root/django/branches/sqlalchemy/docs/sitemaps.txt

=====================
The sitemap framework
=====================

**New in Django development version**.

Django comes with a high-level sitemap-generating framework that makes
creating sitemap_ XML files easy.

.. _sitemap: http://www.sitemaps.org/

Overview
========

A sitemap is an XML file on your Web site that tells search-engine indexers how
frequently your pages change and how "important" certain pages are in relation
to other pages on your site. This information helps search engines index your
site.

The Django sitemap framework automates the creation of this XML file by letting
you express this information in Python code.

It works much like Django's `syndication framework`_. To create a sitemap, just
write a ``Sitemap`` class and point to it in your URLconf_.

.. _syndication framework: ../syndication/
.. _URLconf: ../url_dispatch/

Installation
============

To install the sitemap app, follow these steps:

    1. Add ``'django.contrib.sitemaps'`` to your INSTALLED_APPS_ setting.
    2. Make sure ``'django.template.loaders.app_directories.load_template_source'``
       is in your TEMPLATE_LOADERS_ setting. It's in there by default, so
       you'll only need to change this if you've changed that setting.
    3. Make sure you've installed the `sites framework`_.

(Note: The sitemap application doesn't install any database tables. The only
reason it needs to go into ``INSTALLED_APPS`` is so that the
``load_template_source`` template loader can find the default templates.)

.. _INSTALLED_APPS: ../settings/#installed-apps
.. _TEMPLATE_LOADERS: ../settings/#template-loaders
.. _sites framework: ../sites/

Initialization
==============

To activate sitemap generation on your Django site, add this line to your
URLconf_:

    (r'^sitemap.xml$', 'django.contrib.sitemaps.views.sitemap', {'sitemaps': sitemaps})

This tells Django to build a sitemap when a client accesses ``/sitemap.xml``.

The name of the sitemap file is not important, but the location is. Search
engines will only index links in your sitemap for the current URL level and
below. For instance, if ``sitemap.xml`` lives in your root directory, it may
reference any URL in your site. However, if your sitemap lives at
``/content/sitemap.xml``, it may only reference URLs that begin with
``/content/``.

The sitemap view takes an extra, required argument: ``{'sitemaps': sitemaps}``.
``sitemaps`` should be a dictionary that maps a short section label (e.g.,
``blog`` or ``news``) to its ``Sitemap`` class (e.g., ``BlogSitemap`` or
``NewsSitemap``). It may also map to an *instance* of a ``Sitemap`` class
(e.g., ``BlogSitemap(some_var)``).

.. _URLconf: ../url_dispatch/

Sitemap classes
===============

A ``Sitemap`` class is a simple Python class that represents a "section" of
entries in your sitemap. For example, one ``Sitemap`` class could represent all
the entries of your weblog, while another could represent all of the events in
your events calendar.

In the simplest case, all these sections get lumped together into one
``sitemap.xml``, but it's also possible to use the framework to generate a
sitemap index that references individual sitemap files, one per section. (See
`Creating a sitemap index`_ below.)

``Sitemap`` classes must subclass ``django.contrib.sitemaps.Sitemap``. They can
live anywhere in your codebase.

A simple example
================

Let's assume you have a blog system, with an ``Entry`` model, and you want your
sitemap to include all the links to your individual blog entries. Here's how
your sitemap class might look::

    from django.contrib.sitemaps import Sitemap
    from mysite.blog.models import Entry

    class BlogSitemap(Sitemap):
        changefreq = "never"
        priority = 0.5

        def items(self):
            return Entry.objects.filter(is_draft=False)

        def lastmod(self, obj):
            return obj.pub_date

Note:

    * ``changefreq`` and ``priority`` are class attributes corresponding to
      ``<changefreq>`` and ``<priority>`` elements, respectively. They can be
      made callable as functions, as ``lastmod`` was in the example.
    * ``items()`` is simply a method that returns a list of objects. The objects
      returned will get passed to any callable methods corresponding to a
      sitemap property (``location``, ``lastmod``, ``changefreq``, and
      ``priority``).
    * ``lastmod`` should return a Python ``datetime`` object.
    * There is no ``location`` method in this example, but you can provide it
      in order to specify the URL for your object. By default, ``location()``
      calls ``get_absolute_url()`` on each object and returns the result.

Sitemap class reference
=======================

A ``Sitemap`` class can define the following methods/attributes:

``items``
---------

**Required.** A method that returns a list of objects. The framework doesn't
care what *type* of objects they are; all that matters is that these objects
get passed to the ``location()``, ``lastmod()``, ``changefreq()`` and
``priority()`` methods.

``location``
------------

**Optional.** Either a method or attribute.

If it's a method, it should return the absolute URL for a given object as
returned by ``items()``.

If it's an attribute, its value should be a string representing an absolute URL
to use for *every* object returned by ``items()``.

In both cases, "absolute URL" means a URL that doesn't include the protocol or
domain. Examples:

    * Good: ``'/foo/bar/'``
    * Bad: ``'example.com/foo/bar/'``
    * Bad: ``'http://example.com/foo/bar/'``

If ``location`` isn't provided, the framework will call the
``get_absolute_url()`` method on each object as returned by ``items()``.

