pytask.new: parts/django/docs/topics/http/views.txt@c63a9519dc37 (annotated)

69 c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	1	=============
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	2	Writing Views
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	3	=============
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	4
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	5	A view function, or view for short, is simply a Python function that takes a
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	6	Web request and returns a Web response. This response can be the HTML contents
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	7	of a Web page, or a redirect, or a 404 error, or an XML document, or an image .
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	8	. . or anything, really. The view itself contains whatever arbitrary logic is
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	9	necessary to return that response. This code can live anywhere you want, as long
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	10	as it's on your Python path. There's no other requirement--no "magic," so to
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	11	speak. For the sake of putting the code somewhere, let's create a file called
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	12	``views.py`` in the ``mysite`` directory, which you created in the previous
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	13	chapter.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	14
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	15	A simple view
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	16	=============
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	17
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	18	Here's a view that returns the current date and time, as an HTML document:
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	19
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	20	.. code-block:: python
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	21
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	22	from django.http import HttpResponse
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	23	import datetime
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	24
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	25	def current_datetime(request):
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	26	now = datetime.datetime.now()
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	27	html = "<html><body>It is now %s.</body></html>" % now
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	28	return HttpResponse(html)
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	29
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	30	Let's step through this code one line at a time:
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	31
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	32	* First, we import the class :class:`~django.http.HttpResponse` from the
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	33	:mod:`django.http` module, along with Python's ``datetime`` library.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	34
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	35	* Next, we define a function called ``current_datetime``. This is the view
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	36	function. Each view function takes an :class:`~django.http.HttpRequest`
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	37	object as its first parameter, which is typically named ``request``.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	38
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	39	Note that the name of the view function doesn't matter; it doesn't have to
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	40	be named in a certain way in order for Django to recognize it. We're
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	41	calling it ``current_datetime`` here, because that name clearly indicates
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	42	what it does.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	43
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	44	* The view returns an :class:`~django.http.HttpResponse` object that
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	45	contains the generated response. Each view function is responsible for
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	46	returning an :class:`~django.http.HttpResponse` object. (There are
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	47	exceptions, but we'll get to those later.)
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	48
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	49	.. admonition:: Django's Time Zone
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	50
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	51	Django includes a ``TIME_ZONE`` setting that defaults to
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	52	``America/Chicago``. This probably isn't where you live, so you might want
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	53	to change it in your settings file.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	54
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	55	Mapping URLs to Views
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	56	=====================
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	57
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	58	So, to recap, this view function returns an HTML page that includes the current
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	59	date and time. To display this view at a particular URL, you'll need to create a
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	60	URLconf; see :doc:`/topics/http/urls` for instructions.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	61
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	62	Returning errors
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	63	================
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	64
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	65	Returning HTTP error codes in Django is easy. There are subclasses of
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	66	:class:`~django.http.HttpResponse` for a number of common HTTP status codes
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	67	other than 200 (which means "OK"). You can find the full list of available
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	68	subclasses in the :ref:`request/response <ref-httpresponse-subclasses>`
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	69	documentation. Just return an instance of one of those subclasses instead of
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	70	a normal :class:`~django.http.HttpResponse` in order to signify an error. For
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	71	example::
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	72
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	73	def my_view(request):
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	74	# ...
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	75	if foo:
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	76	return HttpResponseNotFound('<h1>Page not found</h1>')
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	77	else:
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	78	return HttpResponse('<h1>Page was found</h1>')
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	79
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	80	There isn't a specialized subclass for every possible HTTP response code,
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	81	since many of them aren't going to be that common. However, as documented in
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	82	the :class:`~django.http.HttpResponse` documentation, you can also pass the
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	83	HTTP status code into the constructor for :class:`~django.http.HttpResponse`
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	84	to create a return class for any status code you like. For example::
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	85
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	86	def my_view(request):
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	87	# ...
