I have two classes System and Station which inherit from Base. The Base class has a foreign key to Group and Station has a foreign key to System.

I am trying to place a 'limit_choices_to' constraint on the latter FK, so that the related System has to be from the same Group as the Station.

Here's a snippet of the models.py

class Base(models.Model):
    group = models.ForeignKey(Group)

class System(Base):
    ...

class Station(Base):
    system_info = models.ForeignKey(System, limit_choices_to={'group': 'self.group'})

I've tried a number of ideas, including what is above, but no luck. Any help will be much appreciated!