Commit 593810a5 authored by Jacob Kaplan-Moss's avatar Jacob Kaplan-Moss
Browse files

Fixed #7904: added support for a "use_for_related_fields" property on... 

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
parent c768bc6f

django/db/models/fields/related.py

+8 −1
Original line number Diff line number Diff line
@@ -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

docs/model-api.txt

+11 −0
Original line number Diff line number Diff line
@@ -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

=============

tests/regressiontests/reverse_single_related/models.py

+14 −3
Original line number Diff line number Diff line
@@ -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.



"""}