#36235: RelatedManager.all().get_or_create() does not work
-------------------------------------+-------------------------------------
Reporter: Nick Pope | Type: Bug
Status: new | Component: Database
| layer (models, ORM)
Version: dev | Severity: Normal
Keywords: get_or_create, | Triage Stage:
related, manager | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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When accessing the queryset for a related manager, `.get_or_create()` and
`.update_or_create()` lose context of the related instance.
Calling on the related manager works as expected:
{{{#!python
publisher.books.get_or_create(name="The Very Hungry Caterpillar")
}}}
This is the case that was fixed by #3121 and #23611.
But calling on the queryset causes an `IntegrityError` to be raised:
{{{#!python
publisher.books.all().get_or_create(name="The Very Hungry Caterpillar")
}}}
This can be a subtle failure that is hard to understand, especially if
`publisher.books.all()` is assigned to a variable earlier.
The challenge here is that the overridden methods on the manager set
`kwargs[self.field.name] = self.instance`.
We'd need to be able to pass this information down to the queryset. It
looks like this might already be available in `_known_related_objects`
which is set by `RelatedManager._apply_rel_filters()`, so that would be a
good starting point for investigation.
If this is something we can't fix reliably, then we should update the
admonition under
[https://docs.djangoproject.com/en/stable/ref/models/querysets/#get-or-
create .get_or_create()] in the docs and probably update
[https://docs.djangoproject.com/en/stable/ref/models/querysets/#update-or-
create .update_or_create()] to make this and other issues related to use
through `RelatedManager` more clear.
--
Ticket URL: <https://code.djangoproject.com/ticket/36235>
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