``lastmod``
-----------

**Optional.** Either a method or attribute.

If it's a method, it should take one argument -- an object as returned by
``items()`` -- and return that object's last-modified date/time, as a Python
``datetime.datetime`` object.

If it's an attribute, its value should be a Python ``datetime.datetime`` object
representing the last-modified date/time for *every* object returned by
``items()``.

``changefreq``
--------------

**Optional.** Either a method or attribute.

If it's a method, it should take one argument -- an object as returned by
``items()`` -- and return that object's change frequency, as a Python string.

If it's an attribute, its value should be a string representing the change
frequency of *every* object returned by ``items()``.

Possible values for ``changefreq``, whether you use a method or attribute, are:

    * ``'always'``
    * ``'hourly'``
    * ``'daily'``
    * ``'weekly'``
    * ``'monthly'``
    * ``'yearly'``
    * ``'never'``

``priority``
------------

**Optional.** Either a method or attribute.

If it's a method, it should take one argument -- an object as returned by
``items()`` -- and return that object's priority, as either a string or float.

If it's an attribute, its value should be either a string or float representing
the priority of *every* object returned by ``items()``.

Example values for ``priority``: ``0.4``, ``1.0``. The default priority of a
page is ``0.5``. See the `sitemaps.org documentation`_ for more.

.. _sitemaps.org documentation: http://www.sitemaps.org/protocol.html#prioritydef

Shortcuts
=========

The sitemap framework provides a couple convenience classes for common cases:

``FlatPageSitemap``
-------------------

The ``django.contrib.sitemaps.FlatPageSitemap`` class looks at all flatpages_
defined for the current ``SITE_ID`` (see the `sites documentation`_) and
creates an entry in the sitemap. These entries include only the ``location``
attribute -- not ``lastmod``, ``changefreq`` or ``priority``.

.. _flatpages: ../flatpages/
.. _sites documentation: ../sites/

``GenericSitemap``
------------------

The ``GenericSitemap`` class works with any `generic views`_ you already have.
To use it, create an instance, passing in the same ``info_dict`` you pass to
the generic views. The only requirement is that the dictionary have a
``queryset`` entry. It may also have a ``date_field`` entry that specifies a
date field for objects retrieved from the ``queryset``. This will be used for
the ``lastmod`` attribute in the generated sitemap. You may also pass
``priority`` and ``changefreq`` keyword arguments to the ``GenericSitemap``
constructor to specify these attributes for all URLs.

.. _generic views: ../generic_views/

Example
-------

Here's an example of a URLconf_ using both::

    from django.conf.urls.defaults import *
    from django.contrib.sitemaps import FlatPageSitemap, GenericSitemap
    from mysite.blog.models import Entry

    info_dict = {
        'queryset': Entry.objects.all(),
        'date_field': 'pub_date',
    }

    sitemaps = {
        'flatpages': FlatPageSitemap,
        'blog': GenericSitemap(info_dict, priority=0.6),
    }

    urlpatterns = patterns('',
        # some generic view using info_dict
        # ...

        # the sitemap
        (r'^sitemap.xml$', 'django.contrib.sitemaps.views.sitemap', {'sitemaps': sitemaps})
    )

.. _URLconf: ../url_dispatch/

Creating a sitemap index
========================

The sitemap framework also has the ability to create a sitemap index that
references individual sitemap files, one per each section defined in your
``sitemaps`` dictionary. The only differences in usage are:

    * You use two views in your URLconf: ``django.contrib.sitemaps.views.index``
      and ``django.contrib.sitemaps.views.sitemap``.
    * The ``django.contrib.sitemaps.views.sitemap`` view should take a
      ``section`` keyword argument.

Here is what the relevant URLconf lines would look like for the example above::

    (r'^sitemap.xml$', 'django.contrib.sitemaps.views.index', {'sitemaps': sitemaps})
    (r'^sitemap-(?P<section>.+).xml$', 'django.contrib.sitemaps.views.sitemap', {'sitemaps': sitemaps})

This will automatically generate a ``sitemap.xml`` file that references
both ``sitemap-flatpages.xml`` and ``sitemap-blog.xml``. The ``Sitemap``
classes and the ``sitemaps`` dict don't change at all.

Pinging Google
==============

You may want to "ping" Google when your sitemap changes, to let it know to
reindex your site. The framework provides a function to do just that:
``django.contrib.sitemaps.ping_google()``.

``ping_google()`` takes an optional argument, ``sitemap_url``, which should be
the absolute URL of your site's sitemap (e.g., ``'/sitemap.xml'``). If this
argument isn't provided, ``ping_google()`` will attempt to figure out your
sitemap by performing a reverse looking in your URLconf.

``ping_google()`` raises the exception
``django.contrib.sitemaps.SitemapNotFound`` if it cannot determine your sitemap
URL.

One useful way to call ``ping_google()`` is from a model's ``save()`` method::

    from django.contrib.sitemaps import ping_google

    class Entry(models.Model):
        # ...
        def save(self):
            super(Entry, self).save()
            try:
                ping_google()
            except Exception:
                # Bare 'except' because we could get a variety
                # of HTTP-related exceptions.
                pass

A more efficient solution, however, would be to call ``ping_google()`` from a
cron script, or some other scheduled task. The function makes an HTTP request
to Google's servers, so you may not want to introduce that network overhead
each time you call ``save()``.