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Fixed #6188, #6304, #6618, #6969, #8758, #8989, #10334, #11069, #11973 and #12403 -- Modified the syndication framework to use class-based views. Thanks to Ben Firshman for his work on this patch.

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git-svn-id: http://code.djangoproject.com/svn/django/trunk@12338 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Russell Keith-Magee 2010-01-28 13:46:18 +00:00
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docs/ref/contrib/syndication.txt
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@ -8,14 +8,15 @@ The syndication feed framework
:synopsis: A framework for generating syndication feeds, in RSS and Atom,
quite easily.
Django comes with a high-level syndication-feed-generating framework that makes
creating RSS_ and Atom_ feeds easy.
Django comes with a high-level syndication-feed-generating framework
that makes creating RSS_ and Atom_ feeds easy.
To create any syndication feed, all you have to do is write a short Python
class. You can create as many feeds as you want.
To create any syndication feed, all you have to do is write a short
Python class. You can create as many feeds as you want.
Django also comes with a lower-level feed-generating API. Use this if you want
to generate feeds outside of a Web context, or in some other lower-level way.
Django also comes with a lower-level feed-generating API. Use this if
you want to generate feeds outside of a Web context, or in some other
lower-level way.
.. _RSS: http://www.whatisrss.com/
.. _Atom: http://www.atomenabled.org/
@ -23,74 +24,37 @@ to generate feeds outside of a Web context, or in some other lower-level way.
The high-level framework
========================
.. versionchanged:: 1.2
The high-level feeds framework was refactored in Django 1.2. The
pre-1.2 interface still exists, but it has been deprecated, and
will be removed in Django 1.4. If you need to maintain an old-style
Django feed, please consult the Django 1.1 documentation. For
details on updating to use the new high-level feed framework, see
the :ref:`Django 1.2 release notes <1.2-updating-feeds>`.
Overview
--------
The high-level feed-generating framework is a view that's hooked to ``/feeds/``
by default. Django uses the remainder of the URL (everything after ``/feeds/``)
to determine which feed to output.
To create a feed, just write a :class:`~django.contrib.syndication.feeds.Feed`
class and point to it in your :ref:`URLconf <topics-http-urls>`.
Initialization
--------------
To activate syndication feeds on your Django site, add this line to your
:ref:`URLconf <topics-http-urls>`::
(r'^feeds/(?P<url>.*)/$', 'django.contrib.syndication.views.feed', {'feed_dict': feeds}),
This tells Django to use the RSS framework to handle all URLs starting with
:file:`"feeds/"`. (You can change that :file:`"feeds/"` prefix to fit your own
needs.)
This URLconf line has an extra argument: ``{'feed_dict': feeds}``. Use this
extra argument to pass the syndication framework the feeds that should be
published under that URL.
Specifically, :data:`feed_dict` should be a dictionary that maps a feed's slug
(short URL label) to its :class:`~django.contrib.syndication.feeds.Feed` class.
You can define the ``feed_dict`` in the URLconf itself. Here's a full example
URLconf::
from django.conf.urls.defaults import *
from myproject.feeds import LatestEntries, LatestEntriesByCategory
feeds = {
'latest': LatestEntries,
'categories': LatestEntriesByCategory,
}
urlpatterns = patterns('',
# ...
(r'^feeds/(?P<url>.*)/$', 'django.contrib.syndication.views.feed',
{'feed_dict': feeds}),
# ...
)
The above example registers two feeds:
* The feed represented by ``LatestEntries`` will live at ``feeds/latest/``.
* The feed represented by ``LatestEntriesByCategory`` will live at
``feeds/categories/``.
Once that's set up, you just need to define the
:class:`~django.contrib.syndication.feeds.Feed` classes themselves.
The high-level feed-generating framework is supplied by the
:class:`~django.contrib.syndication.views.Feed` class. To create a
feed, write a :class:`~django.contrib.syndication.views.Feed` class
and point to an instance of it in your :ref:`URLconf
<topics-http-urls>`.
