary disk files, depending on their size.
+The :attr:`FileUpload.max_memory_size <microdot.multipart.FileUpload.max_memory_size>`
+attribute can be used to control the cutoff size above which a file upload
+is transferred to a temporary file.
+
+A more performant alternative to the ``@with_form_data`` decorator is the
+:class:`FormDataIter <microdot.multipart.FormDataIter>` class, which iterates
+over the form fields sequentially, giving the application the option to parse
+the form fields on the fly and decide what to copy and what to discard. When
+using ``FormDataIter`` the ``request.form`` and ``request.files`` attributes
+are not used.
+
+Example::
+
+
+    from microdot.multipart import FormDataIter
+
+    @app.post('/upload')
+    async def upload(request):
+        async for name, value in FormDataIter(request):
+            print(name, value)
+
+For fields that contain an uploaded file, the ``value`` returned by the
+iterator is the same ``FileUpload`` instance. The application can choose to
+save the file with the :meth:`save() <microdot.multipart.FileUpload.save>`
+method, or read it with the :meth:`read() <microdot.multipart.FileUpload.read>`
+method, optionally passing a size to read it in chunks. The
+:meth:`copy() <microdot.multipart.FileUpload.copy>` method is also available to
+apply the copying logic used by the ``@with_form_data`` decorator, which is
+inefficient but allows the file to be set aside to be processed later, after
+the remaining form fields.

docs/extensions/production.rst

@@ -0,0 +1,120 @@
+Production Deployments
+~~~~~~~~~~~~~~~~~~~~~~
+
+The ``Microdot`` class creates its own simple web server. This is enough for an
+application deployed with MicroPython, but when using CPython it may be useful
+to use a separate, battle-tested web server. To address this need, Microdot
+provides extensions that implement the ASGI and WSGI protocols.
+
+Using an ASGI Web Server
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython only
+
+   * - Required Microdot source files
+     - | `asgi.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/asgi.py>`_
+
+   * - Required external dependencies
+     - | An ASGI web server, such as `Uvicorn <https://www.uvicorn.org/>`_.
+
+   * - Examples
+     - | `hello_asgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_asgi.py>`_
+       | `hello_asgi.py (uTemplate) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello_asgi.py>`_
+       | `hello_asgi.py (Jinja) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello_asgi.py>`_
+       | `echo_asgi.py (WebSocket) <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_asgi.py>`_
+
+The ``asgi`` module provides an extended ``Microdot`` class that
+implements the ASGI protocol and can be used with a compliant ASGI server such
+as `Uvicorn <https://www.uvicorn.org/>`_.
+
+To use an ASGI web server, the application must import the
+:class:`Microdot <microdot.asgi.Microdot>` class from the ``asgi`` module::
+
+    from microdot.asgi import Microdot
+
+    app = Microdot()
+
+    @app.route('/')
+    async def index(req):
+        return 'Hello, World!'
+
+The ``app`` application instance created from this class can be used as the
+ASGI callable with any complaint ASGI web server. If the above example
+application was stored in a file called *test.py*, then the following command
+runs the web application using the Uvicorn web server::
+
+    uvicorn test:app
+
+When using the ASGI support, the ``scope`` dictionary provided by the web
+server is available to request handlers as ``request.asgi_scope``.
+
+The application instance can be initialized with ``lifespan_startup`` and
+``lifespan_shutdown`` arguments, which are invoked when the web server sends
+the ASGI lifespan signals with the ASGI scope as only argument::
+
+    async def startup(scope):
+        pass
+
+    async def shutdown(scope):
+        pass
+
+    app = Microdot(lifespan_startup=startup, lifespan_shutdown=shutdown)
+
+Using a WSGI Web Server
+^^^^^^^^^^^^^^^^^^^^^^^
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython only
+
+   * - Required Microdot source files
+     - | `wsgi.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/wsgi.py>`_
+
+   * - Required external dependencies
+     - | A WSGI web server, such as `Gunicorn <https://gunicorn.org/>`_.
+
+   * - Examples
+     - | `hello_wsgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_wsgi.py>`_
+       | `hello_wsgi.py (uTemplate) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello_wsgi.py>`_
+       | `hello_wsgi.py (Jinja) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello_wsgi.py>`_
+       | `echo_wsgi.py (WebSocket) <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_wsgi.py>`_
+
+
+The ``wsgi`` module provides an extended ``Microdot`` class that implements the
+WSGI protocol and can be used with a compliant WSGI web server such as 
+`Gunicorn <https://gunicorn.org/>`_ or
+`uWSGI <https://uwsgi-docs.readthedocs.io/en/latest/>`_.
+
+To use a WSGI web server, the application must import the
+:class:`Microdot <microdot.wsgi.Microdot>` class from the ``wsgi`` module::
+
+    from microdot.wsgi import Microdot
+
+    app = Microdot()
+
+    @app.route('/')
+    def index(req):
+        return 'Hello, World!'
+
+The ``app`` application instance created from this class can be used as a WSGI
+callbable with any complaint WSGI web server. If the above application
+was stored in a file called *test.py*, then the following command runs the
+web application using the Gunicorn web server::
+
+    gunicorn test:app
+
+When using the WSGI support, the ``environ`` dictionary provided by the web
+server is available to request handlers as ``request.environ``.
+
+.. note::
+    In spite of WSGI being a synchronous protocol, the Microdot application
+    internally runs under an asyncio event loop. For that reason, the
+    recommendation to prefer ``async def`` handlers over ``def`` still applies
+    under WSGI. Consult the :ref:`Concurrency` section for a discussion of how
+    the two types of functions are handled by Microdot.

docs/extensions/sessions.rst

@@ -0,0 +1,68 @@
+Secure User Sessions
+~~~~~~~~~~~~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     - | `session.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/session.py>`_
+       | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
+
+   * - Required external dependencies
+     - | CPython: `PyJWT <https://pyjwt.readthedocs.io/>`_
+       | MicroPython: `jwt.py <https://github.com/micropython/micropython-lib/blob/master/python-ecosys/pyjwt/jwt.py>`_,
+                      `hmac.py <https://github.com/micropython/micropython-lib/blob/master/python-stdlib/hmac/hmac.py>`_
+
+   * - Examples
+     - | `login.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/sessions/login.py>`_
+
+The session extension provides a secure way for the application to maintain
+user sessions. The session data is stored as a signed cookie in the client's
+browser, in `JSON Web Token (JWT) <https://en.wikipedia.org/wiki/JSON_Web_Token>`_
+format.
+
+To work with user sessions, the application first must configure a secret key
+that will be used to sign the session cookies. It is very important that this
+key is kept secret, as its name implies. An attacker who is in possession of
+this key can generate valid user session cookies with any contents.
+
+To initialize the session extension and configure the secret key, create a
+:class:`Session <microdot.session.Session>` object::
+
+    Session(app, secret_key='top-secret')
+
+The :func:`with_session <microdot.session.with_session>` decorator is the
+most convenient way to retrieve the session at the start of a request::
+
+    from microdot import Microdot, redirect
+    from microdot.session import Session, with_session
+
+    app = Microdot()
+    Session(app, secret_key='top-secret')
+
+    @app.route('/', methods=['GET', 'POST'])
+    @with_session
+    async def index(req, session):
+        username = session.get('username')
+        if req.method == 'POST':
+            username = req.form.get('username')
+            session['username'] = username
+            session.save()
+            return redirect('/')
+        if username is None:
+            return 'Not logged in'
+        else:
+            return 'Logged in as ' + username
+
+    @app.post('/logout')
+    @with_session
+    async def logout(req, session):
+        session.delete()
+        return redirect('/')
+
+The :func:`save() <microdot.session.SessionDict.save>` and
+:func:`delete() <microdot.session.SessionDict.delete>` methods are used to update
+and destroy the user session respectively.

docs/extensions/sse.rst

@@ -0,0 +1,60 @@
+Server-Sent Events
+~~~~~~~~~~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     -  | `sse.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/sse.py>`_
+        | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `counter.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/sse/counter.py>`_
+
+The Server-Sent Events (SSE) extension simplifies the creation of a streaming
+endpoint that follows the SSE web standard. The :func:`with_sse <microdot.sse.with_sse>`
+decorator is used to mark a route as an SSE handler. Decorated routes receive
+an SSE object as second argument. The SSE object provides a ``send()``
+asynchronous method to send an event to the client.
+
+Example::
+
+    from microdot.sse import with_sse
+
+    @app.route('/events')
+    @with_sse
+    async def events(request, sse):
+        for i in range(10):
+            await asyncio.sleep(1)
+            await sse.send({'counter': i})  # unnamed event
+        await sse.send('end', event='comment')  # named event
+
+To end the SSE connection, the route handler can exit, without returning
+anything, as shown in the above examples.
+
+If the client ends the SSE connection from their side, the route function is
+cancelled. The route function can catch the ``CancelledError`` exception from
+asyncio to perform cleanup tasks::
+
+    @app.route('/events')
+    @with_sse
+    async def events(request, sse):
+        try:
+            i = 0
+            while True:
+                await asyncio.sleep(1)
+                await sse.send({'counter': i})
+                i += 1
+        except asyncio.CancelledError:
+            print('Client disconnected!')
+
+.. note::
+   The SSE protocol is unidirectional, so there is no ``receive()`` method in
+   the SSE object. For bidirectional communication with the client, use the
+   WebSocket extension.

docs/extensions/templates.rst

@@ -0,0 +1,123 @@
+Templates
+~~~~~~~~~
+
+Many web applications use HTML templates for rendering content to clients.
+Microdot includes extensions to render templates with the
+`utemplate <https://github.com/pfalcon/utemplate>`_ package on CPython and
+MicroPython, and with `Jinja <https://jinja.palletsprojects.com/>`_ only on
+CPython.
+
+Using the uTemplate Engine
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     - | `utemplate.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/utemplate.py>`_
+
+   * - Required external dependencies
+     - | `utemplate <https://github.com/pfalcon/utemplate/tree/master/utemplate>`_
+
+   * - Examples
+     - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello.py>`_
+
+The :class:`Template <microdot.utemplate.Template>` class is used to load a
+template. The argument is the template filename, relative to the templates
+directory, which is *templates* by default.
+
+The ``Template`` object has a :func:`render() <microdot.utemplate.Template.render>`
+method that renders the template to a string. This method receives any
+arguments that are used by the template.
+
+Example::
+
+    from microdot.utemplate import Template
+
+    @app.get('/')
+    async def index(req):
+        return Template('index.html').render()
+
+The ``Template`` object also has a :func:`generate() <microdot.utemplate.Template.generate>`
+method, which returns a generator instead of a string. The
+:func:`render_async() <microdot.utemplate.Template.render_async>` and
+:func:`generate_async() <microdot.utemplate.Template.generate_async>` methods
+are the asynchronous versions of these two methods.
+
+The default location from where templates are loaded is the *templates*
+subdirectory. This location can be changed with the
+:func:`Template.initialize <microdot.utemplate.Template.initialize>` class
+method::
+
+    Template.initialize('my_templates')
+
+By default templates are automatically compiled the first time they are
+rendered, or when their last modified timestamp is more recent than the
+compiledo file's timestamp. This loading behavior can be changed by switching
+to a different template loader. For example, if the templates are pre-compiled,
+the timestamp check and compile steps can be removed by switching to the
+"compiled" template loader::
+
+    from utemplate import compiled
+    from microdot.utemplate import Template
+
+    Template.initialize(loader_class=compiled.Loader)
+
+Consult the `uTemplate documentation <https://github.com/pfalcon/utemplate>`_
+for additional information regarding template loaders.
+
+Using the Jinja Engine
+^^^^^^^^^^^^^^^^^^^^^^
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython only
+
+   * - Required Microdot source files
+     - | `jinja.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/jinja.py>`_
+
+   * - Required external dependencies
+     - | `Jinja2 <https://jinja.palletsprojects.com/>`_
+
+   * - Examples
+     - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello.py>`_
+
+The :class:`Template <microdot.jinja.Template>` class is used to load a
+template. The argument is the template filename, relative to the templates
+directory, which is *templates* by default.
+
+The ``Template`` object has a :func:`render() <microdot.jinja.Template.render>`
+method that renders the template to a string. This method receives any
+arguments that are used by the template.
+
+Example::
+
+    from microdot.jinja import Template
+
+    @app.get('/')
+    async def index(req):
+        return Template('index.html').render()
+
+The ``Template`` object also has a :func:`generate() <microdot.jinja.Template.generate>`
+method, which returns a generator instead of a string.
+
+The default location from where templates are loaded is the *templates*
+subdirectory. This location can be changed with the
+:func:`Template.initialize <microdot.jinja.Template.initialize>` class method::
+
+    Template.initialize('my_templates')
+
+The ``initialize()`` method also accepts ``enable_async`` argument, which
+can be set to ``True`` if asynchronous rendering of templates is desired. If
+this option is enabled, then the
+:func:`render_async() <microdot.jinja.Template.render_async>` and
+:func:`generate_async() <microdot.jinja.Template.generate_async>` methods
+must be used.
+
+.. note::
+    The Jinja extension is not compatible with MicroPython.

docs/extensions/test_client.rst

@@ -0,0 +1,36 @@
+Test Client
+~~~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     - | `test_client.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/test_client.py>`_
+
+   * - Required external dependencies
+     - | None
+
+The Microdot Test Client is a utility class that can be used in tests to send
+requests into the application without having to start a web server.
+
+Example::
+
+    from microdot import Microdot
+    from microdot.test_client import TestClient
+
+    app = Microdot()
+
+    @app.route('/')
+    def index(req):
+        return 'Hello, World!'
+
+    async def test_app():
+        client = TestClient(app)
+        response = await client.get('/')
+        assert response.text == 'Hello, World!'
+
+See the documentation for the :class:`TestClient <microdot.test_client.TestClient>`
+class for more details.

