RenameModel does not not change ForeignKey with related_name='+'

[Alexander Schrijver]

When you create a ForeignKey with a related_name='+' to a second model, and you rename the second model, the model which is referred in the ForeignKey is not updated. I've created a updated OperationTests.test_rename_model test to show this (PR: ​https://github.com/django/django/pull/8146). This only affects 1.10, this issue seems to be fixed in 1.11.

[Simon Charette]

I assume this was fixed by the RenameModel refactor in #27310 as we don't rely on related objects anymore (which can be missing when related_name ends with '+').

I'm not sure this is worth fixing at this point in the 1.10 release cycle.

[Tim Graham]

I agree with Simon.

[Alexander Schrijver]

As a workaround you can do is: before the RenameModel with a AlterField set the ForeignKey's related_name to some temporary value, and then set it back to '+' when you've done the RenameModel. e.g.:

migrations.AlterField(
    model_name='SomeModel',
    name='some_field',
    field=models.ForeignKey(... related_name='xxx', to='app.OtherModel'),
),
migrations.RenameModel('OtherModel', 'OtherModel2'),
migrations.AlterField(
    model_name='SomeModel',
    name='some_field',
    field=models.ForeignKey(... related_name='+', to='app.OtherModel2'),
),