Question

'MODEL' has a relation with model MODEL.IN.APP, which has either not been installed or is abstract.

This error arises when I move from an explicit reference to another model in another app:

foo = models.ForeignKey(project.app.models.OtherModel)

to a quoted version of the same (to remove circular references)

foo = models.ForeignKey("project.app.models.OtherModel")

This has stung me three times now, and I’ve googled the same question asked elsewhere (without the correct answer).

Answer 1

Django’s ForeignKey takes either the Model object itself or a Django-specific string representation of the model. The string is the app-name and the model name, so the correct form is:

foo = models.ForeignKey("app.OtherModels")

not

foo = models.ForeignKey("project.app.models.OtherModels")

Using the fully qualified name in quotes gives the rather odd error message in the original question.