Can the model manager access the Meta attribute of their models (`Meta.unique_together`)?

Here is my attempt at a generic manager of the natural key model. It's like docs , except that it tries (unsuccessfully) to determine the field names of the natural key from the Meta.unique_together attribute.

class NaturalKeyModelManager(Manager):

    def get_by_natural_key(self, *args):
        field_dict = {}
        for i, k in enumerate(self.model.Meta.unique_together[0]):
            field_dict[k] = args[i]
        return self.get(**field_dict)

If I insert debug printing just before the for loop, as follows:

print dir(self.model.Meta)

it does not list the unqiue_together attribute:

['__doc__', '__module__', 'abstract']

The “abstract” bit bothered me, but another debugging fingerprint shows that the model I'm trying to manipulate natural keys with is not abstract:

>>> print self.model.Meta.abstract
False

I mix a lot of abstract base classes. Could this be a problem?

class MixedModel(NamedModel, TimeStampedModel, VersionedModel, Model):
    objects = NaturalKeyModelManager()

    class Meta:
        unique_together = (('name', 'version',),)

For completeness, here is one of the mixins:

class TimeStampedModel(Model):
    created = DateTimeField(_("Created"),     auto_now_add=True, null=True, editable=False)
    updated = DateTimeField(_("Updated"),     auto_now=True,     null=True, editable=True)

    class Meta:
        abstract = True

The hard-coded model manager works very well:

class MixedModelManager(Manager):
    def get_by_natural_key(self, name, version):
        return self.get(name=name, version=version)