#14615: Related objects manager returns related objects with null FKs for
unsaved
instances
-------------------------------------+-------------------------------------
Reporter: tonnzor | Owner:
Type: Bug | Status: reopened
Component: Database layer | Version: 1.2
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: | Needs documentation: 0
Has patch: 1 | Patch needs improvement: 1
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
-------------------------------------+-------------------------------------
Changes (by lukeplant):
* needs_better_patch: 0 => 1
* stage: Design decision needed => Accepted
Comment:
According to wikipedia and this discussion:
https://groups.google.com/forum/#!msg/django-
developers/sCjjx6NmMw4/4VJ4D0vsA_kJ
...having a NULL primary key is not allowed. SQLite allows it, but doesn't
guarantee it will moving forward. Therefore, we should not program for
that edge case. Instead, we can detect unsaved instances using the
existing 'pk is None' idiom.
(If we make a decision that NULL PKs *are* allowed, there are lots of bit
of code that probably need updating, and that should be done separately -
although that seems unlikely).
The `instance._state.adding` flag was needed for the edge case of doing
uniqueness validation for explicitly set `CharField` PKs for new objects.
That is not needed here, or wanted - if the user creates a Model instance
with an explicitly set PK which corresponds to data in the database, we
expect that doing the related lookups should return the records related to
that PK e.g. we expect `User(id=1).myobject_set.all()` to return
`MyObject.objects.filter(user_id=1)`, even though the User instance was
not saved.
Apologies for the confusion my patch added.
--
Ticket URL: <https://code.djangoproject.com/ticket/14615#comment:14>
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