Django: Accessing method on child different child classes through common name

Question

I have an abstract base class for defining common attributes shared by different user profiles.

class Profile(models.Model):
   ...

   def has_permissions(self, project):
      ...

   class Meta:
      abstract = True

class Standard(Profile):
   ...

class Premium(Profile):
   ...

Now I would like to check the permission of a certain user (having always one distinct profile assigned) without having to know which profile he has, like

user.profile.has_permission(project)

But this does not work because the "Profile" base class is abstract. Is there a way to circumvent this problem? And is there a way to discover the name of the abstract parent class from a child object?

Thanks, Daniel

Answer 1

I am not entirely convinced that this is the best approach to take. The code is correct in the object sense of things but does not seem to fit the database view (IMHO). User will only have one profile but the database table will have links to multiple Profile tables.

How about:

1. Make profile at generic relation which can connect to any kind of Profile
2. Have a single Profile class and define permissions based on instance attribute ('premium' or 'standard')

I am curious to know what others think.

Answer 2

overwrite the auth.User method get_profile() to investigate in all Child-Profile Models Until you find it:

  class MyUser(auth.models.User):
        profile = models.OneToOneField(Profile)
        def get_profile(self):
            prof = None
            try:
                prof = Standard.objects.get(id=self.profile.pk)
            except ObjectDoesNotExist:
                prof = Premium.objects.get(id=self.profile.pk)
            return prof

now, Instead of doing this:

user.profile.has_permission(project)

you can use this:

user.get_profile().has_permission(project)

i hope that it will help you.