Inherited ManyToMany.all() empty with multiple inherited models of same name from abstract one

[Gereon Kremer]

Please see #24156 first!

The issue described there still persists if the derived model classes have the same class name (spread across different apps).
I understand this to be a weird model design at least, but found it to be reasonable for my current project.

I'd suggest to either use the fully qualified class name (i.e. app.model_class instead of model_class) to build the related_name, or at least note in the documentation that models with identical names can be a problem with inheritance.

[Carlton Gibson]

Hi Gereon — are you able to upload a sample project reproducing this?

[Gereon Kremer]

Example project showcasing the issue.

[Gereon Kremer]

Sure, see the new attachment.
Running ./manage.py makemigrations yields

SystemCheckError: System check identified some issues:

ERRORS:
appA.Stuff.owners: (fields.E305) Reverse query name for 'Stuff.owners' clashes with reverse query name for 'Stuff.owners'.
        HINT: Add or change a related_name argument to the definition for 'Stuff.owners' or 'Stuff.owners'.
appB.Stuff.owners: (fields.E305) Reverse query name for 'Stuff.owners' clashes with reverse query name for 'Stuff.owners'.
        HINT: Add or change a related_name argument to the definition for 'Stuff.owners' or 'Stuff.owners'.

[Carlton Gibson]

OK, thanks. So the system check error that spells out the problem:

$ ./manage.py makemigrations
SystemCheckError: System check identified some issues:

ERRORS:
app1.Child.field1: (fields.E305) Reverse query name for 'Child.field1' clashes with reverse query name for 'Child.field1'.
	HINT: Add or change a related_name argument to the definition for 'Child.field1' or 'Child.field1'.
app2.Child.field1: (fields.E305) Reverse query name for 'Child.field1' clashes with reverse query name for 'Child.field1'.
	HINT: Add or change a related_name argument to the definition for 'Child.field1' or 'Child.field1'.

See the docs section: ​Be careful with related_name and related_query_name. Specify something like related_name="%(app_label)s_%(class)s_related" on the ManyToManyField on the abstract model.

[Gereon Kremer]

Oh sorry, I did not see this particular section...