#34207: Incorrect SQL query when adding a ManyToMany related object with a
"through" table prevents adding a new relationship if the new relationship
is identical except for a different value for "through_defaults"
-------------------------------------+-------------------------------------
Reporter: Credentive | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: 4.1
(models, ORM) |
Severity: Normal | Resolution: duplicate
Keywords: ManyToManyField | Triage Stage:
through | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Credentive):
Your example documentation strongly suggests otherwise (while cautioning
about "remove"), see here:
https://docs.djangoproject.com/en/4.1/topics/db/models/#extra-fields-on-
many-to-many-relationships
{{{
>>> ringo = Person.objects.create(name="Ringo Starr")
>>> paul = Person.objects.create(name="Paul McCartney")
>>> beatles = Group.objects.create(name="The Beatles")
>>> m1 = Membership(person=ringo, group=beatles,
... date_joined=date(1962, 8, 16),
... invite_reason="Needed a new drummer.")
>>> m1.save()
>>> beatles.members.all()
<QuerySet [<Person: Ringo Starr>]>
>>> ringo.group_set.all()
<QuerySet [<Group: The Beatles>]>
>>> m2 = Membership.objects.create(person=paul, group=beatles,
... date_joined=date(1960, 8, 1),
... invite_reason="Wanted to form a band.")
>>> beatles.members.all()
<QuerySet [<Person: Ringo Starr>, <Person: Paul McCartney>]>
>>> Membership.objects.create(person=ringo, group=beatles,
... date_joined=date(1968, 9, 4),
... invite_reason="You've been gone for a month and we miss you.")
>>> beatles.members.all()
<QuerySet [<Person: Ringo Starr>, <Person: Paul McCartney>, <Person: Ringo
Starr>]>
>>> # This deletes both of the intermediate model instances for Ringo
Starr
>>> beatles.members.remove(ringo)
>>> beatles.members.all()
<QuerySet [<Person: Paul McCartney>]>
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/34207#comment:2>
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