Adding a GFKOptimizedQuerySet that will allow efficient lookups across

the GFK and used transparently by the RelatedObjectsDescriptor if the
to_object is a GFK (thanks Alex for the ideas on implementation)

genericm2m/genericm2m_tests/tests.py

@@ -1,6 +1,6 @@
 from django.test import TestCase
 
-from genericm2m.models import RelatedObject, RelatedObjectsDescriptor
+from genericm2m.models import RelatedObject, RelatedObjectsDescriptor, GFKOptimizedQuerySet
 from genericm2m.genericm2m_tests.models import Food, Beverage, Person, RelatedBeverage, Boring
 
 
@@ -216,3 +216,14 @@ def test_custom_model_level(self):
             (self.pizza, self.beer),
             (self.pizza, self.soda),
         ), 'food', 'beverage')
+
+    def test_generic_traversal(self):
+        self.pizza.related.connect(self.beer)
+        self.pizza.related.connect(self.soda)
+        self.pizza.related.connect(self.mario)
+
+        related = self.pizza.related.all()
+        self.assertEqual(type(related), GFKOptimizedQuerySet)
+
+        objects = related.generic_objects()
+        self.assertEqual(objects, [self.mario, self.soda, self.beer])

genericm2m/models.py

@@ -1,6 +1,40 @@
 from django.contrib.contenttypes.generic import GenericForeignKey
 from django.contrib.contenttypes.models import ContentType
 from django.db import models
+from django.db.models.query import QuerySet
+
+
+class GFKOptimizedQuerySet(QuerySet):
+    def get_gfk(self):
+        for field in self.model._meta.virtual_fields:
+            if isinstance(field, GenericForeignKey):
+                return field
+
+    def generic_objects(self):
+        clone = self._clone()
+
+        ctypes_and_fks = {}
+
+        gfk_field = self.get_gfk()
+        ctype_field = '%s_id' % gfk_field.ct_field
+        fk_field = gfk_field.fk_field
+
+        for obj in clone:
+            ctype = ContentType.objects.get_for_id(getattr(obj, ctype_field))
+            obj_id = getattr(obj, fk_field)
+
+            ctypes_and_fks.setdefault(ctype, [])
+            ctypes_and_fks[ctype].append(obj_id)
+
+        gfk_objects = {}
+        for ctype, obj_ids in ctypes_and_fks.items():
+            gfk_objects[ctype.pk] = ctype.model_class()._default_manager.in_bulk(obj_ids)
+
+        obj_list = []
+        for obj in clone:
+            obj_list.append(gfk_objects[getattr(obj, ctype_field)][getattr(obj, fk_field)])
+
+        return obj_list
 
 
 class RelatedObjectsDescriptor(object):
@@ -63,10 +97,14 @@ def delete_manager(self, instance):
     def create_manager(self, instance, superclass):
         rel_obj = self
         core_filters = self.get_query_from(instance)
+        uses_gfk = self.is_gfk(self.to_field)
 
         class RelatedManager(superclass):
             def get_query_set(self):
-                return superclass.get_query_set(self).filter(**(core_filters))
+                if uses_gfk:
+                    return GFKOptimizedQuerySet(self.model).filter(**(core_filters))
+                else:
+                    return superclass.get_query_set(self).filter(**(core_filters))
 
             def add(self, *objs):
                 for obj in objs: