Ticket #2906: request_response.diff

docs/request_response.txt

@@ -432 +432 @@
 
 ``HttpResponseServerError``
     Acts just like ``HttpResponse`` but uses a 500 status code.
+
+Returning Errors
+================
+
+Returning error codes in Django is easy, as you saw some lines above there
+are the ``HttpResponseNotFound``, ``HttpResponseForbidden``,
+``HttpResponseServerError``, etc. subclasses which, when returned by a view,
+will make the Web server return the corresponding error codes (404, 403, 500,
+...) 
+
+But there are more things you can do when returning erros, like calling a
+personalized view, returning a custom template, ...
+
+The Http404 exception
+---------------------
+There is an exception in Django that you can raise in your views, it's does
+the same thing as returning a ``HttpResponseNotFound``, but from the world of
+exceptions.
+
+    from django.http import Http404
+    # ...
+    def detail(request, poll_id):
+        try:
+            p = Poll.objects.get(pk=poll_id)
+        except Poll.DoesNotExist:
+            raise Http404
+        return render_to_response('polls/detail.html', {'poll': p})
+
+Error views
+~~~~~~~~~~~
+
+The 404 (page not found) view
+-----------------------------
+
+When you raise ``Http404`` from within a view, Django will load a special view
+devoted to handling 404 errors. It finds it by looking for the variable
+``handler404``, which is a string in Python dotted syntax -- the same format
+the normal URLconf callbacks use. A 404 view itself has nothing special: It's
+just a normal view.
+
+You normally won't have to bother with writing 404 views. By default, URLconfs
+have the following line up top::
+
+    from django.conf.urls.defaults import *
+
+That takes care of setting ``handler404`` in the current module. As you can see
+in ``django/conf/urls/defaults.py``, ``handler404`` is set to
+``'django.views.defaults.page_not_found'`` by default.
+
+Three more things to note about 404 views:
+
+    * The 404 view is also called if Django doesn't find a match after checking
+      every regular expression in the URLconf.
+    * If you don't define your own 404 view -- and simply use the default,
+      which is recommended -- you still have one obligation: To create a
+      ``404.html`` template in the root of your template directory. The default
+      404 view will use that template for all 404 errors.
+    * If ``DEBUG`` is set to ``True`` (in your settings module) then your 404
+      view will never be used, and the traceback will be displayed instead.
+
+The 500 (server error) view
+---------------------------
+
+Similarly, URLconfs may define a ``handler500``, which points to a view to call
+in case of server errors. Server errors happen when you have runtime errors in
+view code.