#18094: `pre_delete` and `post_delete` signals are not correctly sent in
inheritance scenarios involving proxy models
-------------------------------------+-------------------------------------
Reporter: charettes | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.4
(models, ORM) | Keywords: model proxy multi-table
Severity: Normal | inheritance signals delete
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
This is a follow up of #18083.
Given the following models and signals (as of r17887):
{{{#!python
from django.db import models
from django.db.models import signals
class A(models.Model):
pass
class AProxy(A):
class Meta:
proxy = True
class B(A):
pass
class BFirstProxy(B):
class Meta:
proxy = True
class BSecondProxy(B):
class Meta:
proxy = True
class BFirstProxyFirstProxy(BFirstProxy):
class Meta:
proxy = True
class BFirstProxySecondProxy(BFirstProxy):
class Meta:
proxy = True
def pre_delete(sender, instance, **kwargs):
print "`pre_delete` %r %r" % (sender, instance)
signals.pre_delete.connect(pre_delete, A)
signals.pre_delete.connect(pre_delete, AProxy)
signals.pre_delete.connect(pre_delete, B)
signals.pre_delete.connect(pre_delete, BFirstProxy)
signals.pre_delete.connect(pre_delete, BSecondProxy)
signals.pre_delete.connect(pre_delete, BFirstProxyFirstProxy)
signals.pre_delete.connect(pre_delete, BFirstProxySecondProxy)
def post_delete(sender, instance, **kwargs):
return # Avoid dispatching for output clarity
print "`post_delete` %r %r" % (sender, instance)
signals.post_delete.connect(post_delete, A)
signals.post_delete.connect(post_delete, AProxy)
signals.post_delete.connect(post_delete, B)
signals.post_delete.connect(post_delete, BFirstProxy)
signals.post_delete.connect(post_delete, BSecondProxy)
signals.post_delete.connect(post_delete, BFirstProxyFirstProxy)
signals.post_delete.connect(post_delete, BFirstProxySecondProxy)
}}}
`pre_delete` and `post_delete` signals dispatching depends on the deletion
source and don't propagate up the proxy chain nor to the proxy leaves.
i.e. (here `post_delete`'s dispatching should behave the same)
== Basic model proxy ==
'''Actual behaviours'''
{{{
>>> A.objects.create().delete()
`pre_delete` <class 'proxy_signals.models.A'> <A: A object>
>>> AProxy.objects.create().delete()
`pre_delete` <class 'proxy_signals.models.AProxy'> <AProxy: AProxy object>
}}}
'''Expected behaviour in both cases'''
{{{
`pre_delete` <class 'proxy_signals.models.AProxy'> <AProxy: AProxy object>
`pre_delete` <class 'proxy_signals.models.A'> <A: A object>
}}}
== Multi-table inheritance model proxy ==
'''Actual behaviours'''
{{{
>>> B.objects.create().delete()
`pre_delete` <class 'proxy_signals.models.B'> <B: B object>
`pre_delete` <class 'proxy_signals.models.A'> <A: A object>
>>> BFirstProxy.objects.create().delete()
`pre_delete` <class 'proxy_signals.models.BFirstProxy'> <BFirstProxy:
BFirstProxy object>
`pre_delete` <class 'proxy_signals.models.A'> <A: A object>
>>> BSecondProxy.objects.create().delete()
`pre_delete` <class 'proxy_signals.models.BSecondProxy'> <BSecondProxy:
BSecondProxy object>
`pre_delete` <class 'proxy_signals.models.A'> <A: A object>
>>> BFirstProxyFirstProxy.objects.create().delete()
`pre_delete` <class 'proxy_signals.models.BFirstProxyFirstProxy'>
<BFirstProxyFirstProxy: BFirstProxyFirstProxy object>
`pre_delete` <class 'proxy_signals.models.A'> <A: A object>
>>> BFirstProxySecondProxy.objects.create().delete()
`pre_delete` <class 'proxy_signals.models.BFirstProxySecondProxy'>
<BFirstProxySecondProxy: BFirstProxySecondProxy object>
`pre_delete` <class 'proxy_signals.models.A'> <A: A object>
}}}
'''Expected behaviour in all cases'''
{{{
`pre_delete` <class 'proxy_signals.models.BFirstProxyFirstProxy'>
<BFirstProxyFirstProxy: BFirstProxyFirstProxy object>
`pre_delete` <class 'proxy_signals.models.BFirstProxySecondProxy'>
<BFirstProxySecondProxy: BFirstProxySecondProxy object>
`pre_delete` <class 'proxy_signals.models.BFirstProxy'> <BFirstProxy:
BFirstProxy object>
`pre_delete` <class 'proxy_signals.models.BSecondProxy'> <BSecondProxy:
BSecondProxy object>
`pre_delete` <class 'proxy_signals.models.B'> <B: B object>
`pre_delete` <class 'proxy_signals.models.AProxy'> <AProxy: AProxy object>
`pre_delete` <class 'proxy_signals.models.A'> <A: A object>
}}}
What needs to be fixed:
* Dispatch the `concrete_model` signals even when the source is an
instance of a proxy
* Dispatch the signals for all proxy of concrete models involved in the
deletion
* Preserve the expected dispatching order
Failing integrated TestCase to come.
--
Ticket URL: <https://code.djangoproject.com/ticket/18094>
Django <https://code.djangoproject.com/>
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