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	88
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	89	# Return a "created" (201) response code.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	90	return HttpResponse(status=201)
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	91
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	92	Because 404 errors are by far the most common HTTP error, there's an easier way
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	93	to handle those errors.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	94
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	95	The Http404 exception
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	96	---------------------
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	97
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	98	.. class:: django.http.Http404()
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	99
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	100	When you return an error such as :class:`~django.http.HttpResponseNotFound`,
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	101	you're responsible for defining the HTML of the resulting error page::
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	102
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	103	return HttpResponseNotFound('<h1>Page not found</h1>')
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	104
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	105	For convenience, and because it's a good idea to have a consistent 404 error page
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	106	across your site, Django provides an ``Http404`` exception. If you raise
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	107	``Http404`` at any point in a view function, Django will catch it and return the
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	108	standard error page for your application, along with an HTTP error code 404.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	109
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	110	Example usage::
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	111
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	112	from django.http import Http404
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	113
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	114	def detail(request, poll_id):
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	115	try:
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	116	p = Poll.objects.get(pk=poll_id)
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	117	except Poll.DoesNotExist:
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	118	raise Http404
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	119	return render_to_response('polls/detail.html', {'poll': p})
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	120
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	121	In order to use the ``Http404`` exception to its fullest, you should create a
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	122	template that is displayed when a 404 error is raised. This template should be
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	123	called ``404.html`` and located in the top level of your template tree.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	124
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	125	Customizing error views
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	126	=======================
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	127
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	128	The 404 (page not found) view
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	129	-----------------------------
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	130
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	131	When you raise an ``Http404`` exception, Django loads a special view devoted
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	132	to handling 404 errors. By default, it's the view
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	133	``django.views.defaults.page_not_found``, which loads and renders the template
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	134	``404.html``.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	135
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	136	This means you need to define a ``404.html`` template in your root template
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	137	directory. This template will be used for all 404 errors.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	138
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	139	This ``page_not_found`` view should suffice for 99% of Web applications, but if
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	140	you want to override the 404 view, you can specify ``handler404`` in your
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	141	URLconf, like so::
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	142
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	143	handler404 = 'mysite.views.my_custom_404_view'
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	144
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	145	Behind the scenes, Django determines the 404 view by looking for ``handler404``.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	146	By default, URLconfs contain the following line::
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	147
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	148	from django.conf.urls.defaults import *
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	149
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	150	That takes care of setting ``handler404`` in the current module. As you can see
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	151	in ``django/conf/urls/defaults.py``, ``handler404`` is set to
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	152	``'django.views.defaults.page_not_found'`` by default.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	153
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	154	Three things to note about 404 views:
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	155
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	156	* The 404 view is also called if Django doesn't find a match after checking
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	157	every regular expression in the URLconf.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	158
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	159	* If you don't define your own 404 view -- and simply use the
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	160	default, which is recommended -- you still have one obligation:
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	161	you must create a ``404.html`` template in the root of your
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	162	template directory. The default 404 view will use that template
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	163	for all 404 errors. The default 404 view will pass one variable
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	164	to the template: ``request_path``, which is the URL that resulted
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	165	in the 404.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	166
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	167	* The 404 view is passed a :class:`~django.template.RequestContext` and
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	168	will have access to variables supplied by your
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	169	:setting:`TEMPLATE_CONTEXT_PROCESSORS` setting (e.g.,
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	170	:setting:`MEDIA_URL`).
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	171
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	172	* If :setting:`DEBUG` is set to ``True`` (in your settings module), then
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	173	your 404 view will never be used, and the traceback will be displayed
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	174	instead.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	175
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	176	The 500 (server error) view
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	177	----------------------------
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	178
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	179	Similarly, Django executes special-case behavior in the case of runtime errors
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	180	in view code. If a view results in an exception, Django will, by default, call
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	181	the view ``django.views.defaults.server_error``, which loads and renders the
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	182	template ``500.html``.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	183
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	184	This means you need to define a ``500.html`` template in your root template
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	185	directory. This template will be used for all server errors. The default 500
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	186	view passes no variables to this template and is rendered with an empty
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	187	``Context`` to lessen the chance of additional errors.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	188
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	189	This ``server_error`` view should suffice for 99% of Web applications, but if
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	190	you want to override the view, you can specify ``handler500`` in your
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	191	URLconf, like so::
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	192
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	193	handler500 = 'mysite.views.my_custom_error_view'
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	194
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	195	Behind the scenes, Django determines the error view by looking for ``handler500``.
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	196	By default, URLconfs contain the following line::
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	197
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	198	from django.conf.urls.defaults import *
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	199
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	200	That takes care of setting ``handler500`` in the current module. As you can see
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	201	in ``django/conf/urls/defaults.py``, ``handler500`` is set to
c6bca38c1cbf Added buildout stuff and made changes accordingly Nishanth Amuluru <nishanth@fossee.in> parents: diff changeset	202	``'django.views.defaults.server_error'`` by default.

author	Nishanth Amuluru <nishanth@fossee.in>
	Sat, 08 Jan 2011 14:41:09 +0530
changeset 77	c63a9519dc37
parent 69	c6bca38c1cbf
permissions	-rw-r--r--