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Fixed #2906 -- Added documentation about HTTP error code returns and the

default 404 and 500 code error handlers. Based on a patch from Marc Fargas.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@4534 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick 2007-02-17 04:59:49 +00:00
parent 892202b319
commit 369d9ffa3d

View File

@ -432,3 +432,77 @@ types of HTTP responses. Like ``HttpResponse``, these subclasses live in
``HttpResponseServerError``
Acts just like ``HttpResponse`` but uses a 500 status code.
Returning Errors
================
Returning HTTP error codes in Django is easy; there are the
``HttpResponseNotFound``, ``HttpResponseForbidden``,
``HttpResponseServerError``, etc. subclasses mentioned above which, when
returned by a view, will make the Web server return the corresponding error
codes (404, 403, 500, ...) and HTTP headers.
The Http404 exception
---------------------
When you return an error such as ``HttpResponseNotFound``, you are responsible
for returning the error page and everything yourself. Since this extra
information will normally be fairly uniform across your site and because you
often want to bail out of the middle of a view with a quick "content not
found" error, Django provides the ``Http404`` exception. This exception is
caught by Django and results in the standard error page for your application
being returned along with a 404 error code (although this behavior can be
customised, as described below).
Using this exception in your code would look something like::
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})
In order to use the ``Http404`` exception to its fullest, you should create a
template that is displayed when a 404 error is raised. This template should be
called ``404.html`` and located in the top level of your template tree.
Customing error views
---------------------
The 404 (page not found) view
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When you raise the ``Http404`` exception, 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
contain the following line::
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 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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
URLconfs may also 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.