[Django] #25505: Incomplete relation_tree for inherited proxied Models.
Django
-------------------------------------+-------------------------------------
Reporter: jelko | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.8
(models, ORM) | Keywords: models, meta, deletion,
Severity: Normal | relation, inheritance
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
`Options._populate_directed_relation_graph` produces an incomplete
`Options._relation_tree` for Models that have set `Meta.Proxy = True`.
Consider this setup:
BaseModel(models.Model) -> ProxyModel(BaseModel) [with Proxy = True] ->
ChildModel(ProxyModel)
In this case the OneToOne relation from ProxyModel to ChildModel is not
included in the proxymodel's `_meta._relation_tree`.
This is caused because `Options._populate_directed_relation_graph`
collects the relations by calling `model._meta._get_fields(reverse=False,
include_parents=False)`. Therefore the parent, in this case the ProxyModel
is not included.
This results in some unwanted situations. If you call `delete()` on a
ProxyModel, the BaseModel gets deleted, but the ChildModel instance stays
in the database and becomes orphaned.
Have a look at the attached models.py to replicate the setup. Compare the
behavior of `delete()` for instances of `ChipShop` and `IndianRestaurant`,
to see the problem.
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Ticket URL: <https://code.djangoproject.com/ticket/25505>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
Django
Reporter: jelko | Owner: nobody
Type: Bug | Status: new
Severity: Normal | Resolution:
Keywords: models, meta, deletion, relation, | Triage Stage:
inheritance | Unreviewed
Has patch: 0 | Easy pickings: 0
UI/UX: 0 |
Changes (by jelko):
* Attachment "models.py" added.
Django
-------------------------------------+-------------------------------------
Reporter: jelko | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.8
(models, ORM) |
Keywords: models, meta, | Triage Stage:
deletion, relation, inheritance | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
* needs_better_patch: => 0
* needs_tests: => 0
* needs_docs: => 0
Comment:
Hi jelko,
Could have a look at the [https://github.com/django/django/pull/5378
patch] proposed for #18012 and see if that fixes the reported issue. I
haven't tried it myself but from the description you provided it looks
like the same scenario.
--
Ticket URL: <https://code.djangoproject.com/ticket/25505#comment:1>
Django
-------------------------------------+-------------------------------------
Reporter: jelko | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.8
(models, ORM) |
Keywords: models, meta, | Triage Stage: Accepted
deletion, relation, inheritance |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
* cc: charettes (added)
* stage: Unreviewed => Accepted
Comment:
It looks like this is another can of worms.
The patch proposed for #18012 doesn't fix the reported issue which I
managed to reproduce with the attached test case.
--
Ticket URL: <https://code.djangoproject.com/ticket/25505#comment:2>
Django
-------------------------------------+-------------------------------------
Reporter: jelko | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.8
(models, ORM) |
Keywords: models, meta, | Triage Stage: Accepted
deletion, relation, inheritance |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
* Attachment "25505-reproduced-issue.diff" added.
Integrated test case
Django
-------------------------------------+-------------------------------------
Reporter: jelko | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.8
(models, ORM) |
Keywords: models, meta, | Triage Stage: Accepted
deletion, relation, inheritance |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by charettes):
Note that the test case uses `exists()` instead of `get()` because the
latter won't return any results and hide the issue because of deferred
constraint checks in the transaction wrapping the test case.
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Ticket URL: <https://code.djangoproject.com/ticket/25505#comment:3>
Django
-------------------------------------+-------------------------------------
Reporter: jelko | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.8
(models, ORM) |
Keywords: models, meta, | Triage Stage: Accepted
deletion, relation, inheritance |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by charettes):
This looks related to #23076.
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Ticket URL: <https://code.djangoproject.com/ticket/25505#comment:4>
Django
-------------------------------------+-------------------------------------
Reporter: jelko | Owner: nobody
Component: Database layer | Version: 1.8
(models, ORM) |
Keywords: models, meta, | Triage Stage: Accepted
deletion, relation, inheritance |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
* status: new => closed
* resolution: => fixed
Comment:
In [changeset:"211486f3ab5602cdc332f03cd03fad3cb929d154" 211486f3]:
{{{
#!CommitTicketReference repository=""
revision="211486f3ab5602cdc332f03cd03fad3cb929d154"
Fixed #23076, #25505 -- Fixed deletion of intermediate proxy models.
Thanks to James Murty for his work on an alternate patch.
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/25505#comment:5>