==============
URL dispatcher
==============

We're fanatics about good URLs. No ".php" or ".cgi", and certainly not any of
that "0,2097,1-1-1928,00" nonsense. Django's URL dispatcher lets you design
your URLs to be as pretty as the rest of your application.

See `the Django overview`_ for a quick introduction to URL configurations; this
document will continue from there.

.. _`the Django overview`: http://www.djangoproject.com/documentation/overview/#design-your-urls

The view prefix
===============

Here's the example from that overview::

    from django.conf.urls.defaults import *

    urlpatterns = patterns('',
        (r'^/articles/(?P<year>\d{4})/$', 'myproject.news.views.articles.year_archive'),
        (r'^/articles/(?P<year>\d{4})/(?P<month>\d{2})/$', 'myproject.news.views.articles.month_archive'),
        (r'^/articles/(?P<year>\d{4})/(?P<month>\d{2})/(?P<day>\d+)/$', 'myproject.news.views.articles.article_detail'),
    )

The first argument to ``patterns`` is an empty string in the above example, but
that argument can be useful. The first argument is prepended to all the view
functions in the urlpatterns list, so the above example could be written more
concisely as::

    urlpatterns = patterns('myproject.news.views.articles',
        (r'^/articles/(?P<year>\d{4})/$', 'year_archive'),
        (r'^/articles/(?P<year>\d{4})/(?P<month>\d{2})/$', 'month_archive'),
        (r'^/articles/(?P<year>\d{4})/(?P<month>\d{2})/(?P<day>\d+)/$', 'article_detail'),
    )

.. admonition:: Note

    More precisely, the actual view function used is ``prefix + "." +
    function_name``. The trailing "dot" does not need to be put in the prefix.

Including other URLconfs
========================

You can also "include" other URLconf modules at any point along the path. This
essentially "roots" a set of URLs below other ones.  This is most often used
for a site's "base" URLconf; the ``ROOT_URLCONF`` setting points to a urlconf
module that will be used for the entire site. Here's the URLconf for the
`Django website`_ itself. It includes a number of other URLconfs::

    from django.conf.urls.defaults import *

    urlpatterns = patterns('',
        (r'^weblog/',        include('django_website.apps.blog.urls.blog')),
        (r'^documentation/', include('django_website.apps.docs.urls.docs')),
        (r'^comments/',      include('django.contrib.comments.urls.comments')),
        (r'^rss/',           include('django.conf.urls.rss')),
    )

Note that an included URLconf receives any captured parameters from parent
URLconfs, so the following example is valid::

    # In settings/urls/main.py
    urlpatterns = patterns('',
        (r'^(?P<username>\w+)/blog/', include('foo.urls.blog')),
    )

    # In foo/urls/blog.py
    urlpatterns = patterns('foo.views'
        (r'^$', 'blog.index'),
        (r'^archive/$', 'blog.archive'),

In the above example, the captured ``"username"`` variable is passed to the
included URLconf, as expected.

.. _`Django website`: http://www.djangoproject.com/

Passing extra options to view functions
=======================================

There are two ways of passing arguments into your view functions: named captures
from the regex (which you've already seen) and the optional third element
in URLconf tuples. This third element can be a dictionary of extra keyword
arguments that will be passed to the view function::

    urlpatterns = patterns('myproject.news.views.articles',
        (r'^/articles/(?P<year>\d{4})/$', 'year_archive', {key: value, key2: value2}),
    )