#34796: Deleting child table does not delete rows in parent table when using
multi-
table inheritance
-------------------------------------+-------------------------------------
Reporter: Stephen Finucane | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 4.2
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Stephen Finucane:
Old description:
> I am aware that we don't use database-level cascades (ticket:21961) but I
> expected this to be implemented by Django in Python, given the docs
> (https://docs.djangoproject.com/en/4.2/topics/db/models/#multi-table-
> inheritance) say that the automatically-created `OneToOneField` on the
> child model will have `on_delete=models.CASCADE`.
>
> {{{
> place_ptr = models.OneToOneField(
> Place,
> on_delete=models.CASCADE,
> parent_link=True,
> primary_key=True,
> )
> }}}
>
> I have a minimal reproducer which can be found at
> https://github.com/stephenfin/django-bug-34796. In summary though, you
> simply need to create a table using multi-table inheritance and then
> delete that table. While the child table will be deleted, the
> corresponding rows in the parent table will remain.
New description:
If you have a child model that depends on a parent model via multi-table
inheritance, then deleting the child will not delete rows in the parent
model's table.
I am aware that we don't use database-level cascades (ticket:21961) but I
expected this to be implemented by Django in Python, given the docs
(https://docs.djangoproject.com/en/4.2/topics/db/models/#multi-table-
inheritance) say that the automatically-created `OneToOneField` on the
child model will have `on_delete=models.CASCADE`.
{{{
place_ptr = models.OneToOneField(
Place,
on_delete=models.CASCADE,
parent_link=True,
primary_key=True,
)
}}}
I have a minimal reproducer which can be found at
https://github.com/stephenfin/django-bug-34796. In summary though, you
simply need to create a table using multi-table inheritance and then
delete that table. While the child table will be deleted, the
corresponding rows in the parent table will remain.
--
--
Ticket URL: <https://code.djangoproject.com/ticket/34796#comment:3>
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