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

This commit is contained in:
Michal Petrucha 2016-05-01 18:32:40 +02:00 committed by Tim Graham
parent 7ec330eeb9
commit b9f8635f58
2 changed files with 41 additions and 15 deletions

View File

@ -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)
@ -217,26 +217,35 @@ 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
# 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))
except ObjectDoesNotExist:
pass
setattr(instance, self.cache_attr, rel_obj)
if rel_obj is not None:
return rel_obj
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=pk_val)
except ObjectDoesNotExist:
pass
setattr(instance, self.cache_attr, rel_obj)
return rel_obj
def __set__(self, instance, value):
ct = None
fk = None

View File

@ -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