error handlers

examples/gpio.html

@@ -15,9 +15,12 @@
             }
             function onLoad() {
                 showMessage();
-                var form = getCookie('form').split(',')
-                document.getElementById('pin').selectedIndex = parseInt(form[0]);
-                document.getElementById(form[1]).checked = true;
+                var form = getCookie('form');
+                if (form) {
+                    form = form.split(',')
+                    document.getElementById('pin').selectedIndex = parseInt(form[0]);
+                    document.getElementById(form[1]).checked = true;
+                }
             }
         </script>
     </head>

microdot.py

@@ -243,6 +243,7 @@ class URLPattern():
 class Microdot():
     def __init__(self) :
         self.url_map = []
+        self.error_handlers = {}
 
     def route(self, url_pattern, methods=None):
         def decorated(f):
@@ -251,6 +252,12 @@ class Microdot():
             return f
         return decorated
 
+    def errorhandler(self, status_code_or_exception_class):
+        def decorated(f):
+            self.error_handlers[status_code_or_exception_class] = f
+            return f
+        return decorated
+
     def run(self, host='0.0.0.0', port=5000):
         s = socket.socket()
         ai = socket.getaddrinfo(host, port)
@@ -271,14 +278,28 @@ class Microdot():
                     if args is not None:
                         f = route_handler
                         break
-            if f:
-                resp = f(req, **args)
-                if isinstance(resp, tuple):
-                    resp = Response(*resp)
-                elif not isinstance(resp, Response):
-                    resp = Response(resp)
-                resp.write(req.client_stream)
-                req.close()
+            try:
+                if f:
+                    resp = f(req, **args)
+                elif 404 in self.error_handlers:
+                    resp = self.error_handlers[404](req)
+                else:
+                    resp = 'Not found', 404
+            except Exception as exc:
+                resp = None
+                if exc.__class__ in self.error_handlers:
+                    try:
+                        resp = self.error_handlers[exc.__class__](req, exc)
+                    except:
+                        pass
+                if resp is None:
+                    resp = 'Internal server error', 500
+            if isinstance(resp, tuple):
+                resp = Response(*resp)
+            elif not isinstance(resp, Response):
+                resp = Response(resp)
+            resp.write(req.client_stream)
+            req.close()
 
 
 redirect = Response.redirect