Feed classes
------------
A :class:`~django.contrib.syndication.feeds.Feed` class is a simple Python class
that represents a syndication feed. A feed can be simple (e.g., a "site news"
feed, or a basic feed displaying the latest entries of a blog) or more complex
(e.g., a feed displaying all the blog entries in a particular category, where
the category is variable).
A :class:`~django.contrib.syndication.views.Feed` class is a Python
class that represents a syndication feed. A feed can be simple (e.g.,
a "site news" feed, or a basic feed displaying the latest entries of a
blog) or more complex (e.g., a feed displaying all the blog entries in
a particular category, where the category is variable).
:class:`~django.contrib.syndication.feeds.Feed` classes must subclass
``django.contrib.syndication.feeds.Feed``. They can live anywhere in your
codebase.
Feed classes subclass :class:`django.contrib.syndication.views.Feed`.
They can live anywhere in your codebase.
Instances of :class:`~django.contrib.syndication.views.Feed` classes
are views which can be used in your :ref:`URLconf <topics-http-urls>`.
A simple example
----------------
@ -98,10 +62,10 @@ A simple example
This simple example, taken from `chicagocrime.org`_, describes a feed of the
latest five news items::
from django.contrib.syndication.feeds import Feed
from django.contrib.syndication.views import Feed
from chicagocrime.models import NewsItem
class LatestEntries(Feed):
class LatestEntriesFeed(Feed):
title = "Chicagocrime.org site news"
link = "/sitenews/"
description = "Updates on changes and additions to chicagocrime.org."
@ -109,9 +73,27 @@ latest five news items::
def items(self):
return NewsItem.objects.order_by('-pub_date')[:5]
def item_title(self, item):
return item.title
def item_description(self, item):
return item.description
To connect a URL to this feed, put an instance of the Feed object in
your :ref:`URLconf <topics-http-urls>`. For example::
from django.conf.urls.defaults import *
from myproject.feeds import LatestEntriesFeed
urlpatterns = patterns('',
# ...
(r'^latest/feed/$', LatestEntriesFeed()),
# ...
)
Note:
* The class subclasses ``django.contrib.syndication.feeds.Feed``.
* The Feed class subclasses :class:`django.contrib.syndication.views.Feed`.
* :attr:`title`, :attr:`link` and :attr:`description` correspond to the
standard RSS ``<title>``, ``<link>`` and ``<description>`` elements,
@ -129,17 +111,23 @@ Note:
:attr:`subtitle` attribute instead of the :attr:`description` attribute.
See `Publishing Atom and RSS feeds in tandem`_, later, for an example.
One thing's left to do. In an RSS feed, each ``<item>`` has a ``<title>``,
One thing is left to do. In an RSS feed, each ``<item>`` has a ``<title>``,
``<link>`` and ``<description>``. We need to tell the framework what data to put
into those elements.
* To specify the contents of ``<title>`` and ``<description>``, create
:ref:`Django templates <topics-templates>` called
:file:`feeds/latest_title.html` and
:file:`feeds/latest_description.html`, where :attr:`latest` is the
:attr:`slug` specified in the URLconf for the given feed. Note the
``.html`` extension is required. The RSS system renders that template for
each item, passing it two template context variables:
* For the contents of ``<title>`` and ``<description>``, Django tries
calling the methods :meth:`item_title()` and :meth:`item_description()` on
the :class:`~django.contrib.syndication.views.Feed` class. They are passed
a single parameter, :attr:`item`, which is the object itself. These are
optional; by default, the unicode representation of the object is used for
both.
If you want to do any special formatting for either the title or
description, :ref:`Django templates <topics-templates>` can be used
instead. Their paths can be specified with the ``title_template`` and
``description_template`` attributes on the
:class:`~django.contrib.syndication.views.Feed` class. The templates are
rendered for each item and are passed two template context variables:
* ``{{ obj }}`` -- The current object (one of whichever objects you
returned in :meth:`items()`).
@ -152,152 +140,102 @@ into those elements.
