django/docs/topics/http/decorators.txt

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===============
View decorators
===============
.. module:: django.views.decorators.http
Django provides several decorators that can be applied to views to support
various HTTP features.
See :ref:`decorating-class-based-views` for how to use these decorators with
class-based views.
Allowed HTTP methods
====================
The decorators in :mod:`django.views.decorators.http` can be used to restrict
access to views based on the request method. These decorators will return
a :class:`django.http.HttpResponseNotAllowed` if the conditions are not met.
.. function:: require_http_methods(request_method_list)
Decorator to require that a view only accepts particular request
methods. Usage::
from django.views.decorators.http import require_http_methods
@require_http_methods(["GET", "POST"])
def my_view(request):
# I can assume now that only GET or POST requests make it this far
# ...
pass
Note that request methods should be in uppercase.
.. function:: require_GET()
Decorator to require that a view only accepts the GET method.
.. function:: require_POST()
Decorator to require that a view only accepts the POST method.
.. function:: require_safe()
Decorator to require that a view only accepts the GET and HEAD methods.
These methods are commonly considered "safe" because they should not have
the significance of taking an action other than retrieving the requested
resource.
.. note::
Web servers should automatically strip the content of responses to HEAD
requests while leaving the headers unchanged, so you may handle HEAD
requests exactly like GET requests in your views. Since some software,
such as link checkers, rely on HEAD requests, you might prefer
using ``require_safe`` instead of ``require_GET``.
Conditional view processing
===========================
The following decorators in :mod:`django.views.decorators.http` can be used to
control caching behavior on particular views.
.. function:: condition(etag_func=None, last_modified_func=None)
.. function:: etag(etag_func)
.. function:: last_modified(last_modified_func)
These decorators can be used to generate ``ETag`` and ``Last-Modified``
headers; see
:doc:`conditional view processing </topics/conditional-view-processing>`.
.. module:: django.views.decorators.gzip
GZip compression
================
The decorators in :mod:`django.views.decorators.gzip` control content
compression on a per-view basis.
.. function:: gzip_page()
This decorator compresses content if the browser allows gzip compression.
It sets the ``Vary`` header accordingly, so that caches will base their
storage on the ``Accept-Encoding`` header.
.. module:: django.views.decorators.vary
Vary headers
============
The decorators in :mod:`django.views.decorators.vary` can be used to control
caching based on specific request headers.
.. function:: vary_on_cookie(func)
.. function:: vary_on_headers(*headers)
The ``Vary`` header defines which request headers a cache mechanism should take
into account when building its cache key.
See :ref:`using vary headers <using-vary-headers>`.
.. module:: django.views.decorators.cache
Caching
=======
The decorators in :mod:`django.views.decorators.cache` control server and
client-side caching.
.. function:: cache_control(**kwargs)
This decorator patches the response's ``Cache-Control`` header by adding
all of the keyword arguments to it. See
:func:`~django.utils.cache.patch_cache_control` for the details of the
transformation.
.. function:: never_cache(view_func)
This decorator adds a ``Cache-Control: max-age=0, no-cache, no-store,
must-revalidate, private`` header to a response to indicate that a page
should never be cached.
.. versionchanged:: 3.0
``private`` directive was added.