#25027: two relations on the same model with same related_name break the model
-------------------------------+--------------------------------------
Reporter: karyon | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 1.8
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by karyon:
Old description:
> consider the following models:
> {{{
> class UserProfile(models.Model):
> pass
>
> class Course(models.Model):
> participants = models.ManyToManyField(UserProfile,
> related_name='foo')
>
> class Document(models.Model):
> last_modified_user = models.ForeignKey(UserProfile,
> related_name='foo')
> }}}
>
> and the following query:
> {{{
> >>> str(Course.objects.first().participants.all().query)
> 'SELECT "testapp_userprofile"."id" FROM "testapp_userprofile" INNER JOIN
> "testapp_document" ON ( "testapp_userprofile"."id" =
> "testapp_document"."last_modified_user_id" ) WHERE
> "testapp_document"."id" = 1'
> }}}
>
> the join doesn't make any sense to me. it makes both assertions in the
> following test fail:
>
> {{{
> def test_related_name(self):
> user = UserProfile.objects.create()
> course = Course.objects.create()
> course.participants = UserProfile.objects.all()
> self.assertEqual(course.participants.count(), 1)
> self.assertEqual(list(course.participants.all()), [user])
> }}}
>
> changing the related name in one of the models to something else fixes
> this.
>
> i would have expected to get some warning that i'm using the same related
> name on the same model. especially i expected this to not break when i'm
> not even using the related name in the test.
>
> this also breaks when using '+' as related name. in this case, i would
> expect everything to just work.
New description:
consider the following models:
{{{
class UserProfile(models.Model):
pass
class Course(models.Model):
participants = models.ManyToManyField(UserProfile, related_name='+')
class Document(models.Model):
last_modified_user = models.ForeignKey(UserProfile, related_name='+')
}}}
and the following query:
{{{
>>> str(Course.objects.first().participants.all().query)
'SELECT "testapp_userprofile"."id" FROM "testapp_userprofile" INNER JOIN
"testapp_document" ON ( "testapp_userprofile"."id" =
"testapp_document"."last_modified_user_id" ) WHERE "testapp_document"."id"
= 1'
}}}
the join doesn't make any sense to me. it makes both assertions in the
following test fail:
{{{
def test_related_name(self):
user = UserProfile.objects.create()
course = Course.objects.create()
course.participants = UserProfile.objects.all()
self.assertEqual(course.participants.count(), 1)
self.assertEqual(list(course.participants.all()), [user])
}}}
changing the related name in one of the models to something else fixes
this.
if using a related name other than '+', the test still fails as before and
the check command does not complain either, but at least makemigrations
will spot the mistake.
--
--
Ticket URL: <https://code.djangoproject.com/ticket/25027#comment:2>
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