docs/extensions/websocket.rst

@@ -0,0 +1,63 @@
+WebSocket
+~~~~~~~~~
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython & MicroPython
+
+   * - Required Microdot source files
+     -  | `websocket.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/websocket.py>`_
+        | `helpers.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/helpers.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `echo.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo.py>`_
+
+The WebSocket extension gives the application the ability to handle WebSocket
+requests. The :func:`with_websocket <microdot.websocket.with_websocket>`
+decorator is used to mark a route handler as a WebSocket handler. Decorated
+routes receive a WebSocket object as a second argument. The WebSocket object
+provides ``send()`` and ``receive()`` asynchronous methods to send and receive
+messages respectively.
+
+Example::
+
+    from microdot.websocket import with_websocket
+
+    @app.route('/echo')
+    @with_websocket
+    async def echo(request, ws):
+        while True:
+            message = await ws.receive()
+            await ws.send(message)
+
+To end the WebSocket connection, the route handler can exit, without returning
+anything::
+
+    @app.route('/echo')
+    @with_websocket
+    async def echo(request, ws):
+        while True:
+            message = await ws.receive()
+            if message == 'exit':
+                break
+            await ws.send(message)
+        await ws.send('goodbye')
+
+If the client ends the WebSocket connection from their side, the route function
+is cancelled. The route function can catch the ``CancelledError`` exception
+from asyncio to perform cleanup tasks::
+
+    @app.route('/echo')
+    @with_websocket
+    async def echo(request, ws):
+        try:
+            while True:
+                message = await ws.receive()
+                await ws.send(message)
+        except asyncio.CancelledError:
+            print('Client disconnected!')

docs/implementation/index.rst

@@ -0,0 +1,11 @@
+Implementation notes
+--------------------
+
+This section covers some implementation aspects of Microdot.
+
+.. toctree::
+   :maxdepth: 1
+
+   migrating
+   freezing
+

docs/index.rst

@@ -14,13 +14,14 @@ systems with limited resources such as microcontrollers. Both standard Python
 (CPython) and `MicroPython <https://micropython.org>`_ are supported.
 
 .. toctree::
-   :maxdepth: 3
+   :maxdepth: 2 
 
    intro
-   extensions
-   migrating
-   freezing
-   api
+   users-guide/index
+   extensions/index
+   implementation/index
+   api/index
+   contributing
 
 * :ref:`genindex`
 * :ref:`search`

docs/intro.rst

@@ -1,13 +1,14 @@
 Installation
 ------------
 
-The installation method is different depending on the version of Python.
+The installation method is different depending on which flavor of Python you 
+are using.
 
