Django: How do you access a model's instance from inside a manager?

Question

class SupercalifragilisticexpialidociousManager(models.Manager):
    # Sorry, I'm sick of Foo and Spam for now.
    def get_query_set(self, account=None):
        return super(SupercalifragilisticexpialidociousManager,
                     self).get_query_set().filter(uncle=model_thats_using_this_manager_instance.uncle)

The magic I'm looking for is the "uncle=model_thats_using_this_manager_instance.uncle". It seems like I should be able to do this somehow. I know I could say self.model to get the model, but how to get the instance?

Answer 1

It doesn't make sense to ask for an instance when you're using a manager. Managers are class-level attributes - if you try and do foo.objects.all() where foo is an instance of Supercalifragilisticexpialidocious, you will explicitly get an error:

AttributeError: Manager isn't accessible via Supercalifragilisticexpialidocious instances

Answer 2

AFAK you cannot access the model from inside a manager. It doesn't make sense as managers operate on the whole table.

You should do something like this in the model:

class Model(models.Model):
    # some attributes here
    def getAllRelativesWithSameUncle(self):
        return self.objects.filter(uncle = self.uncle)

or in the manager:

class SupercalifragilisticexpialidociousManager(models.Manager):
    def getSameRelativesFor(self, model_instance):
        return self.get_query_set().filter(uncle=model_instance.uncle)