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Fixed #5570: generic foreign keys no longer do multiple lookups on the content type. This uses the new ctype caching bit added in [7216]. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7228 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Jacob Kaplan-Moss 2008-03-12 00:09:13 +00:00
parent cb4a018c35
commit 54d5b9ec87
1 changed files with 19 additions and 6 deletions
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23
django/contrib/contenttypes/generic.py
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@ -39,13 +39,19 @@ class GenericForeignKey(object):
# content-type/object-id fields. # content-type/object-id fields.
if self.name in kwargs: if self.name in kwargs:
value = kwargs.pop(self.name) value = kwargs.pop(self.name)
kwargs[self.ct_field] = self.get_content_type(value) kwargs[self.ct_field] = self.get_content_type(obj=value)
kwargs[self.fk_field] = value._get_pk_val() kwargs[self.fk_field] = value._get_pk_val()
def get_content_type(self, obj): def get_content_type(self, obj=None, id=None):
# Convenience function using get_model avoids a circular import when using this model # Convenience function using get_model avoids a circular import when using this model
ContentType = get_model("contenttypes", "contenttype") ContentType = get_model("contenttypes", "contenttype")
if obj:
return ContentType.objects.get_for_model(obj) return ContentType.objects.get_for_model(obj)
elif id:
return ContentType.objects.get_for_id(id)
else:
# This should never happen. I love comments like this, don't you?
raise Exception("Impossible arguments to GFK.get_content_type!")
def __get__(self, instance, instance_type=None): def __get__(self, instance, instance_type=None):
if instance is None: if instance is None:
@ -55,8 +61,15 @@ class GenericForeignKey(object):
return getattr(instance, self.cache_attr) return getattr(instance, self.cache_attr)
except AttributeError: except AttributeError:
rel_obj = None rel_obj = None
ct = getattr(instance, self.ct_field)
if ct: # 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:
ct = self.get_content_type(id=ct_id)
try: try:
rel_obj = ct.get_object_for_this_type(pk=getattr(instance, self.fk_field)) rel_obj = ct.get_object_for_this_type(pk=getattr(instance, self.fk_field))
except ObjectDoesNotExist: except ObjectDoesNotExist:
@ -71,7 +84,7 @@ class GenericForeignKey(object):
ct = None ct = None
fk = None fk = None
if value is not None: if value is not None:
ct = self.get_content_type(value) ct = self.get_content_type(obj=value)
fk = value._get_pk_val() fk = value._get_pk_val()
setattr(instance, self.ct_field, ct) setattr(instance, self.ct_field, ct)