:ref:`RequestSite section of the sites framework documentation
<requestsite-objects>` for more.
If you don't create a template for either the title or description, the
framework will use the template ``"{{ obj }}"`` by default -- that is, the
normal string representation of the object. You can also change the names
of these two templates by specifying ``title_template`` and
``description_template`` as attributes of your
:class:`~django.contrib.syndication.feeds.Feed` class.
See `a complex example`_ below that uses a description template.
* To specify the contents of ``<link>``, you have two options. For each item
in :meth:`items()`, Django first tries calling a method
:meth:`item_link()` in the :class:`~django.contrib.syndication.feeds.Feed`
class, passing it a single parameter, :attr:`item`, which is the object
itself. If that method doesn't exist, Django tries executing a
``get_absolute_url()`` method on that object. . Both
``get_absolute_url()`` and :meth:`item_link()` should return the item's
URL as a normal Python string. As with ``get_absolute_url()``, the result
of :meth:`item_link()` will be included directly in the URL, so you are
responsible for doing all necessary URL quoting and conversion to ASCII
inside the method itself.
* For the LatestEntries example above, we could have very simple feed
templates:
* latest_title.html:
.. code-block:: html+django
{{ obj.title }}
* latest_description.html:
.. code-block:: html+django
{{ obj.description }}
in :meth:`items()`, Django first tries calling the
:meth:`item_link()` method on the
:class:`~django.contrib.syndication.views.Feed` class. In a similar way to
the title and description, it is passed it a single parameter,
:attr:`item`. If that method doesn't exist, Django tries executing a
``get_absolute_url()`` method on that object. Both
:meth:`get_absolute_url()` and :meth:`item_link()` should return the
item's URL as a normal Python string. As with ``get_absolute_url()``, the
result of :meth:`item_link()` will be included directly in the URL, so you
are responsible for doing all necessary URL quoting and conversion to
ASCII inside the method itself.
.. _chicagocrime.org: http://www.chicagocrime.org/
A complex example
-----------------
The framework also supports more complex feeds, via parameters.
The framework also supports more complex feeds, via arguments.
For example, `chicagocrime.org`_ offers an RSS feed of recent crimes for every
police beat in Chicago. It'd be silly to create a separate
:class:`~django.contrib.syndication.feeds.Feed` class for each police beat; that
:class:`~django.contrib.syndication.views.Feed` class for each police beat; that
would violate the :ref:`DRY principle <dry>` and would couple data to
programming logic. Instead, the syndication framework lets you make generic
feeds that output items based on information in the feed's URL.
programming logic. Instead, the syndication framework lets you access the
arguments passed from your :ref:`URLconf <topics-http-urls>` so feeds can output
items based on information in the feed's URL.
On chicagocrime.org, the police-beat feeds are accessible via URLs like this:
* :file:`/rss/beats/0613/` -- Returns recent crimes for beat 0613.
* :file:`/rss/beats/1424/` -- Returns recent crimes for beat 1424.
* :file:`/beats/613/rss/` -- Returns recent crimes for beat 613.
* :file:`/beats/1424/rss/` -- Returns recent crimes for beat 1424.
The slug here is ``"beats"``. The syndication framework sees the extra URL bits
after the slug -- ``0613`` and ``1424`` -- and gives you a hook to tell it what
those URL bits mean, and how they should influence which items get published in
the feed.
These can be matched with a :ref:`URLconf <topics-http-urls>` line such as::
An example makes this clear. Here's the code for these beat-specific feeds::
(r'^beats/(?P<beat_id>\d+)/rss/$', BeatFeed()),
from django.contrib.syndication.feeds import FeedDoesNotExist
from django.core.exceptions import ObjectDoesNotExist
Like a view, the arguments in the URL are passed to the :meth:`get_object()`
method along with the request object.
.. versionchanged:: 1.2
Prior to version 1.2, ``get_object()`` only accepted a ``bits`` argument.
