[Django] #21559: Generic relations regression in Django 1.6
Django
----------------------------------------------+--------------------
Reporter: khoobks@… | Owner: nobody
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: 1.6
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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Please see the code below for a demonstration of the regression.
== The Model ==
{{{
from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic
class TaggedItem(models.Model):
tag = models.SlugField()
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
content_object = generic.GenericForeignKey('content_type',
'object_id')
# On Python 3: def __str__(self):
def __unicode__(self):
return self.tag
class Bookmark(models.Model):
url = models.URLField()
tags = generic.GenericRelation(TaggedItem)
}}}
== The Setup ==
{{{
from test_app.models import *
b = Bookmark(url='https://www.djangoproject.com/')
b.save()
t1 = TaggedItem(content_object=b, tag='django')
t1.save()
t2 = TaggedItem(content_object=b, tag='python')
t2.save()
}}}
== Django 1.5 ==
{{{
Python 2.7.3 (default, Apr 10 2012, 23:31:26) [MSC v.1500 32 bit (Intel)]
on win32
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> import django
>>> from test_app.models import *
>>> django.VERSION
(1, 5, 5, 'final', 0)
>>> TaggedItem.objects.filter(bookmark__url__icontains='django')
[<TaggedItem: django>, <TaggedItem: python>]
>>>
}}}
== Django 1.6 ==
{{{
Python 2.7.3 (default, Apr 10 2012, 23:31:26) [MSC v.1500 32 bit (Intel)]
on win32
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>>
>>> import django
>>> from test_app.models import *
>>> django.VERSION
(1, 6, 0, 'final', 0)
>>> TaggedItem.objects.filter(bookmark__url__icontains='django')
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "C:\workspace\django_generic_relationship\django16\lib\site-
packages\django\db\models\manager.py", line 163, in f
ilter
return self.get_queryset().filter(*args, **kwargs)
File "C:\workspace\django_generic_relationship\django16\lib\site-
packages\django\db\models\query.py", line 590, in fil
ter
return self._filter_or_exclude(False, *args, **kwargs)
File "C:\workspace\django_generic_relationship\django16\lib\site-
packages\django\db\models\query.py", line 608, in _fi
lter_or_exclude
clone.query.add_q(Q(*args, **kwargs))
File "C:\workspace\django_generic_relationship\django16\lib\site-
packages\django\db\models\sql\query.py", line 1198, i
n add_q
clause = self._add_q(where_part, used_aliases)
File "C:\workspace\django_generic_relationship\django16\lib\site-
packages\django\db\models\sql\query.py", line 1232, i
n _add_q
current_negated=current_negated)
File "C:\workspace\django_generic_relationship\django16\lib\site-
packages\django\db\models\sql\query.py", line 1100, i
n build_filter
allow_explicit_fk=True)
File "C:\workspace\django_generic_relationship\django16\lib\site-
packages\django\db\models\sql\query.py", line 1351, i
n setup_joins
names, opts, allow_many, allow_explicit_fk)
File "C:\workspace\django_generic_relationship\django16\lib\site-
packages\django\db\models\sql\query.py", line 1274, i
n names_to_path
"Choices are: %s" % (name, ", ".join(available)))
FieldError: Cannot resolve keyword 'bookmark' into field. Choices are:
content_type, id, object_id, tag
>>>
}}}
I would have expected that the same code should work the same way between
Django 1.5 and 1.6.
--
Ticket URL: <https://code.djangoproject.com/ticket/21559>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
Django
Reporter: khoobks@… | Owner: nobody
Type: Bug | Status: new
(models, ORM) | Resolution:
Severity: Release blocker | Triage Stage: Accepted
Keywords: | Needs documentation: 0
Has patch: 0 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
-------------------------------------+-------------------------------------
Changes (by akaariai):
* needs_docs: => 0
* needs_better_patch: => 0
* severity: Normal => Release blocker
* needs_tests: => 0
* stage: Unreviewed => Accepted
Comment:
I can confirm that the queries work differently. However, the 1.5 version
didn't work correctly at all. Using generic_relations test models:
{{{
a = Animal.objects.create(common_name='foo', latin_name='bar')
Vegetable.objects.create(name='foo', pk=a.pk)
TaggedItem.objects.create(content_object=a)
print TaggedItem.objects.filter(vegetable__name__icontains='foo')
print
TaggedItem.objects.filter(vegetable__name__icontains='foo').query
}}}
The output is:
{{{
[<TaggedItem: >]
SELECT ...
FROM "generic_relations_taggeditem"
INNER JOIN "generic_relations_taggeditem" T2 ON
("generic_relations_taggeditem"."id" = T2."id")
INNER JOIN "generic_relations_vegetable" ON (T2."object_id" =
"generic_relations_vegetable"."id")
INNER JOIN "django_content_type" ON
("generic_relations_taggeditem"."content_type_id" =
"django_content_type"."id")
WHERE "generic_relations_vegetable"."name" LIKE %foo% ESCAPE '\'
ORDER BY "generic_relations_taggeditem"."tag" ASC,
"django_content_type"."name" ASC
}}}
Note the lack of any constraint on the content type. For this reason a
vegetable is found even if there is no relationship to any vegetable at
all.
The query construct used wasn't documented (at least I can't find a
reference) and is completely untested. I am confident that having the
query produce any results at all is just an accident caused by
implementation details.
I think I'll just have to document that such queries do not work any more,
and that they never actually produced any correct results. The other
option is to make this construct work properly in 1.6, but I believe that
will be a lot of work and could require changes that break popular 3rd
party software (django-taggit comes to mind here). It would likely be
possible to make the query construct work like in 1.5, too, but loud
failure seems a lot better than a silently returning wrong data.
Marking as release blocker, docs need updating at least.
--
Ticket URL: <https://code.djangoproject.com/ticket/21559#comment:1>
Django
Reporter: khoobks@… | Owner: nobody
Type: Bug | Status: new
(models, ORM) | Resolution:
Severity: Release blocker | Triage Stage: Accepted
Keywords: | Needs documentation: 0
Has patch: 0 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by pschmidt@…):
For anyone else who had a stack of production code depending on this
apparently hidden / undocumented feature, I got around it by rewriting
with subqueries, something like:
{{{
bookmarks = BookMark.objects.filter(url__icontains='django')
content_type = ContentType.objects.get(app_label='...', model='bookmark')
TaggedItem.objects.filter(object_id__in=bookmarks,
content_type=content_type)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/21559#comment:2>
Django
Reporter: khoobks@… | Owner: nobody
Type: Bug | Status: new
(models, ORM) | Resolution:
Keywords: | Needs documentation: 0
Has patch: 0 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
-------------------------------------+-------------------------------------
* severity: Release blocker => Normal
Comment:
Given the akaariai's explanation, I don't think this is a release blocker.
Something that didn't work still doesn't work. This shouldn't prevent 1.7
from moving forwards.
--
Ticket URL: <https://code.djangoproject.com/ticket/21559#comment:3>
Django
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Reporter: khoobks@… | Owner: nobody
Type: Bug | Status: closed
Component: contrib.contenttypes | Version: 1.6
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Changes (by timgraham):
* status: new => closed
* component: Database layer (models, ORM) => contrib.contenttypes
* resolution: => fixed
Comment:
I'll mark this as fixed since #22207 added support for querying the
reverse generic relation using the `related_query_name` option of
`GenericRelation`.
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Ticket URL: <https://code.djangoproject.com/ticket/21559#comment:4>