Add a `for_concrete_model` kwarg to `ContentTypeManager.get_for_models?`

[Simon Charette]

ContentTypeManager.get_for_models? always return the ContentType of the concrete model.

As highlighted in #17648 and #11154 there is cases that would benefit from the option of retrieving the ContentType of proxy models.

However changing ContentTypeManager.get_for_model? to return the ContentType of proxy models would be backward incompatible.

I suggest adding a for_concrete_model=True kwarg to ContentTypeManager.get_for_models? which defaults to <=1.4 behaviour.

Pull request to come.

[Simon Charette]

Looking at get_for_models implementation there doesn't seems to be way to add this flag while maintaining backward compatiblity since models are passed as *args... We can rely on kwargs but maybe we could change signatures to get models from *args[0] say def get_for_models(self, models, for_concrete_models=True) and raise a deprecation warning if the old signature is used?

[Simon Charette]

Added ​pull request with tests and docs.

[Anssi Kääriäinen <akaariai@…>]

In [b6d533af4d03f27ea957baa5fd70f7d0b942ef9a]:

Fixed #18399 – Added a way to get ContentTypes for proxy models

Added kwargs for_concrete_model and for_concrete_models to ContentType
methods get_for_model() and get_for_models(). By setting the flag to
False, it is possible to get the contenttype for proxy models.

[Omer Katz]

Does this resolve #11154 in any way?

[Simon Charette]

This ticket adds a feature required to solve #11154.