Here's the code for these beat-specific feeds::
from django.contrib.syndication.views import FeedDoesNotExist
from django.shortcuts import get_object_or_404
class BeatFeed(Feed):
def get_object(self, bits):
# In case of "/rss/beats/0613/foo/bar/baz/", or other such clutter,
# check that bits has only one member.
if len(bits) != 1:
raise ObjectDoesNotExist
return Beat.objects.get(beat__exact=bits[0])
description_template = 'feeds/beat_description.html'
def get_object(self, request, beat_id):
return get_object_or_404(Beat, pk=beat_id)
def title(self, obj):
return "Chicagocrime.org: Crimes for beat %s" % obj.beat
def link(self, obj):
if not obj:
raise FeedDoesNotExist
return obj.get_absolute_url()
def description(self, obj):
return "Crimes recently reported in police beat %s" % obj.beat
def items(self, obj):
return Crime.objects.filter(beat__id__exact=obj.id).order_by('-crime_date')[:30]
return Crime.objects.filter(beat=obj).order_by('-crime_date')[:30]
Here's the basic algorithm the RSS framework follows, given this class and a
request to the URL :file:`/rss/beats/0613/`:
To generate the feed's ``<title>``, ``<link>`` and ``<description>``, Django
uses the :meth:`title()`, :meth:`link()` and :meth:`description()` methods. In
the previous example, they were simple string class attributes, but this example
illustrates that they can be either strings *or* methods. For each of
:attr:`title`, :attr:`link` and :attr:`description`, Django follows this
algorithm:
* The framework gets the URL :file:`/rss/beats/0613/` and notices there's an
extra bit of URL after the slug. It splits that remaining string by the
slash character (``"/"``) and calls the
:class:`~django.contrib.syndication.feeds.Feed` class'
:meth:`get_object()` method, passing it the bits. In this case, bits is
``['0613']``. For a request to :file:`/rss/beats/0613/foo/bar/`, bits
would be ``['0613', 'foo', 'bar']``.
* First, it tries to call a method, passing the ``obj`` argument, where
``obj`` is the object returned by :meth:`get_object()`.
* :meth:`get_object()` is responsible for retrieving the given beat, from
the given ``bits``. In this case, it uses the Django database API to
retrieve the beat. Note that :meth:`get_object()` should raise
:exc:`django.core.exceptions.ObjectDoesNotExist` if given invalid
parameters. There's no ``try``/``except`` around the
``Beat.objects.get()`` call, because it's not necessary; that function
raises :exc:`Beat.DoesNotExist` on failure, and :exc:`Beat.DoesNotExist`
is a subclass of :exc:`ObjectDoesNotExist`. Raising
:exc:`ObjectDoesNotExist` in :meth:`get_object()` tells Django to produce
a 404 error for that request.
* Failing that, it tries to call a method with no arguments.
.. versionadded:: 1.0
:meth:`get_object()` can handle the :file:`/rss/beats/` url.
* Failing that, it uses the class attribute.
The :meth:`get_object()` method also has a chance to handle the
:file:`/rss/beats/` url. In this case, :data:`bits` will be an
empty list. In our example, ``len(bits) != 1`` and an
:exc:`ObjectDoesNotExist` exception will be raised, so
:file:`/rss/beats/` will generate a 404 page. But you can handle this case
however you like. For example, you could generate a combined feed for all
beats.
Also note that :meth:`items()` also follows the same algorithm -- first, it
tries :meth:`items(obj)`, then :meth:`items()`, then finally an :attr:`items`
class attribute (which should be a list).
* To generate the feed's ``<title>``, ``<link>`` and ``<description>``,
Django uses the :meth:`title()`, :meth:`link()` and :meth:`description()`
methods. In the previous example, they were simple string class
attributes, but this example illustrates that they can be either strings
*or* methods. For each of :attr:`title`, :attr:`link` and
:attr:`description`, Django follows this algorithm:
We are using a template for the item descriptions. It can be very simple:
* First, it tries to call a method, passing the ``obj`` argument, where
``obj`` is the object returned by :meth:`get_object()`.
