===============
View decorators
===============

.. module:: django.views.decorators.http

Django provides several decorators that can be applied to views to support
various HTTP features.

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)

This decorator is used to ensure 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 accept the GET method.

.. function:: require_POST()

Decorator to require that a view only accept the POST method.

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>`.