Added documentation for CurrentSiteManager to docs/sites.txt

git-svn-id: http://code.djangoproject.com/svn/django/trunk@2962 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Adrian Holovaty 2006-05-22 05:22:45 +00:00
parent 4cb7a2753f
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@ -213,6 +213,56 @@ To do this, you can use the sites framework. A simple example::
>>> 'http://%s%s' % (Site.objects.get_current().domain, obj.get_absolute_url())
'http://example.com/mymodel/objects/3/'
The ``CurrentSiteManager``
==========================
If ``Site``s play a key role in your application, consider using the helpful
``CurrentSiteManager`` in your model(s). It's a model manager_ that
automatically filters its queries to include only objects associated with the
current ``Site``.
Use ``CurrentSiteManager`` by adding it to your model explicitly. For example::
from django.db import models
from django.contrib.sites.models import Site
from django.contrib.sites.managers import CurrentSiteManager
class Photo(models.Model):
photo = models.FileField(upload_to='/home/photos')
photographer_name = models.CharField(maxlength=100)
pub_date = models.DateField()
site = models.ForeignKey(Site)
objects = models.Manager()
on_site = CurrentSiteManager()
With this model, ``Photo.objects.all()`` will return all ``Photo`` objects in
the database, but ``Photo.on_site.all()`` will return only the ``Photo``
objects associated with the current site, according to the ``SITE_ID`` setting.
How did ``CurrentSiteManager`` know which field of ``Photo`` was the ``Site``?
It defaults to looking for a field called ``site``. If your model has a
``ForeignKey`` or ``ManyToManyField`` called something *other* than ``site``,
you need to explicitly pass that as the parameter to ``CurrentSiteManager``.
The following model, which has a field called ``publish_on``, demonstrates
this::
from django.db import models
from django.contrib.sites.models import Site
from django.contrib.sites.managers import CurrentSiteManager
class Photo(models.Model):
photo = models.FileField(upload_to='/home/photos')
photographer_name = models.CharField(maxlength=100)
pub_date = models.DateField()
publish_on = models.ForeignKey(Site)
objects = models.Manager()
on_site = CurrentSiteManager('publish_on')
If you attempt to use ``CurrentSiteManager`` and pass a field name that doesn't
exist, Django will raise a ``ValueError``.
.. _manager: http://www.djangoproject.com/documentation/model_api/#managers
How Django uses the sites framework
===================================