#18094: `pre_delete` and `post_delete` signals are not correctly sent in
inheritance scenarios involving proxy models
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Reporter: charettes | Owner: charettes
Type: Bug | Status: assigned
Component: Database layer | Version: 1.4
(models, ORM) | Resolution:
Severity: Normal | Triage Stage:
Keywords: model proxy multi- | Unreviewed
table inheritance signals delete | Needs documentation: 0
Has patch: 0 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by akaariai):
Making init signals consistent isn't likely for performance reasons - in
fact it might make sense to replace them with init hooks. That would fit
the use case of the signals, and currently the init signals can make model
init around 2x slower in the not so uncommon case that model init signals
are defined for some __other__ model in the project - not necessarily the
one being initialized.
Altering save signals to fire for each parent class (proxy or not) would
make sense. Assuming Foo and !FooBar(Foo) models, it is more than likely
that if you have a signal for Foo that then you have attached the same
signal for !FooBar too. Because you want to catch "Foo saved" when !FooBar
is saved - the exact issue we are trying to fix here. So, fixing the
signals in the way suggested in this ticket removes the need of attaching
the same signal multiple times but at same time __is__ going to break
existing usage. For how many users is a different question.
I am not sure if the above backwards compatibility issue is meaningful for
delete signals, so if consistency is not possible then fixing just delete
signals makes sense.
All in all, maybe the consistency issue should be discussed at django-
developers?
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Ticket URL: <https://code.djangoproject.com/ticket/18094#comment:8>
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