Limit possible values for ForeignKey to a subset of models

Question

I have the following model:

class SOA(models.Model):
    adviser = models.ForeignKey(User)
    ...

The adviser can not be any user, but a user which satisfies certain requirements (for example, a user which belongs to a certain group). This is relevant for example when dealing with forms: a dropdown to select the adviser shows me all users in the system, but I want to filter that and only show users which are actually advisers (which is defined, in this case, by belonging to an advisers group)

Is it possible to handle this kind of constraint at the model level? Or maybe when populating the select box in the form?

Answer 1

You can use limit_choices_to init argument of ForeignKey class. For example:

adviser = models.ForeignKey(User, limit_choices_to={'is_staff': True})

For more complex queries, you can use Q objects:

..., limit_choices_to=Q(share_holder=True) | Q(distributor=True)