#26186: When extending from abstract model, ForeignKey points to wrong
application
-------------------------------------+-------------------------------------
Reporter: skyjur | Owner: charettes
Type: Bug | Status: assigned
Component: Database layer | Version: 1.9
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by charettes):
* status: new => assigned
* owner: nobody => charettes
* severity: Normal => Release blocker
* stage: Unreviewed => Accepted
Comment:
Well I stand corrected. It looks like the reported behavior is possible as
long as the application containing the abstract module is not yet
imported.
Here's what happens on '''Django 1.8'''.
The `b` application is imported by the app loading mechanism and triggers
and the import of `a.abstract`. At this point the abstract models are not
bound to any application and thus the `AbstractModel2.model1` field is not
resolved to any model which allows the `b.Model2.model1` field to resolves
to `b.Model1`. When the `a` application is loaded the abstract models are
bound to it (because they are defined in a `a` submodule) and thus
`a.Model2` automatically resolves to `a.Model1`.
In this case if the `a` application is loaded before the `b` application
`b.Model2` will point to `a.Model1` because the abstract models were bound
to the `a` application when `b.models` will import `a.abstract` (which was
imported by `a.models` first).
Here's what happen before #25858 was fixed ('''1.9, 1.9.1'''):
App relative lazy relationships defined on abstract models were never
resolved thus the behavior described above if the `b` application appeared
before the `a` one on Django `1.8` was always present and not dependent on
`ÌNSTALLED_APPS` ordering.
Here's what happen since #25858 is fixed ('''1.9.2''' , '''master'''):
It's not possible anymore as app relative lazy relationships defined on
abstract models are bound to the application in which they are defined.
I'll take this to the ML again to gather feedback but I'm inclined to
close this as ''wontfix'' because the behavior was only achievable in 1.8
through import side effects.
--
Ticket URL: <https://code.djangoproject.com/ticket/26186#comment:8>
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