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

django/db/models/fields/related.py

@@ -239,7 +239,14 @@ def __get__(self, instance, instance_type=None):
                 params = {'%s__pk' % self.field.rel.field_name: val}
             else:
                 params = {'%s__exact' % self.field.rel.field_name: val}
-            rel_obj = QuerySet(self.field.rel.to).get(**params)
+
+            # 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

@@ -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

@@ -26,18 +26,29 @@ class Item(models.Model):
 >>> 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>]
 
 >>> 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.
+
 """}