Opened 6 hours ago

Last modified 5 hours ago

#35890 new Bug

pre_save field in parent models are not called during update in update_or_create — at Initial Version

Reported by: Gagaro Owned by:
Component: Database layer (models, ORM) Version: dev
Severity: Normal Keywords:
Cc: Gagaro Triage Stage: Accepted
Has patch: yes Needs documentation: no
Needs tests: no Patch needs improvement: yes
Easy pickings: no UI/UX: no

Description

With the following models:

class Parent(models.Model):
    modified_at = models.DateTimeField(auto_now=True)


class Child(Parent):
    modified_at_child = models.DateTimeField(auto_now=True)

When calling update_or_create, the pre_save of the modified_at field is not called, and the field is not updated:

# Create

>>> instance, _ = Child.objects.update_or_create(pk=1)
>>> instance.modified_at
datetime.datetime(2024, 11, 6, 14, 1, 11, 52881, tzinfo=datetime.timezone.utc)
>>> instance.modified_at_child
datetime.datetime(2024, 11, 6, 14, 1, 11, 54363, tzinfo=datetime.timezone.utc)


# Update

>>> instance, _ = Child.objects.update_or_create(pk=1)
>>> instance.modified_at
datetime.datetime(2024, 11, 6, 14, 1, 11, 52881, tzinfo=datetime.timezone.utc)
>>> instance.modified_at_child
datetime.datetime(2024, 11, 6, 14, 1, 21, 517245, tzinfo=datetime.timezone.utc)

The regression seems to have happened in https://github.com/django/django/commit/6cc0f22a73970dd7c0d29d4d8d2ff9e1cc862b30

Using self.model._meta.concrete_fields instead of self.model._meta.local_concrete_fields seems to solve the issue, but I don't know the internal API well enough to understand all of the implications.

I'm also preparing a PR with a unit test and the fix, I'll update this ticket when it will be ready.

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