 CPython Installation
 ~~~~~~~~~~~~~~~~~~~~
 
 For use with standard Python (CPython) projects, Microdot and all of its core
-extensions are installed with ``pip``::
+extensions are installed with ``pip`` or any of its alternatives::
 
     pip install microdot
 
@@ -17,970 +18,27 @@ MicroPython Installation
 For MicroPython, the recommended approach is to manually copy the necessary
 source files from the
 `GitHub repository <https://github.com/miguelgrinberg/microdot/tree/main/src>`_
-into your device, ideally after
-`compiling <https://docs.micropython.org/en/latest/reference/mpyfiles.html>`_
-them to *.mpy* files. These source files can also be
-`frozen <https://docs.micropython.org/en/latest/develop/optimizations.html?highlight=frozen#frozen-bytecode>`_
-and incorporated into a custom MicroPython firmware.
+into your device.
 
 Use the following guidelines to know what files to copy:
 
 * For a minimal setup with only the base web server functionality, copy
   `microdot.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/microdot.py>`_
-  into your project.
-* For a configuration that includes one or more optional extensions, create a
-  *microdot* directory in your device and copy the following files:
+  to your device.
+* For a configuration that includes one or more of the optional extensions,
+  create a *microdot* directory in your device and copy the following files:
 
   * `__init__.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/__init__.py>`_
   * `microdot.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/microdot.py>`_
   * any needed `extensions <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot>`_.
 
+Some of the low end devices are perfectly capable of running Microdot once
+compiled, but do not have enough RAM for the compiler. For these cases you can
+`pre-compile <https://docs.micropython.org/en/latest/reference/mpyfiles.html>`_
+the files to *.mpy* files for the version of MicroPython that you use in your
+device.
 
-Getting Started
----------------
+If space in your device is extremely tight, you may also consider
+`freezing <https://docs.micropython.org/en/latest/develop/optimizations.html?highlight=frozen#frozen-bytecode>`_
+the Microdot files and incorporating them into a custom MicroPython firmware.
 
-This section describes the main features of Microdot in an informal manner.
-
-For detailed reference information, consult the :ref:`API Reference`.
-
-If you are familiar with releases of Microdot before 2.x, review the
-:ref:`Migration Guide <Migrating to Microdot 2.x from Older Releases>`.
-
-A Simple Microdot Web Server
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-The following is an example of a simple web server::
-
-    from microdot import Microdot
-
-    app = Microdot()
-
-    @app.route('/')
-    async def index(request):
-        return 'Hello, world!'
-
-    app.run()
-
-The script imports the :class:`Microdot <microdot.Microdot>` class and creates
-an application instance from it.
-
-The application instance provides a :func:`route() <microdot.Microdot.route>`
-decorator, which is used to define one or more routes, as needed by the
-application.
-
-The ``route()`` decorator takes the path portion of the URL as an
-argument, and maps it to the decorated function, so that the function is called
-when the client requests the URL.
-
-When the function is called, it is passed a :class:`Request <microdot.Request>`
-object as an argument, which provides access to the information passed by the
-client. The value returned by the function is sent back to the client as the
-response.
-
-Microdot is an asynchronous framework that uses the ``asyncio`` package. Route
-handler functions can be defined as ``async def`` or ``def`` functions, but
-``async def`` functions are recommended for performance.
-
-The :func:`run() <microdot.Microdot.run>` method starts the application's web
-server on port 5000 by default, and creates its own asynchronous loop. This
-method blocks while it waits for connections from clients.
-
-For some applications it may be necessary to run the web server alongside other
-asynchronous tasks, on an already running loop. In that case, instead of
-``app.run()`` the web server can be started by invoking the
-:func:`start_server() <microdot.Microdot.start_server>` coroutine as shown in
-the following example::
-
-    import asyncio
-    from microdot import Microdot
-
-    app = Microdot()
-
-    @app.route('/')
-    async def index(request):
-        return 'Hello, world!'
-
-    async def main():
-        # start the server in a background task
-        server = asyncio.create_task(app.start_server())
-
-        # ... do other asynchronous work here ...
-
-        # cleanup before ending the application
-        await server
-
-    asyncio.run(main())
-
-Running with CPython
-^^^^^^^^^^^^^^^^^^^^
-
-.. list-table::
-   :align: left
-
-   * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/microdot.py>`_
-
-   * - Required external dependencies
-     - | None
-
-   * - Examples
-     - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello.py>`_
-
-When using CPython, you can start the web server by running the script that
-has the ``app.run()`` call at the bottom::
-
-    python main.py
-
-After starting the script, open a web browser and navigate to
-*http://localhost:5000/* to access the application at the default address for
-the Microdot web server. From other computers in the same network, use the IP
-address or hostname of the computer running the script instead of
-``localhost``.
-
-Running with MicroPython
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-.. list-table::
-   :align: left
-
-   * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/microdot.py>`_
-
-   * - Required external dependencies
-     - | None
-
-   * - Examples
-     - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello.py>`_
-       | `gpio.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/gpio/gpio.py>`_
-
-When using MicroPython, you can upload a *main.py* file containing the web
-server code to your device, along with the required Microdot files, as defined
-in the :ref:`MicroPython Installation` section.
-
-MicroPython will automatically run *main.py* when the device is powered on, so
-the web server will automatically start. The application can be accessed on
-port 5000 at the device's IP address. As indicated above, the port can be
-changed by passing the ``port`` argument to the ``run()`` method.
-
-.. note::
-   Microdot does not configure the network interface of the device in which it
-   is running. If your device requires a network connection to be made in
-   advance, for example to a Wi-Fi access point, this must be configured before
-   the ``run()`` method is invoked.
-
-Web Server Configuration
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-The :func:`run() <microdot.Microdot.run>` and
-:func:`start_server() <microdot.Microdot.start_server>` methods support a few
-arguments to configure the web server.
-
-- ``port``: The port number to listen on. Pass the desired port number in this
-  argument to use a port different than the default of 5000. For example::
-
-    app.run(port=6000)
-
-- ``host``: The IP address of the network interface to listen on. By default
-  the server listens on all available interfaces. To listen only on the local
-  loopback interface, pass ``'127.0.0.1'`` as value for this argument.
-- ``debug``: when set to ``True``, the server ouputs logging information to the
-  console. The default is ``False``.
-- ``ssl``: an ``SSLContext`` instance that configures the server to use TLS
-  encryption, or ``None`` to disable TLS use. The default is ``None``. The
-  following example demonstrates how to configure the server with an SSL
-  certificate stored in *cert.pem* and *key.pem* files::
-
-    import ssl
-
-    # ...
-
-    sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
-    sslctx.load_cert_chain('cert.pem', 'key.pem')
-    app.run(port=4443, debug=True, ssl=sslctx)
-
-.. note::
-   When using CPython, the certificate and key files must be given in PEM
-   format. When using MicroPython, these files must be given in DER format.
-
-Defining Routes
-~~~~~~~~~~~~~~~
-
-The :func:`route() <microdot.Microdot.route>` decorator is used to associate an
-application URL with the function that handles it. The only required argument
-to the decorator is the path portion of the URL.
-
-The following example creates a route for the root URL of the application::
-
-    @app.route('/')
-    async def index(request):
-        return 'Hello, world!'
-
-When a client requests the root URL (for example, *http://localhost:5000/*),
-Microdot will call the ``index()`` function, passing it a
-:class:`Request <microdot.Request>` object. The return value of the function
-is the response that is sent to the client.
-
-Below is another example, this one with a route for a URL with two components
-in its path::
-
-    @app.route('/users/active')
-    async def active_users(request):
-        return 'Active users: Susan, Joe, and Bob'
-
-The complete URL that maps to this route is
-*http://localhost:5000/users/active*.
-
-An application can include multiple routes. Microdot uses the path portion of
-the URL to determine the correct route function to call for each incoming
-request.
-
-Choosing the HTTP Method
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-All the example routes shown above are associated with ``GET`` requests, which
-are the default. Applications often need to define routes for other HTTP
-methods, such as ``POST``, ``PUT``, ``PATCH`` and ``DELETE``. The ``route()``
-decorator takes a ``methods`` optional argument, in which the application can
-provide a list of HTTP methods that the route should be associated with on the
-given path.
-
-The following example defines a route that handles ``GET`` and ``POST``
-requests within the same function::
-
-    @app.route('/invoices', methods=['GET', 'POST'])
-    async def invoices(request):
-        if request.method == 'GET':
-            return 'get invoices'
-        elif request.method == 'POST':
-            return 'create an invoice'
-
-As an alternative to the example above, in which a single function is used to
-handle multiple HTTP methods, sometimes it may be desirable to write a separate
-function for each HTTP method. The above example can be implemented with two
-routes as follows::
-
-    @app.route('/invoices', methods=['GET'])
-    async def get_invoices(request):
-        return 'get invoices'
-
-    @app.route('/invoices', methods=['POST'])
-    async def create_invoice(request):
-        return 'create an invoice'
-
-Microdot provides the :func:`get() <microdot.Microdot.get>`,
-:func:`post() <microdot.Microdot.post>`, :func:`put() <microdot.Microdot.put>`,
-:func:`patch() <microdot.Microdot.patch>`, and
-:func:`delete() <microdot.Microdot.delete>` decorators as shortcuts for the
-corresponding HTTP methods. The two example routes above can be written more
-concisely with them::
-
-    @app.get('/invoices')
-    async def get_invoices(request):
-        return 'get invoices'
-
-    @app.post('/invoices')
-    async def create_invoice(request):
-        return 'create an invoice'
-
-Including Dynamic Components in the URL Path
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-The examples shown above all use hardcoded URL paths. Microdot also supports
-the definition of routes that have dynamic components in the path. For example,
-the following route associates all URLs that have a path following the pattern
-*http://localhost:5000/users/<username>* with the ``get_user()`` function::
-
-    @app.get('/users/<username>')
-    async def get_user(request, username):
-        return 'User: ' + username
-
-As shown in the example, a path component that is enclosed in angle brackets
-is considered a placeholder. Microdot accepts any values for that portion of
-the URL path, and passes the value received to the function as an argument
-after the request object.
-
-Routes are not limited to a single dynamic component. The following route shows
-how multiple dynamic components can be included in the path::
-
-    @app.get('/users/<firstname>/<lastname>')
-    async def get_user(request, firstname, lastname):
-        return 'User: ' + firstname + ' ' + lastname
-
-Dynamic path components are considered to be strings by default. An explicit
-type can be specified as a prefix, separated from the dynamic component name by
-a colon. The following route has two dynamic components declared as an integer
-and a string respectively::
-
-    @app.get('/users/<int:id>/<string:username>')
-    async def get_user(request, id, username):
-        return 'User: ' + username + ' (' + str(id) + ')'
-
-If a dynamic path component is defined as an integer, the value passed to the
-route function is also an integer. If the client sends a value that is not an
-integer in the corresponding section of the URL path, then the URL will not
-match and the route will not be called.
-
-A special type ``path`` can be used to capture the remainder of the path as a
-single argument. The difference between an argument of type ``path`` and one of
-type ``string`` is that the latter stops capturing when a ``/`` appears in the
-URL::
-
-    @app.get('/tests/<path:path>')
-    async def get_test(request, path):
-        return 'Test: ' + path
-
-The ``re`` type allows the application to provide a custom regular expression
-for the dynamic component. The next example defines a route that only matches
-usernames that begin with an upper or lower case letter, followed by a sequence
-of letters or numbers::
-
-    @app.get('/users/<re:[a-zA-Z][a-zA-Z0-9]*:username>')
-    async def get_user(request, username):
-        return 'User: ' + username
-
-The ``re`` type returns the URL component as a string, which sometimes may not
-be the most convenient. To convert a path component to something more
-meaningful than a string, the application can register a custom URL component
-type and provide a parser function that performs the conversion. In the
-following example, a ``hex`` custom type is registered to automatically
-convert hex numbers given in the path to numbers::
-
-    from microdot import URLPattern
-
-    URLPattern.register_type('hex', parser=lambda value: int(value, 16))
-
-    @app.get('/users/<hex:user_id>')
-    async def get_user(request, user_id):
-        user = get_user_by_id(user_id)
-        # ...
-
-In addition to the parser, the custom URL component can include a pattern,
-given as a regular expression. When a pattern is provided, the URL component
-will only match if the regular expression matches the value passed in the URL.
-The ``hex`` example above can be expanded with a pattern as follows::
-
-    URLPattern.register_type('hex', pattern='[0-9a-fA-F]+',
-                             parser=lambda value: int(value, 16))
-
-In cases where a pattern isn't provided, or when the pattern is unable to
-filter out all invalid values, the parser function can return ``None`` to
-indicate a failed match. The next example shows how the parser for the ``hex``
-type can be expanded to do that::
-
-    def hex_parser(value):
-        try:
-            return int(value, 16)
-        except ValueError:
-            return None
-
-    URLPattern.register_type('hex', parser=hex_parser)
-
-.. note::
-   Dynamic path components are passed to route functions as keyword arguments,
-   so the names of the function arguments must match the names declared in the
-   path specification.
-
-Before and After Request Handlers
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-It is common for applications to need to perform one or more actions before a
-request is handled. Examples include authenticating and/or authorizing the
-client, opening a connection to a database, or checking if the requested
-resource can be obtained from a cache. The
-:func:`before_request() <microdot.Microdot.before_request>` decorator registers
-a function to be called before the request is dispatched to the route function.
-
-The following example registers a before-request handler that ensures that the
-client is authenticated before the request is handled::
-
-    @app.before_request
-    async def authenticate(request):
-        user = authorize(request)
-        if not user:
-            return 'Unauthorized', 401
-        request.g.user = user
-
-Before-request handlers receive the request object as an argument. If the
-function returns a value, Microdot sends it to the client as the response, and
-does not invoke the route function. This gives before-request handlers the
-power to intercept a request if necessary. The example above uses this
-technique to prevent an unauthorized user from accessing the requested
-route.
-
-After-request handlers registered with the
-:func:`after_request() <microdot.Microdot.after_request>` decorator are called
-after the route function returns a response. Their purpose is to perform any
-common closing or cleanup tasks. The next example shows a combination of
-before- and after-request handlers that print the time it takes for a request
-to be handled::
-
-    @app.before_request
-    async def start_timer(request):
-        request.g.start_time = time.time()
-
-    @app.after_request
-    async def end_timer(request, response):
-        duration = time.time() - request.g.start_time
-        print(f'Request took {duration:0.2f} seconds')
-
-After-request handlers receive the request and response objects as arguments,
-and they can return a modified response object to replace the original. If
-no value is returned from an after-request handler, then the original response
-object is used.
-
-The after-request handlers are only invoked for successful requests. The
-:func:`after_error_request() <microdot.Microdot.after_error_request>`
-decorator can be used to register a function that is called after an error
-occurs. The function receives the request and the error response and is
-expected to return an updated response object after performing any necessary
-cleanup.
-
-.. note::
-   The :ref:`request.g <The "g" Object>` object used in many of the above
-   examples is a special object that allows the before- and after-request
-   handlers, as well as the route function to share data during the life of the
