Updated ReferenceField's to optionally store ObjectId strings.

This will become the default in 0.8 (MongoEngine/mongoengine#89)

tests/test_dereference.py

@@ -64,6 +64,130 @@ class FieldTest(unittest.TestCase):
         User.drop_collection()
         Group.drop_collection()
 
+    def test_list_item_dereference_dref_false(self):
+        """Ensure that DBRef items in ListFields are dereferenced.
+        """
+        class User(Document):
+            name = StringField()
+
+        class Group(Document):
+            members = ListField(ReferenceField(User, dbref=False))
+
+        User.drop_collection()
+        Group.drop_collection()
+
+        for i in xrange(1, 51):
+            user = User(name='user %s' % i)
+            user.save()
+
+        group = Group(members=User.objects)
+        group.save()
+
+        with query_counter() as q:
+            self.assertEqual(q, 0)
+
+            group_obj = Group.objects.first()
+            self.assertEqual(q, 1)
+
+            [m for m in group_obj.members]
+            self.assertEqual(q, 2)
+
+        # Document select_related
+        with query_counter() as q:
+            self.assertEqual(q, 0)
+
+            group_obj = Group.objects.first().select_related()
+
+            self.assertEqual(q, 2)
+            [m for m in group_obj.members]
+            self.assertEqual(q, 2)
+
+        # Queryset select_related
+        with query_counter() as q:
+            self.assertEqual(q, 0)
+            group_objs = Group.objects.select_related()
+            self.assertEqual(q, 2)
+            for group_obj in group_objs:
+                [m for m in group_obj.members]
+                self.assertEqual(q, 2)
+
+        User.drop_collection()
+        Group.drop_collection()
+
+    def test_handle_old_style_references(self):
+        """Ensure that DBRef items in ListFields are dereferenced.
+        """
+        class User(Document):
+            name = StringField()
+
+        class Group(Document):
+            members = ListField(ReferenceField(User, dbref=True))
+
+        User.drop_collection()
+        Group.drop_collection()
+
+        for i in xrange(1, 26):
+            user = User(name='user %s' % i)
+            user.save()
+
+        group = Group(members=User.objects)
+        group.save()
+
+        group = Group._get_collection().find_one()
+
+        # Update the model to change the reference
+        class Group(Document):
+            members = ListField(ReferenceField(User, dbref=False))
+
+        group = Group.objects.first()
+        group.members.append(User(name="String!").save())
+        group.save()
+
+        group = Group.objects.first()
+        self.assertEqual(group.members[0].name, 'user 1')
+        self.assertEqual(group.members[-1].name, 'String!')
+
+    def test_migrate_references(self):
+        """Example of migrating ReferenceField storage
+        """
+
+        # Create some sample data
+        class User(Document):
+            name = StringField()
+
+        class Group(Document):
+            author = ReferenceField(User, dbref=True)
+            members = ListField(ReferenceField(User, dbref=True))
+
+        User.drop_collection()
+        Group.drop_collection()
+
+        user = User(name="Ross").save()
+        group = Group(author=user, members=[user]).save()
+
+        raw_data = Group._get_collection().find_one()
+        self.assertTrue(isinstance(raw_data['author'], DBRef))
+        self.assertTrue(isinstance(raw_data['members'][0], DBRef))
+
+        # Migrate the model definition
+        class Group(Document):
+            author = ReferenceField(User, dbref=False)
+            members = ListField(ReferenceField(User, dbref=False))
+
+        # Migrate the data
+        for g in Group.objects():
+            g.author = g.author
+            g.members = g.members
+            g.save()
+
+        group = Group.objects.first()
+        self.assertEqual(group.author, user)
+        self.assertEqual(group.members, [user])
+
+        raw_data = Group._get_collection().find_one()
+        self.assertTrue(isinstance(raw_data['author'], basestring))
+        self.assertTrue(isinstance(raw_data['members'][0], basestring))
+
     def test_recursive_reference(self):
         """Ensure that ReferenceFields can reference their own documents.
         """