.. code-block:: html+django
* Failing that, it tries to call a method with no arguments.
{{ obj.description }}
* Failing that, it uses the class attribute.
Inside the :meth:`link()` method, we handle the possibility that ``obj``
might be ``None``, which can occur when the URL isn't fully specified. In
some cases, you might want to do something else in this case, which would
mean you'd need to check for ``obj`` existing in other methods as well.
(The :meth:`link()` method is called very early in the feed generation
process, so it's a good place to bail out early.)
* Finally, note that :meth:`items()` in this example also takes the ``obj``
argument. The algorithm for :attr:`items` is the same as described in the
previous step -- first, it tries :meth:`items(obj)`, then :meth:`items()`,
then finally an :attr:`items` class attribute (which should be a list).
However, you are free to add formatting as desired.
The ``ExampleFeed`` class below gives full documentation on methods and
attributes of :class:`~django.contrib.syndication.feeds.Feed` classes.
attributes of :class:`~django.contrib.syndication.views.Feed` classes.
Specifying the type of feed
---------------------------
@ -305,7 +243,7 @@ Specifying the type of feed
By default, feeds produced in this framework use RSS 2.0.
To change that, add a ``feed_type`` attribute to your
:class:`~django.contrib.syndication.feeds.Feed` class, like so::
:class:`~django.contrib.syndication.views.Feed` class, like so::
from django.utils.feedgenerator import Atom1Feed
@ -353,13 +291,13 @@ Publishing Atom and RSS feeds in tandem
Some developers like to make available both Atom *and* RSS versions of their
feeds. That's easy to do with Django: Just create a subclass of your
:class:`~django.contrib.syndication.feeds.Feed`
:class:`~django.contrib.syndication.views.Feed`
class and set the :attr:`feed_type` to something different. Then update your
URLconf to add the extra versions.
Here's a full example::
from django.contrib.syndication.feeds import Feed
from django.contrib.syndication.views import Feed
from chicagocrime.models import NewsItem
from django.utils.feedgenerator import Atom1Feed
@ -381,7 +319,7 @@ Here's a full example::
a feed-level "description," but they *do* provide for a "subtitle."
If you provide a :attr:`description` in your
:class:`~django.contrib.syndication.feeds.Feed` class, Django will *not*
:class:`~django.contrib.syndication.views.Feed` class, Django will *not*
automatically put that into the :attr:`subtitle` element, because a
subtitle and description are not necessarily the same thing. Instead, you
should define a :attr:`subtitle` attribute.
@ -394,56 +332,50 @@ And the accompanying URLconf::
from django.conf.urls.defaults import *
from myproject.feeds import RssSiteNewsFeed, AtomSiteNewsFeed
feeds = {
'rss': RssSiteNewsFeed,
'atom': AtomSiteNewsFeed,
}
urlpatterns = patterns('',
# ...
(r'^feeds/(?P<url>.*)/$', 'django.contrib.syndication.views.feed',
{'feed_dict': feeds}),
(r'^sitenews/rss/$', RssSiteNewsFeed()),
(r'^sitenews/atom/$', AtomSiteNewsFeed()),
# ...
)
Feed class reference
--------------------
.. class:: django.contrib.syndication.feeds.Feed
.. class:: django.contrib.syndication.views.Feed
This example illustrates all possible attributes and methods for a
:class:`~django.contrib.syndication.feeds.Feed` class::
:class:`~django.contrib.syndication.views.Feed` class::
from django.contrib.syndication.feeds import Feed
from django.contrib.syndication.views import Feed
from django.utils import feedgenerator
class ExampleFeed(Feed):
# FEED TYPE -- Optional. This should be a class that subclasses
# django.utils.feedgenerator.SyndicationFeed. This designates which
# type of feed this should be: RSS 2.0, Atom 1.0, etc.
# If you don't specify feed_type, your feed will be RSS 2.0.
# This should be a class, not an instance of the class.
# django.utils.feedgenerator.SyndicationFeed. This designates
# which type of feed this should be: RSS 2.0, Atom 1.0, etc. If
# you don't specify feed_type, your feed will be RSS 2.0. This
# should be a class, not an instance of the class.
feed_type = feedgenerator.Rss201rev2Feed
# TEMPLATE NAMES -- Optional. These should be strings representing
# names of Django templates that the system should use in rendering the
# title and description of your feed items. Both are optional.
# If you don't specify one, or either, Django will use the template
# 'feeds/SLUG_title.html' and 'feeds/SLUG_description.html', where SLUG
# is the slug you specify in the URL.
# TEMPLATE NAMES -- Optional. These should be strings
# representing names of Django templates that the system should
# use in rendering the title and description of your feed items.
# Both are optional. If a template is not specified, the
# item_title() or item_description() methods are used instead.
title_template = None
description_template = None
# TITLE -- One of the following three is required. The framework looks
# for them in this order.
# TITLE -- One of the following three is required. The framework
# looks for them in this order.
def title(self, obj):
"""
Takes the object returned by get_object() and returns the feed's
title as a normal Python string.
Takes the object returned by get_object() and returns the
feed's title as a normal Python string.
"""
def title(self):
@ -453,13 +385,13 @@ This example illustrates all possible attributes and methods for a
title = 'foo' # Hard-coded title.
# LINK -- One of the following three is required. The framework looks
# for them in this order.
# LINK -- One of the following three is required. The framework
# looks for them in this order.
def link(self, obj):
"""
Takes the object returned by get_object() and returns the feed's
link as a normal Python string.
# Takes the object returned by get_object() and returns the feed's
# link as a normal Python string.
"""
def link(self):
@ -572,18 +504,18 @@ This example illustrates all possible attributes and methods for a
# COPYRIGHT NOTICE -- One of the following three is optional. The
# framework looks for them in this order.
def copyright(self, obj):
def feed_copyright(self, obj):
"""
Takes the object returned by get_object() and returns the feed's
copyright notice as a normal Python string.
"""
def copyright(self):
def feed_copyright(self):
"""
Returns the feed's copyright notice as a normal Python string.
"""
copyright = 'Copyright (c) 2007, Sally Smith' # Hard-coded copyright notice.
feed_copyright = 'Copyright (c) 2007, Sally Smith' # Hard-coded copyright notice.
# TTL -- One of the following three is optional. The framework looks
# for them in this order. Ignored for Atom feeds.
@ -620,13 +552,44 @@ This example illustrates all possible attributes and methods for a
# GET_OBJECT -- This is required for feeds that publish different data
# for different URL parameters. (See "A complex example" above.)
def get_object(self, bits):
def get_object(self, request, *args, **kwargs):
"""
Takes a list of strings gleaned from the URL and returns an object
represented by this feed. Raises
Takes the current request and the arguments from the URL, and
returns an object represented by this feed. Raises
django.core.exceptions.ObjectDoesNotExist on error.
"""
# ITEM TITLE AND DESCRIPTION -- If title_template or
# description_template are not defined, these are used instead. Both are
# optional, by default they will use the unicode representation of the
# item.
def item_title(self, item):
"""
Takes an item, as returned by items(), and returns the item's
title as a normal Python string.
"""
def item_title(self):
"""
Returns the title for every item in the feed.
"""
item_title = 'Breaking News: Nothing Happening' # Hard-coded title.
def item_description(self, item):
"""
Takes an item, as returned by items(), and returns the item's
description as a normal Python string.
"""
def item_description(self):
"""
Returns the description for every item in the feed.
"""
item_description = 'A description of the item.' # Hard-coded description.
# ITEM LINK -- One of these three is required. The framework looks for
# them in this order.
@ -686,7 +649,7 @@ This example illustrates all possible attributes and methods for a
item_author_email = 'test@example.com' # Hard-coded author e-mail.
# ITEM AUTHOR LINK --One of the following three is optional. The
# ITEM AUTHOR LINK -- One of the following three is optional. The
# framework looks for them in this order. In each case, the URL should
# include the "http://" and domain name.
#