Mocking Django AUTH_PROFILE_MODULE without a Database

Difio is a Django based service which uses a profile model to provide site-specific, per-user information. In the process of open sourcing Difio its core functionality becomes available as a Django app. The trouble is that the UserProfile model contains site-specific and proprietary data which doesn't make sense to the public nor I want to release it.

The solution is to have a MockProfile model and work with that by default while www.dif.io and other implementations override it as needed. How do you do that without creating useless table and records in the database but still have the profiles created automatically for every user?

It turns out the solution is quite simple. See my comments inside the code below.

class AbstractMockProfile(models.Model):
    """
        Any AUTH_PROFILE_MODULE model should inherit this
        and override the default methods.

        This model provides the FK to User!
    """
    user = models.ForeignKey(User, unique=True)

    def is_subscribed(self):
        """ Is this user subscribed for our newsletter? """
        return True

    class Meta:
        # no DB table created b/c model is abstract
        abstract = True

class MockProfileManager(models.Manager):
    """
        This manager creates MockProfile's on the fly without
        touching the database. It is needed by User.get_profile()
        b/c we can't have an abstract base class as AUTH_PROFILE_MODULE.
    """
    def using(self, *args, **kwargs):
        """ It doesn't matter which database we use! """
        return self

    def get(self, *args, **kwargs):
        """
            User.get_profile() calls .using(...).get(user_id__exact=X)
            so we instrument it here to return a MockProfile() with
            user_id=X parameter. Anything else may break!!!
        """
        params = {}
        for p in kwargs.keys():
            params[p.split("__")[0]] = kwargs[p]

        # this creates an object in memory. To save it to DB
        # call obj.save() which we DON'T do anyway!
        return MockProfile(params)


class MockProfile(AbstractMockProfile):
    """
        In-memory (fake) profile class used by default for
        the AUTH_PROFILE_MODULE setting.
    """
    objects = MockProfileManager()

    class Meta:
        # DB table is NOT created automatically
        # when managed = False
        managed = False

In Difio core the user profile is always used like this

profile = request.user.get_profile()
if profile.is_subscribed():
    pass

and by default

AUTH_PROFILE_MODULE = "difio.MockProfile"

Voila!

Comments !