Commit b9f8635f authored by Michal Petrucha's avatar Michal Petrucha Committed by Tim Graham
Browse files

Refs #16508 -- Added invalidation of stale cached instances of GenericForeignKey targets.

parent 7ec330ee

django/contrib/contenttypes/fields.py

+24 −15
Original line number Diff line number Diff line
@@ -208,7 +208,7 @@ class GenericForeignKey(object): 
                lambda obj: (obj._get_pk_val(), obj.__class__),

                gfk_key,

                True,

                self.cache_attr)

                self.name)



    def is_cached(self, instance):

        return hasattr(instance, self.cache_attr)
@@ -217,21 +217,30 @@ class GenericForeignKey(object): 
        if instance is None:

            return self



        # Don't use getattr(instance, self.ct_field) here because that might

        # reload the same ContentType over and over (#5570). Instead, get the

        # content type ID here, and later when the actual instance is needed,

        # use ContentType.objects.get_for_id(), which has a global cache.

        f = self.model._meta.get_field(self.ct_field)

        ct_id = getattr(instance, f.get_attname(), None)

        pk_val = getattr(instance, self.fk_field)



        try:

            return getattr(instance, self.cache_attr)

            rel_obj = getattr(instance, self.cache_attr)

        except AttributeError:

            rel_obj = None

        else:

            if rel_obj and (ct_id != self.get_content_type(obj=rel_obj, using=instance._state.db).id or

                            rel_obj._meta.pk.to_python(pk_val) != rel_obj._get_pk_val()):

                rel_obj = None



        if rel_obj is not None:

            return rel_obj



            # Make sure to use ContentType.objects.get_for_id() to ensure that

            # lookups are cached (see ticket #5570). This takes more code than

            # the naive ``getattr(instance, self.ct_field)``, but has better

            # performance when dealing with GFKs in loops and such.

            f = self.model._meta.get_field(self.ct_field)

            ct_id = getattr(instance, f.get_attname(), None)

        if ct_id is not None:

            ct = self.get_content_type(id=ct_id, using=instance._state.db)

            try:

                    rel_obj = ct.get_object_for_this_type(pk=getattr(instance, self.fk_field))

                rel_obj = ct.get_object_for_this_type(pk=pk_val)

            except ObjectDoesNotExist:

                pass

        setattr(instance, self.cache_attr, rel_obj)

tests/generic_relations/tests.py

+17 −0
Original line number Diff line number Diff line
@@ -555,6 +555,23 @@ id="id_generic_relations-taggeditem-content_type-object_id-1-id" /></p>""" % tag 
        with self.assertRaises(IntegrityError):

            TaggedItem.objects.create(tag="shiny", content_object=quartz)



    def test_cache_invalidation_for_content_type_id(self):

        # Create a Vegetable and Mineral with the same id.

        new_id = max(Vegetable.objects.order_by('-id')[0].id,

                     Mineral.objects.order_by('-id')[0].id) + 1

        broccoli = Vegetable.objects.create(id=new_id, name="Broccoli")

        diamond = Mineral.objects.create(id=new_id, name="Diamond", hardness=7)

        tag = TaggedItem.objects.create(content_object=broccoli, tag="yummy")

        tag.content_type = ContentType.objects.get_for_model(diamond)

        self.assertEqual(tag.content_object, diamond)



    def test_cache_invalidation_for_object_id(self):

        broccoli = Vegetable.objects.create(name="Broccoli")

        cauliflower = Vegetable.objects.create(name="Cauliflower")

        tag = TaggedItem.objects.create(content_object=broccoli, tag="yummy")

        tag.object_id = cauliflower.id

        self.assertEqual(tag.content_object, cauliflower)





class CustomWidget(forms.TextInput):

    pass