-   request.
-
-Error Handlers
-^^^^^^^^^^^^^^
-
-When an error occurs during the handling of a request, Microdot ensures that
-the client receives an appropriate error response. Some of the common errors
-automatically handled by Microdot are:
-
-- 400 for malformed requests.
-- 404 for URLs that are unknown.
-- 405 for URLs that are known, but not implemented for the requested HTTP
-  method.
-- 413 for requests that are larger than the allowed size.
-- 500 when the application raises an unhandled exception.
-
-While the above errors are fully complaint with the HTTP specification, the
-application might want to provide custom responses for them. The
-:func:`errorhandler() <microdot.Microdot.errorhandler>` decorator registers
-functions to respond to specific error codes. The following example shows a
-custom error handler for 404 errors::
-
-    @app.errorhandler(404)
-    async def not_found(request):
-        return {'error': 'resource not found'}, 404
-
-The ``errorhandler()`` decorator has a second form, in which it takes an
-exception class as an argument. Microdot will invoke the handler when an
-unhandled exception that is an instance of the given class is raised. The next
-example provides a custom response for division by zero errors::
-
-    @app.errorhandler(ZeroDivisionError)
-    async def division_by_zero(request, exception):
-        return {'error': 'division by zero'}, 500
-
-When the raised exception class does not have an error handler defined, but
-one or more of its parent classes do, Microdot makes an attempt to invoke the
-most specific handler.
-
-Mounting a Sub-Application
-^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Small Microdot applications can be written as a single source file, but this
-is not the best option for applications that pass a certain size. To make it
-simpler to write large applications, Microdot supports the concept of
-sub-applications that can be "mounted" on a larger application, possibly with
-a common URL prefix applied to all of its routes. For developers familiar with
-the Flask framework, this is a similar concept to Flask's blueprints.
-
-Consider, for example, a *customers.py* sub-application that implements
-operations on customers::
-
-    from microdot import Microdot
-
-    customers_app = Microdot()
-
-    @customers_app.get('/')
-    async def get_customers(request):
-        # return all customers
-
-    @customers_app.post('/')
-    async def new_customer(request):
-        # create a new customer
-
-Similar to the above, the *orders.py* sub-application implements operations on
-customer orders::
-
-    from microdot import Microdot
-
-    orders_app = Microdot()
-
-    @orders_app.get('/')
-    async def get_orders(request):
-        # return all orders
-
-    @orders_app.post('/')
-    async def new_order(request):
-        # create a new order
-
-Now the main application, which is stored in *main.py*, can import and mount
-the sub-applications to build the larger combined application::
-
-    from microdot import Microdot
-    from customers import customers_app
-    from orders import orders_app
-
-    def create_app():
-        app = Microdot()
-        app.mount(customers_app, url_prefix='/customers')
-        app.mount(orders_app, url_prefix='/orders')
-        return app
-
-    app = create_app()
-    app.run()
-
-The resulting application will have the customer endpoints available at
-*/customers/* and the order endpoints available at */orders/*.
-
-.. note::
-   During the handling of a request, the
-   :attr:`Request.url_prefix <microdot.Microdot.url_prefix>` attribute is
-   set to the URL prefix under which the sub-application was mounted, or an
-   empty string if the endpoint did not come from a sub-application or the
-   sub-application was mounted without a URL prefix. It is possible to issue a
-   redirect that is relative to the sub-application as follows::
-
-      return redirect(request.url_prefix + '/relative-url')
-
-When mounting an application as shown above, before-request, after-request and
-error handlers defined in the sub-application are copied over to the main
-application at mount time. Once installed in the main application, these
-handlers will apply to the whole application and not just the sub-application
-in which they were created.
-
-The :func:`mount() <microdot.Microdot.mount>` method has a ``local`` argument
-that defaults to ``False``. When this argument is set to ``True``, the
-before-request, after-request and error handlers defined in the sub-application
-will only apply to the sub-application.
-
-Shutting Down the Server
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-Web servers are designed to run forever, and are often stopped by sending them
-an interrupt signal. But having a way to gracefully stop the server is
-sometimes useful, especially in testing environments. Microdot provides a
-:func:`shutdown() <microdot.Microdot.shutdown>` method that can be invoked
-during the handling of a route to gracefully shut down the server when that
-request completes. The next example shows how to use this feature::
-
-    @app.get('/shutdown')
-    async def shutdown(request):
-        request.app.shutdown()
-        return 'The server is shutting down...'
-
-The request that invokes the ``shutdown()`` method will complete, and then the
-server will not accept any new requests and stop once any remaining requests
-complete. At this point the ``app.run()`` call will return.
-
-The Request Object
-~~~~~~~~~~~~~~~~~~
-
-The :class:`Request <microdot.Request>` object encapsulates all the information
-passed by the client. It is passed as an argument to route handlers, as well as
-to before-request, after-request and error handlers.
-
-Request Attributes
-^^^^^^^^^^^^^^^^^^
-
-The request object provides access to the request attributes, including:
-
-- :attr:`method <microdot.Request.method>`: The HTTP method of the request.
-- :attr:`path <microdot.Request.path>`: The path of the request.
-- :attr:`args <microdot.Request.args>`: The query string parameters of the
-  request, as a :class:`MultiDict <microdot.MultiDict>` object.
-- :attr:`headers <microdot.Request.headers>`: The headers of the request, as a
-  dictionary.
-- :attr:`cookies <microdot.Request.cookies>`: The cookies that the client sent
-  with the request, as a dictionary.
-- :attr:`content_type <microdot.Request.content_type>`: The content type
-  specified by the client, or ``None`` if no content type was specified.
-- :attr:`content_length <microdot.Request.content_length>`: The content
-  length of the request, or 0 if no content length was specified.
-- :attr:`json <microdot.Request.json>`: The parsed JSON data in the request
-  body. See :ref:`below <JSON Payloads>` for additional details.
-- :attr:`form <microdot.Request.form>`: The parsed form data in the request
-  body, as a dictionary. See :ref:`below <Form Data>` for additional details.
-- :attr:`files <microdot.Request.files>`: A dictionary with the file uploads
-  included in the request body. Note that file uploads are only supported when
-  the :ref:`Multipart Forms` extension is used.
-- :attr:`client_addr <microdot.Request.client_addr>`: The network address of
-  the client, as a tuple (host, port).
-- :attr:`app <microdot.Request.app>`: The application instance that created the
-  request.
-- :attr:`g <microdot.Request.g>`: The ``g`` object, where handlers can store
-  request-specific data to be shared among handlers. See :ref:`The "g" Object`
-  for details.
-
-JSON Payloads
-^^^^^^^^^^^^^
-
-When the client sends a request that contains JSON data in the body, the
-application can access the parsed JSON data using the
-:attr:`json <microdot.Request.json>` attribute. The following example shows how
-to use this attribute::
-
-    @app.post('/customers')
-    async def create_customer(request):
-        customer = request.json
-        # do something with customer
-        return {'success': True}
-
-.. note::
-   The client must set the ``Content-Type`` header to ``application/json`` for
-   the ``json`` attribute of the request object to be populated.
-
-Form Data
-^^^^^^^^^
-
-The request object also supports standard HTML form submissions through the
-:attr:`form <microdot.Request.form>` attribute, which presents the form data
-as a :class:`MultiDict <microdot.MultiDict>` object. Example::
-
-    @app.route('/', methods=['GET', 'POST'])
-    async def index(req):
-        name = 'Unknown'
-        if req.method == 'POST':
-            name = req.form.get('name')
-        return f'Hello {name}'
-
-.. note::
-   Form submissions automatically parsed when the ``Content-Type`` header is
-   set by the client to ``application/x-www-form-urlencoded``. For form
-   submissions that use the ``multipart/form-data`` content type the
-   :ref:`Multipart Forms` extension must be used.
-
-Accessing the Raw Request Body
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-For cases in which neither JSON nor form data is expected, the
-:attr:`body <microdot.Request.body>` request attribute returns the entire body
-of the request as a byte sequence.
-
-If the expected body is too large to fit safely in memory, the application can
-use the :attr:`stream <microdot.Request.stream>` request attribute to read the
-body contents as a file-like object. The
-:attr:`max_body_length <microdot.Request.max_body_length>` attribute of the
-request object defines the size at which bodies are streamed instead of loaded
-into memory.
-
-Cookies
-^^^^^^^
-
-Cookies that are sent by the client are made available through the
-:attr:`cookies <microdot.Request.cookies>` attribute of the request object in
-dictionary form.
-
-The "g" Object
-^^^^^^^^^^^^^^
-
-Sometimes applications need to store data during the lifetime of a request, so
-that it can be shared between the before- and after-request handlers, the
-route function and any error handlers. The request object provides the
-:attr:`g <microdot.Request.g>` attribute for that purpose.
-
-In the following example, a before request handler authorizes the client and
-stores the username so that the route function can use it::
-
-    @app.before_request
-    async def authorize(request):
-        username = authenticate_user(request)
-        if not username:
-            return 'Unauthorized', 401
-        request.g.username = username
-
-    @app.get('/')
-    async def index(request):
-        return f'Hello, {request.g.username}!'
-
-Request-Specific After-Request Handlers
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Sometimes applications need to perform operations on the response object
-before it is sent to the client, for example to set or remove a cookie. A good
-option to use for this is to define a request-specific after-request handler
-using the :func:`after_request <microdot.Microdot.after_request>` decorator.
-Request-specific after-request handlers are called by Microdot after the route
-function returns and all the application-wide after-request handlers have been
-called.
-
-The next example shows how a cookie can be updated using a request-specific
-after-request handler defined inside a route function::
-
-    @app.post('/logout')
-    async def logout(request):
-        @request.after_request
-        def reset_session(request, response):
-            response.set_cookie('session', '', http_only=True)
-            return response
-
-        return 'Logged out'
-
-Request Limits
-^^^^^^^^^^^^^^
-
-To help prevent malicious attacks, Microdot provides some configuration options
-to limit the amount of information that is accepted:
-
-- :attr:`max_content_length <microdot.Request.max_content_length>`: The
-  maximum size accepted for the request body, in bytes. When a client sends a
-  request that is larger than this, the server will respond with a 413 error.
-  The default is 16KB.
-- :attr:`max_body_length <microdot.Request.max_body_length>`: The maximum
-  size that is loaded in the :attr:`body <microdot.Request.body>` attribute, in
-  bytes. Requests that have a body that is larger than this size but smaller
-  than the size set for ``max_content_length`` can only be accessed through the
-  :attr:`stream <microdot.Request.stream>` attribute. The default is also 16KB.
-- :attr:`max_readline <microdot.Request.max_readline>`: The maximum allowed
-  size for a request line, in bytes. The default is 2KB.
-
-The following example configures the application to accept requests with
-payloads up to 1MB in size, but prevents requests that are larger than 8KB from
-being loaded into memory::
-
-    from microdot import Request
-
-    Request.max_content_length = 1024 * 1024
-    Request.max_body_length = 8 * 1024
-
-Responses
-~~~~~~~~~
-
-The value or values that are returned from the route function are used by
-Microdot to build the response that is sent to the client. The following
-sections describe the different types of responses that are supported.
-
-The Three Parts of a Response
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Route functions can return one, two or three values. The first and most
-important value is the response body::
-
-    @app.get('/')
-    async def index(request):
-        return 'Hello, World!'
-
-In the above example, Microdot issues a standard 200 status code response
-indicating a successful request. The body of the response is the
-``'Hello, World!'`` string returned by the function. Microdot includes default
-headers with this response, including the ``Content-Type`` header set to
-``text/plain`` to indicate a response in plain text.
-
-The application can provide its own status code as a second value returned from
-the route to override the 200 default. The example below returns a 202 status
-code::
-
-    @app.get('/')
-    async def index(request):
-        return 'Hello, World!', 202
-
-The application can also return a third value, a dictionary with additional
-headers that are added to, or replace the default ones included by Microdot.
-The next example returns an HTML response, instead of the default plain text
-response::
-
-    @app.get('/')
-    async def index(request):
-        return '<h1>Hello, World!</h1>', 202, {'Content-Type': 'text/html'}
-
-If the application does not need to return a body, then it can omit it and
-have the status code as the first or only returned value::
-
-    @app.get('/')
-    async def index(request):
-        return 204
-
-Likewise, if the application needs to return a body and custom headers, but
-does not need to change the default status code, then it can return two values,
-omitting the status code::
-
-    @app.get('/')
-    async def index(request):
-        return '<h1>Hello, World!</h1>', {'Content-Type': 'text/html'}
-
-Lastly, the application can also return a :class:`Response <microdot.Response>`
-object containing all the details of the response as a single value.
-
-JSON Responses
-^^^^^^^^^^^^^^
-
-If the application needs to return a response with JSON formatted data, it can
-return a dictionary or a list as the first value, and Microdot will
-automatically format the response as JSON.
-
-Example::
-
-    @app.get('/')
-    async def index(request):
-        return {'hello': 'world'}
-
-.. note::
-   A ``Content-Type`` header set to ``application/json`` is automatically added
-   to the response.
-
-Redirects
-^^^^^^^^^
-
-The :func:`redirect <microdot.Response.redirect>` function is a helper that
-creates redirect responses::
-
-    from microdot import redirect
-
-    @app.get('/')
-    async def index(request):
-        return redirect('/about')
-
-File Responses
-^^^^^^^^^^^^^^
-
-The :func:`send_file <microdot.Response.send_file>` function builds a response
-object for a file::
-
-        from microdot import send_file
-
-        @app.get('/')
-        async def index(request):
-            return send_file('/static/index.html')
-
-A suggested caching duration can be returned to the client in the ``max_age``
-argument::
-
-        from microdot import send_file
-
-        @app.get('/')
-        async def image(request):
-            return send_file('/static/image.jpg', max_age=3600)  # in seconds
-
-.. note::
-   Unlike other web frameworks, Microdot does not automatically configure a
-   route to serve static files. The following is an example route that can be
-   added to the application to serve static files from a *static* directory in
-   the project::
-
-        @app.route('/static/<path:path>')
-        async def static(request, path):
-            if '..' in path:
-                # directory traversal is not allowed
-                return 'Not found', 404
-            return send_file('static/' + path, max_age=86400)
-
-Streaming Responses
-^^^^^^^^^^^^^^^^^^^
-
-Instead of providing a response as a single value, an application can opt to
-return a response that is generated in chunks, by returning a Python generator.
-The example below returns all the numbers in the fibonacci sequence below 100::
-
-    @app.get('/fibonacci')
-    async def fibonacci(request):
-        async def generate_fibonacci():
-            a, b = 0, 1
-            while a < 100:
-                yield str(a) + '\n'
-                a, b = b, a + b
-
-        return generate_fibonacci()
-
-.. note::
-   Under CPython, the generator function can be a ``def`` or ``async def``
-   function, as well as a class-based generator.
-
-   Under MicroPython, asynchronous generator functions are not supported, so
-   only ``def`` generator functions can be used. Asynchronous class-based
-   generators are supported.
-
-Changing the Default Response Content Type
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Microdot uses a ``text/plain`` content type by default for responses that do
-not explicitly include the ``Content-Type`` header. The application can change
-this default by setting the desired content type in the
-:attr:`default_content_type <microdot.Response.default_content_type>` attribute
-of the :class:`Response <microdot.Response>` class.
-
-The example that follows configures the application to use ``text/html`` as
-default content type::
-
-    from microdot import Response
-
-    Response.default_content_type = 'text/html'
-
-Setting Cookies
-^^^^^^^^^^^^^^^
-
-Many web applications rely on cookies to maintain client state between
-requests. Cookies can be set with the ``Set-Cookie`` header in the response,
-but since this is such a common practice, Microdot provides the
-:func:`set_cookie() <microdot.Response.set_cookie>` method in the response
-object to add a properly formatted cookie header to the response.
-
-Given that route functions do not normally work directly with the response
-object, the recommended way to set a cookie is to do it in a
-:ref:`request-specific after-request handler <Request-Specific After-Request Handlers>`.
-
-Example::
-
-    @app.get('/')
-    async def index(request):
-        @request.after_request
-        async def set_cookie(request, response):
-            response.set_cookie('name', 'value')
-            return response
-
-        return 'Hello, World!'
-
-Another option is to create a response object directly in the route function::
-
-    @app.get('/')
-    async def index(request):
-        response = Response('Hello, World!')
-        response.set_cookie('name', 'value')
-        return response
-
-.. note::
-   Standard cookies do not offer sufficient privacy and security controls, so
-   never store sensitive information in them unless you are adding additional
-   protection mechanisms such as encryption or cryptographic signing. The
-   :ref:`session <Maintaining Secure User Sessions>` extension implements signed
-   cookies that prevent tampering by malicious actors.
-
-Concurrency
-~~~~~~~~~~~
-
-Microdot implements concurrency through the ``asyncio`` package, which means
-that applications must be careful to prevent blocking in their handlers.
-
-"async def" handlers
-^^^^^^^^^^^^^^^^^^^^
-
-The recommendation for route handlers in Microdot is to use asynchronous
-functions, declared as ``async def``. Microdot executes these handler
-functions as native asynchronous tasks. The standard considerations for writing
-asynchronous code apply, and in particular blocking calls should be avoided to
-ensure the application runs smoothly and is always responsive.
-
-"def" handlers
-^^^^^^^^^^^^^^
-
-Microdot also supports the use of synchronous route handlers, declared as
-standard ``def`` functions. These handlers are handled differently under
-CPython and MicroPython.
-
-When running on CPython, Microdot executes synchronous handlers in a
-`thread executor <https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.run_in_executor>`_,
-which uses a thread pool. The use of blocking or CPU intensive code in these
-handlers does not have such a negative effect on the application, because
-handlers do not run on the same thread as the asynchronous loop. On the other
-hand, the application will be affected by threading issues such as those caused
-by the Global Interpreter Lock.
-
-Under MicroPython the situation is different. Most microcontroller boards
-do not have or have very limited threading support, so Microdot executes
-synchronous handlers in the main and often only thread available. This means
-that these functions will block the asynchronous loop when they take too long
-to complete. The use of properly written asynchronous handlers should be
-preferred.

docs/users-guide/concurrency.rst

@@ -0,0 +1,36 @@
+Concurrency
+~~~~~~~~~~~
+
+Microdot implements concurrency through the ``asyncio`` package, which means
+that applications must be careful to prevent blocking in their handlers.
+
+"async def" handlers
+^^^^^^^^^^^^^^^^^^^^
+
+The recommendation for route handlers in Microdot is to use asynchronous
+functions, declared as ``async def``. Microdot executes these handler
+functions as native asynchronous tasks. The standard considerations for writing
+asynchronous code apply, and in particular blocking calls should be avoided to
+ensure the application runs smoothly and is always responsive.
+
+"def" handlers
+^^^^^^^^^^^^^^
+
+Microdot also supports the use of synchronous route handlers, declared as
+standard ``def`` functions. These handlers are handled differently under
+CPython and MicroPython.
+
+When running on CPython, Microdot executes synchronous handlers in a
+`thread executor <https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.run_in_executor>`_,
+which uses a thread pool. The use of blocking or CPU intensive code in these
+handlers does not have such a negative effect on the application, because
+handlers do not run on the same thread as the asynchronous loop. On the other
+hand, the application will be affected by threading issues such as those caused
+by the Global Interpreter Lock.
+
+Under MicroPython the situation is different. Most microcontroller boards
+do not have or have very limited threading support, so Microdot executes
+synchronous handlers in the main and often only thread available. This means
+that these functions will block the asynchronous loop when they take too long
+to complete. The use of properly written asynchronous handlers should be
+preferred.

docs/users-guide/defining-routes.rst

@@ -0,0 +1,378 @@
+Defining Routes
+~~~~~~~~~~~~~~~
+
+In Microdot, routes define the logic of the web application.
+
+The route decorator
+^^^^^^^^^^^^^^^^^^^
+The :func:`route() <microdot.Microdot.route>` decorator is used to associate an
+application URL with the function that handles it. The only required argument
+to the decorator is the path portion of the URL.
+
+The following example creates a route for the root URL of the application::
+
+    @app.route('/')
+    async def index(request):
+        return 'Hello, world!'
+
+When a client requests the root URL (for example, *http://localhost:5000/*),
+Microdot will call the ``index()`` function, passing it a
+:class:`Request <microdot.Request>` object. The return value of the function
+is the response that is sent to the client.
+
+Below is another example, this one with a route for a URL with two components
+in its path::
+
+    @app.route('/users/active')
+    async def active_users(request):
+        return 'Active users: Susan, Joe, and Bob'
+
+The complete URL that maps to this route is
+*http://localhost:5000/users/active*.
+
+An application can define multiple routes. Microdot uses the path portion of
+the URL to determine the correct route function to call for each incoming
+request.
+
+Choosing the HTTP Method
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+All the example routes shown above are associated with ``GET`` requests, which
+are the default. Applications often need to define routes for other HTTP
+methods, such as ``POST``, ``PUT``, ``PATCH`` and ``DELETE``. The ``route()``
+decorator takes a ``methods`` optional argument, in which the application can
+provide a list of HTTP methods that the route should be associated with on the
+given path.
+
+The following example defines a route that handles ``GET`` and ``POST``
+requests within the same function::
+
+    @app.route('/invoices', methods=['GET', 'POST'])
+    async def invoices(request):
+        if request.method == 'GET':
+            return 'get invoices'
+        elif request.method == 'POST':
+            return 'create an invoice'
+
+As an alternative to the example above, in which a single function is used to
+handle multiple HTTP methods, sometimes it may be desirable to write a separate
+function for each HTTP method. The above example can be implemented with two
+routes as follows::
+
+    @app.route('/invoices', methods=['GET'])
+    async def get_invoices(request):
+        return 'get invoices'
+
+    @app.route('/invoices', methods=['POST'])
+    async def create_invoice(request):
+        return 'create an invoice'
+
+Microdot provides the :func:`get() <microdot.Microdot.get>`,
+:func:`post() <microdot.Microdot.post>`, :func:`put() <microdot.Microdot.put>`,
+:func:`patch() <microdot.Microdot.patch>`, and
+:func:`delete() <microdot.Microdot.delete>` decorators as shortcuts for the
+corresponding HTTP methods. The two example routes above can be written more
+concisely with them::
+
+    @app.get('/invoices')
+    async def get_invoices(request):
+        return 'get invoices'
+
+    @app.post('/invoices')
+    async def create_invoice(request):
+        return 'create an invoice'
+
+Including Dynamic Components in the URL Path
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The examples shown above all use hardcoded URL paths. Microdot also supports
+the definition of routes that have dynamic components in the path. For example,
+the following route associates all URLs that have a path following the pattern
+*http://localhost:5000/users/<username>* with the ``get_user()`` function::
+
+    @app.get('/users/<username>')
+    async def get_user(request, username):
+        return 'User: ' + username
+
+As shown in the example, a path component that is enclosed in angle brackets
+is considered a placeholder. Microdot accepts any values for that portion of
+the URL path, and passes the value received to the function as an argument
+after the request object.
+
+Routes are not limited to a single dynamic component. The following route shows
+how multiple dynamic components can be included in the path::
+
+    @app.get('/users/<firstname>/<lastname>')
+    async def get_user(request, firstname, lastname):
+        return 'User: ' + firstname + ' ' + lastname
+
+Dynamic path components are considered to be strings by default. An explicit
+type can be specified as a prefix, separated from the dynamic component name by
+a colon. The following route has two dynamic components declared as an integer
+and a string respectively::
+
+    @app.get('/users/<int:id>/<string:username>')
+    async def get_user(request, id, username):
+        return 'User: ' + username + ' (' + str(id) + ')'
+
+If a dynamic path component is defined as an integer, the value passed to the
+route function is also an integer. If the client sends a value that is not an
+integer in the corresponding section of the URL path, then the URL will not
+match and the route will not be called.
+
+A special type ``path`` can be used to capture the remainder of the path as a
+single argument. The difference between an argument of type ``path`` and one of
+type ``string`` is that the latter stops capturing when a ``/`` appears in the
+URL::
+
+    @app.get('/tests/<path:path>')
+    async def get_test(request, path):
+        return 'Test: ' + path
+
+The ``re`` type allows the application to provide a custom regular expression
+for the dynamic component. The next example defines a route that only matches
+usernames that begin with an upper or lower case letter, followed by a sequence
+of letters or numbers::
+
+    @app.get('/users/<re:[a-zA-Z][a-zA-Z0-9]*:username>')
+    async def get_user(request, username):
+        return 'User: ' + username
+
+The ``re`` type returns the URL component as a string, which sometimes may not
+be the most convenient. To convert a path component to something more
+meaningful than a string, the application can register a custom URL component
+type and provide a parser function that performs the conversion. In the
+following example, a ``hex`` custom type is registered to automatically
+convert hex numbers given in the path to numbers::
+
+    from microdot import URLPattern
+
+    URLPattern.register_type('hex', parser=lambda value: int(value, 16))
+
+    @app.get('/users/<hex:user_id>')
+    async def get_user(request, user_id):
+        user = get_user_by_id(user_id)
+        # ...
+
+In addition to the parser, the custom URL component can include a pattern,
+given as a regular expression. When a pattern is provided, the URL component
+will only match if the regular expression matches the value passed in the URL.
+The ``hex`` example above can be expanded with a pattern as follows::
+
+    URLPattern.register_type('hex', pattern='[0-9a-fA-F]+',
+                             parser=lambda value: int(value, 16))
+
+In cases where a pattern isn't provided, or when the pattern is unable to
+filter out all invalid values, the parser function can return ``None`` to
+indicate a failed match. The next example shows how the parser for the ``hex``
+type can be expanded to do that::
+
+    def hex_parser(value):
+        try:
+            return int(value, 16)
+        except ValueError:
+            return None
+
+    URLPattern.register_type('hex', parser=hex_parser)
+
+.. note::
+   Dynamic path components are passed to route functions as keyword arguments,
+   so the names of the function arguments must match the names declared in the
+   path specification.
+
+Before and After Request Handlers
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+It is common for applications to need to perform one or more actions before a
+request is handled. Examples include authenticating and/or authorizing the
+client, opening a connection to a database, or checking if the requested
+resource can be obtained from a cache. The
+:func:`before_request() <microdot.Microdot.before_request>` decorator registers
+a function to be called before the request is dispatched to the route function.
+
+The following example registers a before-request handler that ensures that the
+client is authenticated before the request is handled::
+
+    @app.before_request
+    async def authenticate(request):
+        user = authorize(request)
+        if not user:
+            return 'Unauthorized', 401
+        request.g.user = user
+
+Before-request handlers receive the request object as an argument. If the
+function returns a value, Microdot sends it to the client as the response, and
+does not invoke the route function. This gives before-request handlers the
+power to intercept a request if necessary. The example above uses this
+technique to prevent an unauthorized user from accessing the requested
+route.
+
+After-request handlers registered with the
+:func:`after_request() <microdot.Microdot.after_request>` decorator are called
+after the route function returns a response. Their purpose is to perform any
+common closing or cleanup tasks. The next example shows a combination of
+before- and after-request handlers that print the time it takes for a request
+to be handled::
+
+    @app.before_request
+    async def start_timer(request):
+        request.g.start_time = time.time()
+
+    @app.after_request
+    async def end_timer(request, response):
+        duration = time.time() - request.g.start_time
+        print(f'Request took {duration:0.2f} seconds')
+
+After-request handlers receive the request and response objects as arguments,
+and they can return a modified response object to replace the original. If
+no value is returned from an after-request handler, then the original response
+object is used.
+
+The after-request handlers are only invoked for successful requests. The
+:func:`after_error_request() <microdot.Microdot.after_error_request>`
+decorator can be used to register a function that is called after an error
+occurs. The function receives the request and the error response and is
+expected to return an updated response object after performing any necessary
+cleanup.
+
+.. note::
+   The :ref:`request.g <The "g" Object>` object used in many of the above
+   examples is a special object that allows the before- and after-request
+   handlers, as well as the route function to share data during the life of the
+   request.
+
+Error Handlers
+^^^^^^^^^^^^^^
+
+When an error occurs during the handling of a request, Microdot ensures that
+the client receives an appropriate error response. Some of the common errors
+automatically handled by Microdot are:
+
+- 400 for malformed requests.
+- 404 for URLs that are unknown.
+- 405 for URLs that are known, but not implemented for the requested HTTP
+  method.
+- 413 for requests that are larger than the allowed size.
+- 500 when the application raises an unhandled exception.
+
+While the above errors are fully complaint with the HTTP specification, the
+application might want to provide custom responses for them. The
+:func:`errorhandler() <microdot.Microdot.errorhandler>` decorator registers
+functions to respond to specific error codes. The following example shows a
+custom error handler for 404 errors::
+
+    @app.errorhandler(404)
+    async def not_found(request):
+        return {'error': 'resource not found'}, 404
+
+The ``errorhandler()`` decorator has a second form, in which it takes an
+exception class as an argument. Microdot will invoke the handler when an
+unhandled exception that is an instance of the given class is raised. The next
+example provides a custom response for division by zero errors::
+
+    @app.errorhandler(ZeroDivisionError)
+    async def division_by_zero(request, exception):
+        return {'error': 'division by zero'}, 500
+
+When the raised exception class does not have an error handler defined, but
+one or more of its parent classes do, Microdot makes an attempt to invoke the
+most specific handler.
+
+Mounting a Sub-Application
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Small Microdot applications can be written as a single source file, but this
+is not the best option for applications that pass a certain size. To make it
+simpler to write large applications, Microdot supports the concept of
+sub-applications that can be "mounted" on a larger application, possibly with
+a common URL prefix applied to all of its routes. For developers familiar with
+the Flask framework, this is a similar concept to Flask's blueprints.
+
+Consider, for example, a *customers.py* sub-application that implements
+operations on customers::
+
+    from microdot import Microdot
+
+    customers_app = Microdot()
+
+    @customers_app.get('/')
+    async def get_customers(request):
+        # return all customers
+
+    @customers_app.post('/')
+    async def new_customer(request):
+        # create a new customer
+
+Similar to the above, the *orders.py* sub-application implements operations on
+customer orders::
+
+    from microdot import Microdot
+
+    orders_app = Microdot()
+
+    @orders_app.get('/')
+    async def get_orders(request):
+        # return all orders
+
+    @orders_app.post('/')
+    async def new_order(request):
+        # create a new order
+
+Now the main application, which is stored in *main.py*, can import and mount
+the sub-applications to build the larger combined application::
+
+    from microdot import Microdot
+    from customers import customers_app
