Fixed #15906 - Documented HEAD method in CBVs; thanks zsiciarz for the patch.

        delegated to :meth:`~View.get()`, a ``POST`` to :meth:`~View.post()`,

        and so on.

        By default, a ``HEAD`` request will be delegated to :meth:`~View.get()`.

        If you need to handle ``HEAD`` requests in a different way than ``GET``,

        you can override the :meth:`~View.head()` method. See

        :ref:`supporting-other-http-methods` for an example.

        The default implementation also sets ``request``, ``args`` and

        ``kwargs`` as instance variables, so any method on the view can know

        the full details of the request that was made to invoke the view.

For more information on how to use the built in generic views, consult the next

topic on :doc:`generic class based views</topics/class-based-views/generic-display>`.

.. _supporting-other-http-methods:

Supporting other HTTP methods

-----------------------------

Suppose somebody wants to access our book library over HTTP using the views

as an API. The API client would connect every now and then and download book

data for the books published since last visit. But if no new books appeared

since then, it is a waste of CPU time and bandwidth to fetch the books from the

database, render a full response and send it to the client. It might be

preferable to ask the API when the most recent book was published.

We map the URL to book list view in the URLconf::

    from django.conf.urls import patterns

    from books.views import BookListView

    urlpatterns = patterns('',

        (r'^books/$', BookListView.as_view()),

    )

And the view::

    from django.http import HttpResponse

    from django.views.generic import ListView

    from books.models import Book

    class BookListView(ListView):

        model = Book

        def head(self, *args, **kwargs):

            last_book = self.get_queryset().latest('publication_date')

            response = HttpResponse('')

            # RFC 1123 date format

            response['Last-Modified'] = last_book.publication_date.strftime('%a, %d %b %Y %H:%M:%S GMT')

            return response

If the view is accessed from a ``GET`` request, a plain-and-simple object

list is returned in the response (using ``book_list.html`` template). But if

the client issues a ``HEAD`` request, the response has an empty body and

the ``Last-Modified`` header indicates when the most recent book was published.

Based on this information, the client may or may not download the full object

list.

Decorating class-based views

============================