#13839: select_related caches None for non-existent objects in reverse
one-to-one
relations
-----------------------------+----------------------------------------------
Reporter: shauncutts | Owner:
Status: new | Milestone:
Component: ORM aggregation | Version: 1.2
Keywords: | Stage: Unreviewed
Has_patch: 0 |
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Suppose we have the following:
{{{
class AM( models.Manager ):
def get_query_set( self ):
q = super( AM, self ).get_query_set()
q = q.select_related( 'b' )
return q
class A( models.Model ):
objects = AM()
pass
class B( A ):
pass
}}}
Then when we create an A, and retrieve via the manager we have:
{{{
>>> A.objects.create()
<A: A object>
>>> a = A.objects.all()[ 0 ]
>>> a.__dict__
{'_b_cache': None,
'_state': <django.db.models.base.ModelState object at 0x1fc6930>,
'id': 2}
}}}
This causes problems, as {{{ a.b }}} yields None rather than triggering
ObjectDoesNotExist, which causes problems -- e.g.:
{{{
>>> a.delete()
/Users/shauncutts/dev/django/db/models/base.pyc in delete(self, using)
645 # Find all the objects than need to be deleted.
646 seen_objs = CollectedObjects()
--> 647 self._collect_sub_objects(seen_objs)
648
649 # Actually delete the objects.
/Users/shauncutts/dev/django/db/models/base.pyc in
_collect_sub_objects(self, seen_objs, parent, nullable)
--> 580 sub_obj._collect_sub_objects(seen_objs, self,
related.field.null)
581 else:
582 # To make sure we can access all elements, we
can't use the
AttributeError: 'NoneType' object has no attribute '_collect_sub_objects'
}}}
--
Ticket URL: <http://code.djangoproject.com/ticket/13839>
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