+    from orders import orders_app
+
+    def create_app():
+        app = Microdot()
+        app.mount(customers_app, url_prefix='/customers')
+        app.mount(orders_app, url_prefix='/orders')
+        return app
+
+    app = create_app()
+    app.run()
+
+The resulting application will have the customer endpoints available at
+*/customers/* and the order endpoints available at */orders/*.
+
+.. note::
+   During the handling of a request, the
+   :attr:`Request.url_prefix <microdot.Microdot.url_prefix>` attribute is
+   set to the URL prefix under which the sub-application was mounted, or an
+   empty string if the endpoint did not come from a sub-application or the
+   sub-application was mounted without a URL prefix. It is possible to issue a
+   redirect that is relative to the sub-application as follows::
+
+      return redirect(request.url_prefix + '/relative-url')
+
+When mounting an application as shown above, before-request, after-request and
+error handlers defined in the sub-application are copied over to the main
+application at mount time. Once installed in the main application, these
+handlers will apply to the whole application and not just the sub-application
+in which they were created.
+
+The :func:`mount() <microdot.Microdot.mount>` method has a ``local`` argument
+that defaults to ``False``. When this argument is set to ``True``, the
+before-request, after-request and error handlers defined in the sub-application
+will only apply to the sub-application.
+
+Shutting Down the Server
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+Web servers are designed to run forever, and are often stopped by sending them
+an interrupt signal. But having a way to gracefully stop the server is
+sometimes useful, especially in testing environments. Microdot provides a
+:func:`shutdown() <microdot.Microdot.shutdown>` method that can be invoked
+during the handling of a route to gracefully shut down the server when that
+request completes. The next example shows how to use this feature::
+
+    @app.get('/shutdown')
+    async def shutdown(request):
+        request.app.shutdown()
+        return 'The server is shutting down...'
+
+The request that invokes the ``shutdown()`` method will complete, and then the
+server will not accept any new requests and stop once any remaining requests
+complete. At this point the ``app.run()`` call will return.

docs/users-guide/index.rst

@@ -0,0 +1,18 @@
+User's Guide
+------------
+
+This section describes the main features of Microdot.
+
+.. toctree::
+   :maxdepth: 1
+
+   intro
+   defining-routes
+   request-object
+   responses
+   concurrency
+
+For detailed reference information, consult the :ref:`API Reference`.
+
+If you are familiar with releases of Microdot before 2.x, review the
+:ref:`Migration Guide <Migrating to Microdot 2.x from Older Releases>`.

docs/users-guide/intro.rst

@@ -0,0 +1,160 @@
+Introduction
+~~~~~~~~~~~~
+
+This section covers how to create and run a basic Microdot web application.
+
+A simple web server
+^^^^^^^^^^^^^^^^^^^
+
+The following is an example of a simple web server::
+
+    from microdot import Microdot
+
+    app = Microdot()
+
+    @app.route('/')
+    async def index(request):
+        return 'Hello, world!'
+
+    app.run()
+
+The script imports the :class:`Microdot <microdot.Microdot>` class and creates
+an application instance from it.
+
+The application instance provides a :func:`route() <microdot.Microdot.route>`
+decorator, which is used to define one or more routes, as needed by the
+application.
+
+The ``route()`` decorator takes the path portion of the URL as an
+argument, and maps it to the decorated function, so that the function is called
+when the client requests the URL.
+
+When the function is called, it is passed a :class:`Request <microdot.Request>`
+object as an argument, which provides access to the information passed by the
+client. The value returned by the function is sent back to the client as the
+response.
+
+Microdot is an asynchronous framework that uses the ``asyncio`` package. Route
+handler functions can be defined as ``async def`` or ``def`` functions, but
+``async def`` functions are recommended for performance.
+
+The :func:`run() <microdot.Microdot.run>` method starts the application's web
+server on port 5000 by default, and creates its own asynchronous loop. This
+method blocks while it waits for connections from clients.
+
+For some applications it may be necessary to run the web server alongside other
+asynchronous tasks, on an already running loop. In that case, instead of
+``app.run()`` the web server can be started by invoking the
+:func:`start_server() <microdot.Microdot.start_server>` coroutine as shown in
+the following example::
+
+    import asyncio
+    from microdot import Microdot
+
+    app = Microdot()
+
+    @app.route('/')
+    async def index(request):
+        return 'Hello, world!'
+
+    async def main():
+        # start the server in a background task
+        server = asyncio.create_task(app.start_server())
+
+        # ... do other asynchronous work here ...
+
+        # cleanup before ending the application
+        await server
+
+    asyncio.run(main())
+
+Running with CPython
+^^^^^^^^^^^^^^^^^^^^
+
+.. list-table::
+   :align: left
+
+   * - Required Microdot source files
+     - | `microdot.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/microdot.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello.py>`_
+
+When using CPython, you can start the web server by running the script that
+has the ``app.run()`` call at the bottom::
+
+    python main.py
+
+After starting the script, open a web browser and navigate to
+*http://localhost:5000/* to access the application at the default address for
+the Microdot web server. From other computers in the same network, use the IP
+address or hostname of the computer running the script instead of
+``localhost``.
+
+Running with MicroPython
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. list-table::
+   :align: left
+
+   * - Required Microdot source files
+     - | `microdot.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/microdot.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello.py>`_
+       | `gpio.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/gpio/gpio.py>`_
+
+When using MicroPython, you can upload a *main.py* file containing the web
+server code to your device, along with the required Microdot files, as defined
+in the :ref:`MicroPython Installation` section.
+
+MicroPython will automatically run *main.py* when the device is powered on, so
+the web server will automatically start. The application can be accessed on
+port 5000 at the device's IP address. As indicated above, the port can be
+changed by passing the ``port`` argument to the ``run()`` method.
+
+.. note::
+   Microdot does not configure the network interface of the device in which it
+   is running. If your device requires a network connection to be made in
+   advance, for example to a Wi-Fi access point, this must be configured before
+   the ``run()`` method is invoked.
+
+Web Server Configuration
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+The :func:`run() <microdot.Microdot.run>` and
+:func:`start_server() <microdot.Microdot.start_server>` methods support a few
+arguments to configure the web server.
+
+- ``port``: The port number to listen on. Pass the desired port number in this
+  argument to use a port different than the default of 5000. For example::
+
+    app.run(port=6000)
+
+- ``host``: The IP address of the network interface to listen on. By default
+  the server listens on all available interfaces. To listen only on the local
+  loopback interface, pass ``'127.0.0.1'`` as value for this argument.
+- ``debug``: when set to ``True``, the server ouputs logging information to the
+  console. The default is ``False``.
+- ``ssl``: an ``SSLContext`` instance that configures the server to use TLS
+  encryption, or ``None`` to disable TLS use. The default is ``None``. The
+  following example demonstrates how to configure the server with an SSL
+  certificate stored in *cert.pem* and *key.pem* files::
+
+    import ssl
+
+    # ...
+
+    sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
+    sslctx.load_cert_chain('cert.pem', 'key.pem')
+    app.run(port=4443, debug=True, ssl=sslctx)
+
+.. note::
+   When using CPython, the certificate and key files must be given in PEM
+   format. When using MicroPython, these files must be given in DER format.

docs/users-guide/request-object.rst

@@ -0,0 +1,169 @@
+The Request Object
+~~~~~~~~~~~~~~~~~~
+
+The :class:`Request <microdot.Request>` object encapsulates all the information
+passed by the client. It is passed as an argument to route handlers, as well as
+to before-request, after-request and error handlers.
+
+Request Attributes
+^^^^^^^^^^^^^^^^^^
+
+The request object provides access to the request attributes, including:
+
+- :attr:`method <microdot.Request.method>`: The HTTP method of the request.
+- :attr:`path <microdot.Request.path>`: The path of the request.
+- :attr:`args <microdot.Request.args>`: The query string parameters of the
+  request, as a :class:`MultiDict <microdot.MultiDict>` object.
+- :attr:`headers <microdot.Request.headers>`: The headers of the request, as a
+  dictionary.
+- :attr:`cookies <microdot.Request.cookies>`: The cookies that the client sent
+  with the request, as a dictionary.
+- :attr:`content_type <microdot.Request.content_type>`: The content type
+  specified by the client, or ``None`` if no content type was specified.
+- :attr:`content_length <microdot.Request.content_length>`: The content
+  length of the request, or 0 if no content length was specified.
+- :attr:`json <microdot.Request.json>`: The parsed JSON data in the request
+  body. See :ref:`below <JSON Payloads>` for additional details.
+- :attr:`form <microdot.Request.form>`: The parsed form data in the request
+  body, as a dictionary. See :ref:`below <Form Data>` for additional details.
+- :attr:`files <microdot.Request.files>`: A dictionary with the file uploads
+  included in the request body. Note that file uploads are only supported when
+  the :ref:`Multipart Forms` extension is used.
+- :attr:`client_addr <microdot.Request.client_addr>`: The network address of
+  the client, as a tuple (host, port).
+- :attr:`app <microdot.Request.app>`: The application instance that created the
+  request.
+- :attr:`g <microdot.Request.g>`: The ``g`` object, where handlers can store
+  request-specific data to be shared among handlers. See :ref:`The "g" Object`
+  for details.
+
+JSON Payloads
+^^^^^^^^^^^^^
+
+When the client sends a request that contains JSON data in the body, the
+application can access the parsed JSON data using the
+:attr:`json <microdot.Request.json>` attribute. The following example shows how
+to use this attribute::
+
+    @app.post('/customers')
+    async def create_customer(request):
+        customer = request.json
+        # do something with customer
+        return {'success': True}
+
+.. note::
+   The client must set the ``Content-Type`` header to ``application/json`` for
+   the ``json`` attribute of the request object to be populated.
+
+Form Data
+^^^^^^^^^
+
+The request object also supports standard HTML form submissions through the
+:attr:`form <microdot.Request.form>` attribute, which presents the form data
+as a :class:`MultiDict <microdot.MultiDict>` object. Example::
+
+    @app.route('/', methods=['GET', 'POST'])
+    async def index(req):
+        name = 'Unknown'
+        if req.method == 'POST':
+            name = req.form.get('name')
+        return f'Hello {name}'
+
+.. note::
+   Form submissions automatically parsed when the ``Content-Type`` header is
+   set by the client to ``application/x-www-form-urlencoded``. For form
+   submissions that use the ``multipart/form-data`` content type the
+   :ref:`Multipart Forms` extension must be used.
+
+Accessing the Raw Request Body
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+For cases in which neither JSON nor form data is expected, the
+:attr:`body <microdot.Request.body>` request attribute returns the entire body
+of the request as a byte sequence.
+
+If the expected body is too large to fit safely in memory, the application can
+use the :attr:`stream <microdot.Request.stream>` request attribute to read the
+body contents as a file-like object. The
+:attr:`max_body_length <microdot.Request.max_body_length>` attribute of the
+request object defines the size at which bodies are streamed instead of loaded
+into memory.
+
+Cookies
+^^^^^^^
+
+Cookies that are sent by the client are made available through the
+:attr:`cookies <microdot.Request.cookies>` attribute of the request object in
+dictionary form.
+
+The "g" Object
+^^^^^^^^^^^^^^
+
+Sometimes applications need to store data during the lifetime of a request, so
+that it can be shared between the before- and after-request handlers, the
+route function and any error handlers. The request object provides the
+:attr:`g <microdot.Request.g>` attribute for that purpose.
+
+In the following example, a before request handler authorizes the client and
+stores the username so that the route function can use it::
+
+    @app.before_request
+    async def authorize(request):
+        username = authenticate_user(request)
+        if not username:
+            return 'Unauthorized', 401
+        request.g.username = username
+
+    @app.get('/')
+    async def index(request):
+        return f'Hello, {request.g.username}!'
+
+Request-Specific After-Request Handlers
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Sometimes applications need to perform operations on the response object
+before it is sent to the client, for example to set or remove a cookie. A good
+option to use for this is to define a request-specific after-request handler
+using the :func:`after_request <microdot.Microdot.after_request>` decorator.
+Request-specific after-request handlers are called by Microdot after the route
+function returns and all the application-wide after-request handlers have been
+called.
+
+The next example shows how a cookie can be updated using a request-specific
+after-request handler defined inside a route function::
+
+    @app.post('/logout')
+    async def logout(request):
+        @request.after_request
+        def reset_session(request, response):
+            response.set_cookie('session', '', http_only=True)
+            return response
+
+        return 'Logged out'
+
+Request Limits
+^^^^^^^^^^^^^^
+
+To help prevent malicious attacks, Microdot provides some configuration options
+to limit the amount of information that is accepted:
+
+- :attr:`max_content_length <microdot.Request.max_content_length>`: The
+  maximum size accepted for the request body, in bytes. When a client sends a
+  request that is larger than this, the server will respond with a 413 error.
+  The default is 16KB.
+- :attr:`max_body_length <microdot.Request.max_body_length>`: The maximum
+  size that is loaded in the :attr:`body <microdot.Request.body>` attribute, in
+  bytes. Requests that have a body that is larger than this size but smaller
+  than the size set for ``max_content_length`` can only be accessed through the
+  :attr:`stream <microdot.Request.stream>` attribute. The default is also 16KB.
+- :attr:`max_readline <microdot.Request.max_readline>`: The maximum allowed
+  size for a request line, in bytes. The default is 2KB.
+
+The following example configures the application to accept requests with
+payloads up to 1MB in size, but prevents requests that are larger than 8KB from
+being loaded into memory::
+
+    from microdot import Request
+
+    Request.max_content_length = 1024 * 1024
+    Request.max_body_length = 8 * 1024

docs/users-guide/responses.rst

@@ -0,0 +1,200 @@
+Responses
+~~~~~~~~~
+
+The value or values that are returned from the route function are used by
+Microdot to build the response that is sent to the client. The following
+sections describe the different types of responses that are supported.
+
+The Three Parts of a Response
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Route functions can return one, two or three values. The first and most
+important value is the response body::
+
+    @app.get('/')
+    async def index(request):
+        return 'Hello, World!'
+
+In the above example, Microdot issues a standard 200 status code response
+indicating a successful request. The body of the response is the
+``'Hello, World!'`` string returned by the function. Microdot includes default
+headers with this response, including the ``Content-Type`` header set to
+``text/plain`` to indicate a response in plain text.
+
+The application can provide its own status code as a second value returned from
+the route to override the 200 default. The example below returns a 202 status
+code::
+
+    @app.get('/')
+    async def index(request):
+        return 'Hello, World!', 202
+
+The application can also return a third value, a dictionary with additional
+headers that are added to, or replace the default ones included by Microdot.
+The next example returns an HTML response, instead of the default plain text
+response::
+
+    @app.get('/')
+    async def index(request):
+        return '<h1>Hello, World!</h1>', 202, {'Content-Type': 'text/html'}
+
+If the application does not need to return a body, then it can omit it and
+have the status code as the first or only returned value::
+
+    @app.get('/')
+    async def index(request):
+        return 204
+
+Likewise, if the application needs to return a body and custom headers, but
+does not need to change the default status code, then it can return two values,
+omitting the status code::
+
+    @app.get('/')
+    async def index(request):
+        return '<h1>Hello, World!</h1>', {'Content-Type': 'text/html'}
+
+Lastly, the application can also return a :class:`Response <microdot.Response>`
+object containing all the details of the response as a single value.
+
+JSON Responses
+^^^^^^^^^^^^^^
+
+If the application needs to return a response with JSON formatted data, it can
+return a dictionary or a list as the first value, and Microdot will
+automatically format the response as JSON.
+
+Example::
+
+    @app.get('/')
+    async def index(request):
+        return {'hello': 'world'}
