A ForeignKey of an abstract class can fail to validate

[rockmhoward@…]

A model with a ForeignKey relating to an abstract class fails to validate by crashing in related.py line 605.

The example models.py is attached or see: ​http://dpaste.com/66858/

The traceback from manage.py validate: ​http://dpaste.com/66860/

[rock@…]

a models.py file that fails during validation

[rock@…]

I tried adding a guard by replacing the offending line 605 as follows:

to_field = to_field
if to_field == None:

if to._meta.pk is None:

raise ValueError("The %s model does not have a primary key and therefore a ForeignKey cannot relate to it." % to_name)

to_field = to._meta.pk.name

This is not a real fix as the validate command still crashes, but the error message is a bit nicer. A real fix has to go in the validate code.

[Matthias Kestenholz]

The attached patch gives a better(?) error message for both ForeignKey and ManyToManyField, using the syntax above and also using f.e. mine = models.ManyToManyField('Attachment') (lazy loading)

[Russell Keith-Magee]

(In [8442]) Fixed #7908: Added validation checks on attempts to create ForeignKey and M2M relations with abstract classes. Thanks to Rock Howard for the report.

[Jacob]

Milestone 1.0 deleted