Fixed #7904: added support for a "use_for_related_fields" property on managers. If True, the manager will be used for related object lookups instead of the "bare" QuerySet introduced bu [8107]. Patch from Justin Bronn.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8212 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Jacob Kaplan-Moss 2008-08-05 16:13:28 +00:00
parent c768bc6f25
commit 593810a501
3 changed files with 33 additions and 4 deletions

View File

@ -239,6 +239,13 @@ class ReverseSingleRelatedObjectDescriptor(object):
params = {'%s__pk' % self.field.rel.field_name: val}
else:
params = {'%s__exact' % self.field.rel.field_name: val}
# If the related manager indicates that it should be used for
# related fields, respect that.
rel_mgr = self.field.rel.to._default_manager
if getattr(rel_mgr, 'use_for_related_fields', False):
rel_obj = rel_mgr.get(**params)
else:
rel_obj = QuerySet(self.field.rel.to).get(**params)
setattr(instance, cache_name, rel_obj)
return rel_obj

View File

@ -1507,6 +1507,17 @@ good idea to be careful in your choice of default manager, in order to
avoid a situation where overriding of ``get_query_set()`` results in
an inability to retrieve objects you'd like to work with.
Using managers for related object access
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
By default, Django uses a "bare" (i.e. default) manager when accessing related
objects (i.e. ``choice.poll``). If this default isn't appropriate for your default manager, you can force Django to use a custom manager for related object attributes by giving it a ``use_for_related_fields`` property::
class MyManager(models.Manager)::
use_for_related_fields = True
...
Model methods
=============

View File

@ -26,7 +26,7 @@ __test__ = {'API_TESTS':"""
>>> private_source = Source.objects.create(is_public=False)
>>> private_item = Item.objects.create(source=private_source)
Only one source is available via all() due to the custom default manager.
# Only one source is available via all() due to the custom default manager.
>>> Source.objects.all()
[<Source: Source object>]
@ -34,10 +34,21 @@ Only one source is available via all() due to the custom default manager.
>>> public_item.source
<Source: Source object>
Make sure that an item can still access its related source even if the default
manager doesn't normally allow it.
# Make sure that an item can still access its related source even if the default
# manager doesn't normally allow it.
>>> private_item.source
<Source: Source object>
# If the manager is marked "use_for_related_fields", it'll get used instead
# of the "bare" queryset. Usually you'd define this as a property on the class,
# but this approximates that in a way that's easier in tests.
>>> Source.objects.use_for_related_fields = True
>>> private_item = Item.objects.get(pk=private_item.pk)
>>> private_item.source
Traceback (most recent call last):
...
DoesNotExist: Source matching query does not exist.
"""}