+
+.. note::
+   A ``Content-Type`` header set to ``application/json`` is automatically added
+   to the response.
+
+Redirects
+^^^^^^^^^
+
+The :func:`redirect <microdot.Response.redirect>` function is a helper that
+creates redirect responses::
+
+    from microdot import redirect
+
+    @app.get('/')
+    async def index(request):
+        return redirect('/about')
+
+File Responses
+^^^^^^^^^^^^^^
+
+The :func:`send_file <microdot.Response.send_file>` function builds a response
+object for a file::
+
+        from microdot import send_file
+
+        @app.get('/')
+        async def index(request):
+            return send_file('/static/index.html')
+
+A suggested caching duration can be returned to the client in the ``max_age``
+argument::
+
+        from microdot import send_file
+
+        @app.get('/')
+        async def image(request):
+            return send_file('/static/image.jpg', max_age=3600)  # in seconds
+
+.. note::
+   Unlike other web frameworks, Microdot does not automatically configure a
+   route to serve static files. The following is an example route that can be
+   added to the application to serve static files from a *static* directory in
+   the project::
+
+        @app.route('/static/<path:path>')
+        async def static(request, path):
+            if '..' in path:
+                # directory traversal is not allowed
+                return 'Not found', 404
+            return send_file('static/' + path, max_age=86400)
+
+Streaming Responses
+^^^^^^^^^^^^^^^^^^^
+
+Instead of providing a response as a single value, an application can opt to
+return a response that is generated in chunks, by returning a Python generator.
+The example below returns all the numbers in the fibonacci sequence below 100::
+
+    @app.get('/fibonacci')
+    async def fibonacci(request):
+        async def generate_fibonacci():
+            a, b = 0, 1
+            while a < 100:
+                yield str(a) + '\n'
+                a, b = b, a + b
+
+        return generate_fibonacci()
+
+.. note::
+   Under CPython, the generator function can be a ``def`` or ``async def``
+   function, as well as a class-based generator.
+
+   Under MicroPython, asynchronous generator functions are not supported, so
+   only ``def`` generator functions can be used. Asynchronous class-based
+   generators are supported.
+
+Changing the Default Response Content Type
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Microdot uses a ``text/plain`` content type by default for responses that do
+not explicitly include the ``Content-Type`` header. The application can change
+this default by setting the desired content type in the
+:attr:`default_content_type <microdot.Response.default_content_type>` attribute
+of the :class:`Response <microdot.Response>` class.
+
+The example that follows configures the application to use ``text/html`` as
+default content type::
+
+    from microdot import Response
+
+    Response.default_content_type = 'text/html'
+
+Setting Cookies
+^^^^^^^^^^^^^^^
+
+Many web applications rely on cookies to maintain client state between
+requests. Cookies can be set with the ``Set-Cookie`` header in the response,
+but since this is such a common practice, Microdot provides the
+:func:`set_cookie() <microdot.Response.set_cookie>` method in the response
+object to add a properly formatted cookie header to the response.
+
+Given that route functions do not normally work directly with the response
+object, the recommended way to set a cookie is to do it in a
+:ref:`request-specific after-request handler <Request-Specific After-Request Handlers>`.
+
+Example::
+
+    @app.get('/')
+    async def index(request):
+        @request.after_request
+        async def set_cookie(request, response):
+            response.set_cookie('name', 'value')
+            return response
+
+        return 'Hello, World!'
+
+Another option is to create a response object directly in the route function::
+
+    @app.get('/')
+    async def index(request):
+        response = Response('Hello, World!')
+        response.set_cookie('name', 'value')
+        return response
+
+.. note::
+   Standard cookies do not offer sufficient privacy and security controls, so
+   never store sensitive information in them unless you are adding additional
+   protection mechanisms such as encryption or cryptographic signing. The
+   :ref:`session <Maintaining Secure User Sessions>` extension implements signed
+   cookies that prevent tampering by malicious actors.

examples/benchmark/requirements.txt

@@ -95,7 +95,7 @@ typing-extensions==4.9.0
     #   fastapi
     #   pydantic
     #   pydantic-core
-urllib3==2.5.0
+urllib3==2.6.0
     # via requests
 uvicorn==0.24.0.post1
     # via -r requirements.in

examples/csrf/README.md

@@ -0,0 +1,41 @@
+# CSRF Example
+
+This is a small example that demonstrates how the CSRF protection in Microdot
+works.
+
+## Running the example
+
+Start by cloning the repostory or copying the two example files *app.py* and
+*evil.py* to your computer. The only dependency these examples need to run is `microdot`, so create a virtual environment and run:
+
+    pip install microdot
+
+You need two terminals. On the first one, run:
+
+    python app.py
+
+To see the application open *http://localhost:5000* on your web browser. The
+application allows you to make payments through a web form. Each payment that
+you make reduces the balance in your account. Type an amount in the form field and press the "Issue Payment" button to see how the balance decreases.
+
+Leave the application running. On the second terminal run:
+
+    python evil.py
+
+Open a second browser tab and navigate to *http://localhost:5001*. This 
+application simulates a malicious web site that tries to steal money from your
+account. It does this by sending a cross-site form submission to the above
+application.
+
+The application presents a form that fools you into thinking you can win some
+money. Clicking the button triggers the cross-site request to the form in the
+first application, with the payment amount set to $100.
+
+Because the application has CSRF protection enabled, the cross-site request
+fails.
+
+If you want to see how the attack can succeed, open *app.py* in your editor and
+comment out the line that creates the ``csrf`` object. Restart *app.py* in your
+first terminal, then go back to the second browser tab and click the
+"Win $100!" button again. You will now see that the form is submitted
+successfully and your balance in the first application is decremented by $100.

examples/csrf/app.py

@@ -0,0 +1,40 @@
+from microdot import Microdot, redirect
+from microdot.cors import CORS
+from microdot.csrf import CSRF
+
+app = Microdot()
+cors = CORS(app, allowed_origins=['http://localhost:5000'])
+csrf = CSRF(app, cors)
+
+balance = 1000
+
+
+@app.route('/', methods=['GET', 'POST'])
+def index(request):
+    global balance
+    if request.method == 'POST':
+        try:
+            balance -= float(request.form['amount'])
+        except ValueError:
+            pass
+        return redirect('/')
+
+    page = f'''<!doctype html>
+<html>
+  <head>
+    <title>CSRF Example</title>
+  </head>
+  <body>
+    <h1>CSRF Example</h1>
+    <p>You have ${balance:.02f}</p>
+    <form method="POST" action="">
+      Pay $<input type="text" name="amount" size="10" />
+      <input type="submit" value="Issue Payment" />
+    </form>
+  </body>
+</html>'''
+    return page, {'Content-Type': 'text/html'}
+
+
+if __name__ == '__main__':
+    app.run(debug=True)

examples/csrf/evil.py

@@ -0,0 +1,25 @@
+from microdot import Microdot
+
+app = Microdot()
+
+
+@app.route('/', methods=['GET', 'POST'])
+def index(request):
+    page = '''<!doctype html>
+<html>
+  <head>
+    <title>CSRF Example</title>
+  </head>
+  <body>
+    <h1>Evil Site</h1>
+    <form method="POST" action="http://localhost:5000">
+      <input type="hidden" name="amount" value="100" />
+      <input type="submit" value="Win $100!" />
+    </form>
+  </body>
+</html>'''
+    return page, {'Content-Type': 'text/html'}
+
+
+if __name__ == '__main__':
+    app.run(port=5001, debug=True)

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "microdot"
-version = "2.4.0"
+version = "2.5.1"
 authors = [
     { name = "Miguel Grinberg", email = "miguel.grinberg@gmail.com" },
 ]
@@ -31,6 +31,7 @@ dev = [
 ]
 docs = [
     "sphinx",
+    "furo",
     "pyjwt",
 ]
 

src/microdot/__init__.py

@@ -1,4 +1,4 @@
 from microdot.microdot import Microdot, Request, Response, abort, redirect, \
     send_file, URLPattern, AsyncBytesIO, iscoroutine  # noqa: F401
 
-__version__ = '2.4.0'
+__version__ = '2.5.1'

src/microdot/asgi.py

@@ -48,15 +48,47 @@ class Microdot(BaseMicrodot):
     """A subclass of the core :class:`Microdot <microdot.Microdot>` class that
     implements the ASGI protocol.
 
+    :param startup: An optional function to handle the `lifespan.startup` ASGI
+                    signal.
+    :param shutdown: An optional function to handle the `lifespan.shutdown`
+                     ASGI signal.
+
     This class must be used as the application instance when running under an
     ASGI web server.
     """
-    def __init__(self):
+    def __init__(self, lifespan_startup=None, lifespan_shutdown=None):
         super().__init__()
+        self.lifespan_startup = lifespan_startup
+        self.lifespan_shutdown = lifespan_shutdown
         self.embedded_server = False
 
+    async def handle_lifespan(self, scope, receive, send):
+        while True:
+            message = await receive()
+            if message['type'] == 'lifespan.startup':
+                try:
+                    if self.lifespan_startup:
+                        await self.lifespan_startup(scope)
+                except Exception as e:
+                    await send({'type': 'lifespan.startup.failed',
+                                'message': repr(e)})
+                else:
+                    await send({'type': 'lifespan.startup.complete'})
+            elif message['type'] == 'lifespan.shutdown':  # pragma: no branch
+                try:
+                    if self.lifespan_shutdown:
+                        await self.lifespan_shutdown(scope)
+                except Exception as e:
+                    await send({'type': 'lifespan.shutdown.failed',
+                                'message': repr(e)})
+                else:
+                    await send({'type': 'lifespan.shutdown.complete'})
+                break
+
     async def asgi_app(self, scope, receive, send):
         """An ASGI application."""
+        if scope['type'] == 'lifespan':
+            return await self.handle_lifespan(scope, receive, send)
         if scope['type'] not in ['http', 'websocket']:  # pragma: no cover
             return
         path = scope['path']
@@ -91,7 +123,8 @@ class Microdot(BaseMicrodot):
             headers,
             body=body,
             stream=stream,
-            sock=(receive, send))
+            sock=(receive, send),
+            scheme=scope.get('scheme'))
         req.asgi_scope = scope
 
         res = await self.dispatch_request(req)

src/microdot/csrf.py

@@ -0,0 +1,120 @@
+from microdot import abort
+
+
+class CSRF:
+    """CSRF protection for Microdot routes.
+
+    :param app: The application instance.
+    :param cors: The ``CORS`` instance that defines the origins that are
+                 trusted by the application. This is used to validate requests
+                 from older browsers that do not send the ``Sec-Fetch-Site``
+                 header.
+    :param protect_all: If ``True``, all state changing routes are protected by
+                        default, with the exception of routes that are
+                        decorated with the :meth:`exempt <exempt>` decorator.
+                        If ``False``, only routes decorated with the
+                        :meth:`protect <protect>` decorator are protected. The
+                        default is ``True``.
+    :param allow_subdomains: If ``True``, requests from subdomains of the
+                             application domain are trusted. The default is
+                             ``False``.
+
+    CSRF protection is implemented by checking the ``Sec-Fetch-Site`` sent by
+    browsers. When the ``cors`` argument is provided, requests from older
+    browsers that do not support the ``Sec-Fetch-Site`` header are validated
+    by checking the ``Origin`` header.
+    """
+    SAFE_METHODS = ['GET', 'HEAD', 'OPTIONS']
+
+    def __init__(self, app=None, cors=None, protect_all=True,
+                 allow_subdomains=False):
+        self.cors = None
+        self.protect_all = protect_all
+        self.allow_subdomains = allow_subdomains
+        self.exempt_routes = []
+        self.protected_routes = []
+        if app is not None:
+            self.initialize(app, cors)
+
+    def initialize(self, app, cors=None):
+        """Initialize the CSRF class.
+
+        :param app: The application instance.
+        :param cors: The ``CORS`` instance that defines the origins that are
+                     trusted by the application. This is used to validate
+                     requests from older browsers that do not send the
+                     ``Sec-Fetch-Site`` header.
+        """
+        self.cors = cors
+
+        @app.before_request
+        async def csrf_before_request(request):
+            if (
+                self.protect_all
+                and request.method not in self.SAFE_METHODS
+                and request.route not in self.exempt_routes
+            ) or request.route in self.protected_routes:
+                allow = False
+                sfs = request.headers.get('Sec-Fetch-Site')
+                origin = request.headers.get('Origin')
+                if sfs:
+                    # if the Sec-Fetch-Site header was given, ensure it is not
+                    # cross-site
+                    if sfs in ['same-origin', 'none']:
+                        allow = True
+                    elif sfs == 'same-site' and self.allow_subdomains:
+                        allow = True
+                if not allow and origin and self.cors and \
+                        self.cors.allowed_origins != '*':
+                    # if we have a list of allowed origins, then we can
+                    # validate the origin
+                    if not self.allow_subdomains:
+                        allow = origin in self.cors.allowed_origins
+                    else:
+                        origin_scheme, origin_host = origin.split('://', 1)
+                        for allowed_origin in self.cors.allowed_origins:
+                            allowed_scheme, allowed_host = \
+                                allowed_origin.split('://', 1)
+                            if origin == allowed_origin or (
+                                origin_host.endswith('.' + allowed_host)
+                                and origin_scheme == allowed_scheme
+                            ):
+                                allow = True
+                                break
+                if not allow and not sfs and not origin:
+                    allow = True  # no headers to check
+
+                if not allow:
+                    abort(403, 'Forbidden')
+
+    def exempt(self, f):
+        """Decorator to exempt a route from CSRF protection.
+
+        This decorator must be added immediately after the route decorator to
+        disable CSRF protection on the route. Example::
+
+            @app.post('/submit')
+            @csrf.exempt
+            # add additional decorators here
+            def submit(request):
+                # ...
+        """
+        self.exempt_routes.append(f)
+        return f
+
+    def protect(self, f):
+        """Decorator to protect a route against CSRF attacks.
+
+        This is useful when it is necessary to protect a request that uses one
+        of the safe methods that are not supposed to make state changes. The
+        decorator must be added immediately after the route decorator to
+        disable CSRF protection on the route. Example::
+
+            @app.get('/data')
+            @csrf.force
+            # add additional decorators here
+            def get_data(request):
+                # ...
+        """
+        self.protected_routes.append(f)
+        return f

src/microdot/login.py

@@ -82,6 +82,7 @@ class Login:
         session['_user_id'] = user.id
         session['_fresh'] = True
         session.save()
+        request.g.current_user = user
 
         if remember:
             days = 30 if remember is True else int(remember)
@@ -104,9 +105,21 @@ class Login:
         session.pop('_user_id', None)
         session.pop('_fresh', None)
         session.save()
+        request.g.current_user = None
         if '_remember' in request.cookies:
             self._update_remember_cookie(request, 0)
 
+    async def get_current_user(self, request):
+        """Return the currently logged in user."""
+        if not hasattr(request.g, 'current_user'):
+            user_id = self._get_user_id_from_session(request)
+            if user_id:
+                request.g.current_user = await invoke_handler(
+                    self.user_loader_callback, user_id)
+            else:
+                request.g.current_user = None
+        return request.g.current_user
+
     def __call__(self, f):
         """Decorator to protect a route with authentication.
 
@@ -124,12 +137,8 @@ class Login:
 
         """
         async def wrapper(request, *args, **kwargs):
-            user_id = self._get_user_id_from_session(request)
-            if not user_id:
-                return await self._redirect_to_login(request)
-            request.g.current_user = await invoke_handler(
-                self.user_loader_callback, user_id)
-            if not request.g.current_user:
+            user = await self.get_current_user(request)
+            if not user:
                 return await self._redirect_to_login(request)
             return await invoke_handler(f, request, *args, **kwargs)
 

src/microdot/microdot.py

@@ -321,14 +321,17 @@ class Request:
 
     def __init__(self, app, client_addr, method, url, http_version, headers,
                  body=None, stream=None, sock=None, url_prefix='',
-                 subapp=None):
+                 subapp=None, scheme=None, route=None):
         #: The application instance to which this request belongs.
         self.app = app
         #: The address of the client, as a tuple (host, port).
         self.client_addr = client_addr
         #: The HTTP method of the request.
         self.method = method
-        #: The request URL, including the path and query string.
+        #: The scheme of the request, either `http` or `https`.
+        self.scheme = scheme or 'http'
+        #: The request URL, including the path and query string, but not the
+        #: scheme or the host, which is available in the ``Host`` header.
         self.url = url
         #: The URL prefix, if the endpoint comes from a mounted
         #: sub-application, or else ''.
@@ -336,6 +339,8 @@ class Request:
         #: The sub-application instance, or `None` if this isn't a mounted
         #: endpoint.
         self.subapp = subapp
+        #: The route function that handles this request.
+        self.route = route
         #: The path portion of the URL.
         self.path = url
         #: The query string portion of the URL.
@@ -379,7 +384,8 @@ class Request:
         self.after_request_handlers = []
 
     @staticmethod
-    async def create(app, client_reader, client_writer, client_addr):
+    async def create(app, client_reader, client_writer, client_addr,
+                     scheme=None):
         """Create a request object.
 
         :param app: The Microdot application instance.
@@ -388,6 +394,7 @@ class Request:
         :param client_writer: An output stream where the response data can be
                               written.
         :param client_addr: The address of the client, as a tuple.
+        :param scheme: The scheme of the request, either 'http' or 'https'.
 
         This method is a coroutine. It returns a newly created ``Request``
         object.
@@ -424,7 +431,7 @@ class Request:
 
         return Request(app, client_addr, method, url, http_version, headers,
                        body=body, stream=stream,
-                       sock=(client_reader, client_writer))
+                       sock=(client_reader, client_writer), scheme=scheme)
 
     def _parse_urlencoded(self, urlencoded):
         data = MultiDict()
@@ -767,7 +774,7 @@ class Response:
 
         :param filename: The filename of the file.
         :param status_code: The 3xx status code to use for the redirect. The
-                            default is 302.
+                            default is 200.
         :param content_type: The ``Content-Type`` header to use in the
                              response. If omitted, it is generated
                              automatically from the file extension of the
@@ -949,6 +956,7 @@ class Microdot:
         self.after_error_request_handlers = []
         self.error_handlers = {}
         self.options_handler = self.default_options_handler
+        self.ssl = False
         self.debug = False
         self.server = None
 
@@ -1242,6 +1250,7 @@ class Microdot:
 
             asyncio.run(main())
         """
+        self.ssl = ssl
         self.debug = debug
 
         async def serve(reader, writer):
@@ -1422,6 +1431,8 @@ class Microdot:
                 try:
                     res = None
                     if callable(f):
+                        req.route = f
+
                         # invoke the before request handlers
                         for handler in self.get_request_handlers(
                                 req, 'before_request', False):

src/microdot/session.py

@@ -23,7 +23,8 @@ class SessionDict(dict):
 
 
 class Session:
-    """
+    """Session handling
+
     :param app: The application instance.
     :param secret_key: The secret key, as a string or bytes object.
     :param cookie_options: A dictionary with cookie options to pass as

src/microdot/test_client.py

@@ -117,6 +117,8 @@ class TestClient:
     :param app: The Microdot application instance.
     :param cookies: A dictionary of cookies to use when sending requests to the
                     application.
+    :param scheme: The scheme to use for requests, either 'http' or 'https'.
+    :param host: The host to use for requests.
 
     The following example shows how to create a test client for an application
     and send a test request::
@@ -137,9 +139,11 @@ class TestClient:
     """
     __test__ = False  # remove this class from pytest's test collection
 
-    def __init__(self, app, cookies=None):
+    def __init__(self, app, cookies=None, scheme=None, host=None):
         self.app = app
         self.cookies = cookies or {}
+        self.scheme = scheme
+        self.host = host or 'example.com:1234'
 
     def _process_body(self, body, headers):
         if body is None:
@@ -152,8 +156,6 @@ class TestClient:
             body = body.encode()
         if body and 'Content-Length' not in headers:
             headers['Content-Length'] = str(len(body))
-        if 'Host' not in headers:  # pragma: no branch
-            headers['Host'] = 'example.com:1234'
         return body, headers
 
     def _process_cookies(self, path, headers):
@@ -176,6 +178,8 @@ class TestClient:
     def _render_request(self, method, path, headers, body):
         request_bytes = '{method} {path} HTTP/1.0\n'.format(
             method=method, path=path)
+        if 'Host' not in headers:  # pragma: no branch
+            request_bytes += 'Host: {host}\n'.format(host=self.host)
         for header, value in headers.items():
             request_bytes += '{header}: {value}\n'.format(
                 header=header, value=value)
@@ -236,7 +240,7 @@ class TestClient:
             writer = AsyncBytesIO(b'')
 
         req = await Request.create(self.app, reader, writer,
-                                   ('127.0.0.1', 1234))
+                                   ('127.0.0.1', 1234), scheme=self.scheme)
         res = await self.app.dispatch_request(req)
         if res == Response.already_handled:
             return TestResponse()

src/microdot/wsgi.py

@@ -96,7 +96,8 @@ class Microdot(BaseMicrodot):
             headers,
             body=body,
             stream=stream,
-            sock=sock)
+            sock=sock,
+            scheme=environ.get('wsgi.url_scheme'))
         req.environ = environ
 
         res = self.loop.run_until_complete(self.dispatch_request(req))

tests/__init__.py

@@ -12,3 +12,4 @@ from tests.test_utemplate import *  # noqa: F401, F403
 from tests.test_session import *  # noqa: F401, F403
 from tests.test_auth import *  # noqa: F401, F403
 from tests.test_login import *  # noqa: F401, F403
+from tests.test_csrf import *  # noqa: F401, F403

tests/test_asgi.py

@@ -170,3 +170,103 @@ class TestASGI(unittest.TestCase):
             self._run(app(scope, receive, send))
 
         kill.assert_called()
+
+    def test_no_lifespan(self):
+        app = Microdot()
+
+        scope = {
+            'type': 'lifespan',
+            'asgi': {'version': '3.0'},
+            'state': {},
+        }
+
+        messages = [
+            {'type': 'lifespan.startup'},
+            {'type': 'lifespan.shutdown'},
+        ]
+        message_iter = iter(messages)
+        sends = []
+
+        async def receive():
+            return next(message_iter)
+
+        async def send(packet):
+            sends.append(packet)
+
+        self._run(app(scope, receive, send))
+        self.assertEqual(sends, [
+            {'type': 'lifespan.startup.complete'},
+            {'type': 'lifespan.shutdown.complete'},
+        ])
+
+    def test_lifespan(self):
+        async def startup(scope):
+            scope['state']['foo'] = 'bar'
+
+        async def shutdown(scope):
+            self.assertEqual(scope['state']['foo'], 'bar')
+            scope['state']['foo'] = 'baz'
+
+        app = Microdot(lifespan_startup=startup, lifespan_shutdown=shutdown)
+
+        scope = {
+            'type': 'lifespan',
+            'asgi': {'version': '3.0'},
+            'state': {},
+        }
+
+        messages = [
+            {'type': 'lifespan.startup'},
+            {'type': 'lifespan.shutdown'},
+        ]
+        message_iter = iter(messages)
+        sends = []
+
+        async def receive():
+            return next(message_iter)
+
+        async def send(packet):
+            sends.append(packet)
+
+        self._run(app(scope, receive, send))
+        self.assertEqual(scope['state']['foo'], 'baz')
+        self.assertEqual(sends, [
+            {'type': 'lifespan.startup.complete'},
+            {'type': 'lifespan.shutdown.complete'},
+        ])
+
+    def test_lifespan_errors(self):
+        async def startup(scope):
+            return scope['scope']['foo']  # KeyError
+
+        async def shutdown(scope):
+            return 1 / 0
+
+        app = Microdot(lifespan_startup=startup, lifespan_shutdown=shutdown)
+
+        scope = {
+            'type': 'lifespan',
+            'asgi': {'version': '3.0'},
+            'state': {},
+        }
+
+        messages = [
+            {'type': 'lifespan.startup'},
+            {'type': 'lifespan.shutdown'},
+        ]
+        message_iter = iter(messages)
+        sends = []
+
+        async def receive():
+            return next(message_iter)
+
+        async def send(packet):
+            sends.append(packet)
+
+        self._run(app(scope, receive, send))
+        self.assertEqual(sends, [
+            {'type': 'lifespan.startup.failed',
+             'message': "KeyError('scope')"},
+            {'type': 'lifespan.shutdown.failed',
+             'message': "ZeroDivisionError('division by zero')"},
+        ])

tests/test_csrf.py

@@ -0,0 +1,310 @@
+import asyncio
+import unittest
+from microdot import Microdot
+from microdot.cors import CORS
+from microdot.csrf import CSRF
+from microdot.test_client import TestClient
+
+
+class TestCSRF(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        if hasattr(asyncio, 'set_event_loop'):
+            asyncio.set_event_loop(asyncio.new_event_loop())
+        cls.loop = asyncio.get_event_loop()
+
+    def _run(self, coro):
+        return self.loop.run_until_complete(coro)
+
+    def test_protect_all_true(self):
+        app = Microdot()
+        csrf = CSRF(app)
+
+        @app.get('/')
+        def index(request):
+            return 204
+
+        @app.post('/submit')
+        def submit(request):
+            return 204
+
+        @app.post('/submit-exempt')
+        @csrf.exempt
+        def submit_exempt(request):
+            return 204
+
+        @app.get('/get-protected')
+        @csrf.protect
+        def get_protected(request):
+            return 204
+
+        client = TestClient(app)
+
+        res = self._run(client.get('/'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'https://evil.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+        res = self._run(client.post('/submit'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'same-site'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'same-origin'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+        res = self._run(client.post('/submit-exempt'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit-exempt', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get('/get-protected'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/get-protected', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 403)
+
+    def test_protect_all_false(self):
+        app = Microdot()
+        csrf = CSRF(protect_all=False)
+        csrf.initialize(app)
+
+        @app.get('/')
+        def index(request):
+            return 204
+
+        @app.post('/submit')
+        @csrf.protect
+        def submit(request):
+            return 204
+
+        @app.post('/submit-exempt')
+        def submit_exempt(request):
+            return 204
+
+        client = TestClient(app)
+
+        res = self._run(client.get('/'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'https://evil.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+        res = self._run(client.post('/submit'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'same-site'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'same-origin'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+        res = self._run(client.post('/submit-exempt'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit-exempt', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+    def test_allow_subdomains(self):
+        app = Microdot()
+        csrf = CSRF(allow_subdomains=True)
+        csrf.initialize(app)
+
+        @app.get('/')
+        def index(request):
+            return 204
+
+        @app.post('/submit')
+        def submit(request):
+            return 204
+
+        @app.post('/submit-exempt')
+        @csrf.exempt
+        def submit_exempt(request):
+            return 204
+
+        client = TestClient(app)
+
+        res = self._run(client.get('/'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'https://evil.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+        res = self._run(client.post('/submit'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'same-site'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Sec-Fetch-Site': 'same-origin'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+        res = self._run(client.post('/submit-exempt'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit-exempt', headers={'Sec-Fetch-Site': 'cross-site'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+    def test_allowed_origins(self):
+        app = Microdot()
+        cors = CORS(allowed_origins=['http://foo.com', 'https://bar.com:8888'])
+        csrf = CSRF()
+        csrf.initialize(app, cors)
+
+        @app.get('/')
+        def index(request):
+            return 204
+
+        @app.post('/submit')
+        def submit(request):
+            return 204
+
+        client = TestClient(app)
+
+        res = self._run(client.get('/'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'http://foo.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'https://baz.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'http://x.baz.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+        res = self._run(client.post('/submit'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'https://bar.com:8888'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'http://bar.com:8888'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={
+                'Sec-Fetch-Site': 'cross-site',
+                'Origin': 'https://bar.com:8888',
+            },
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={
+                'Sec-Fetch-Site': 'cross-site',
+                'Origin': 'https://bar.com:8889',
+            },
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={
+                'Sec-Fetch-Site': 'cross-site',
+            },
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'https://x.y.bar.com:8888'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'http://baz.com'}
+        ))
+        self.assertEqual(res.status_code, 403)
+
+    def test_allowed_origins_with_subdomains(self):
+        app = Microdot()
+        cors = CORS(allowed_origins=['http://foo.com', 'https://bar.com:8888'])
+        csrf = CSRF(allow_subdomains=True)
+        csrf.initialize(app, cors)
+
+        @app.get('/')
+        def index(request):
+            return 204
+
+        @app.post('/submit')
+        def submit(request):
+            return 204
+
+        client = TestClient(app)
+
+        res = self._run(client.get('/'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'http://foo.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'https://baz.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.get(
+            '/', headers={'Origin': 'http://x.baz.com'}
+        ))
+        self.assertEqual(res.status_code, 204)
+
+        res = self._run(client.post('/submit'))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'https://bar.com:8888'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'http://bar.com:8888'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'https://x.y.bar.com:8888'}
+        ))
+        self.assertEqual(res.status_code, 204)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'http://x.y.bar.com:8888'}
+        ))
+        self.assertEqual(res.status_code, 403)
+        res = self._run(client.post(
+            '/submit', headers={'Origin': 'http://baz.com'}
+        ))
+        self.assertEqual(res.status_code, 403)

tests/test_login.py

@@ -32,7 +32,9 @@ class TestLogin(unittest.TestCase):
 
         @app.get('/')
         @login
-        def index(request):
+        async def index(request):
+            assert await login.get_current_user(request) == \
+                request.g.current_user
             return request.g.current_user.name
 
         @app.post('/login')

tests/test_microdot.py

@@ -180,6 +180,30 @@ class TestMicrodot(unittest.TestCase):
                              'text/plain; charset=UTF-8')
             self.assertEqual(res.text, method)
 
+    def test_http_host(self):
+        app = Microdot()
+
+        @app.route('/')
+        def index(req):
+            return req.scheme + "://" + req.headers['Host']
+
+        client = TestClient(app, host='foo.com')
+        res = self._run(client.get('/'))
+        self.assertEqual(res.status_code, 200)
+        self.assertEqual(res.text, 'http://foo.com')
+
+    def test_https_host(self):
+        app = Microdot()
+
+        @app.route('/')
+        def index(req):
+            return req.scheme + "://" + req.headers['Host']
+
+        client = TestClient(app, scheme='https', host='foo.com')
+        res = self._run(client.get('/'))
+        self.assertEqual(res.status_code, 200)
+        self.assertEqual(res.text, 'https://foo.com')
+
     def test_headers(self):
         app = Microdot()
 

tox.ini

@@ -17,7 +17,7 @@ python =
 [testenv]
 commands=
     pip install -e .
-    pytest -p no:logging --cov=src --cov-config=.coveragerc --cov-branch --cov-report=term-missing --cov-report=xml tests
+    pytest -p no:logging --cov=src --cov-config=.coveragerc --cov-branch --cov-report=term-missing --cov-report=xml {posargs}
 deps=
     pytest
     pytest-cov
@@ -64,6 +64,7 @@ commands=
 changedir=docs
 deps=
     sphinx
+    furo
     pyjwt
 allowlist_externals=
     make