Advanced user inheritance with Django

models.py

from django.db import models
from django.utils import timezone
from django.contrib.auth.models import (AbstractBaseUser,
                                        BaseUserManager as DjBaseUserManager)

from model_utils.managers import InheritanceManager


class BaseUserManager(DjBaseUserManager, InheritanceManager):
    """
    Manager for all Users types
    create_user() and create_superuser() must be overriden as we do not use
    unique username but unique email.
    """

    def create_user(self, email=None, password=None, **extra_fields):
        now = timezone.now()
        email = BaseUserManager.normalize_email(email)
        u = GenericUser(email=email, is_superuser=False, last_login=now,
                        **extra_fields)
        u.set_password(password)
        u.save(using=self._db)
        return u

    def create_superuser(self, email, password, **extra_fields):
        u = self.create_user(email, password, **extra_fields)
        u.is_superuser = True
        u.save(using=self._db)
        return u


class CallableUser(AbstractBaseUser):
    """
    The CallableUser class allows to get any type of user by calling
    CallableUser.objects.get_subclass(email="my@email.dom") or
    CallableUser.objects.filter(email__endswith="@email.dom").select_subclasses()
    """
    objects = BaseUserManager()


class AbstractUser(CallableUser):
    """
    Here are the fields that are shared among specific User subtypes.
    Making it abstract makes 1 email possible in each User subtype.
    """
    email = models.EmailField(unique=True)
    is_superuser = False
    objects = BaseUserManager()

    def __unicode__(self):
        return self.email

    USERNAME_FIELD = 'email'
    REQUIRED_FIELD = USERNAME_FIELD

    class Meta:
        abstract = True


class GenericUser(AbstractUser):
    """
    A GenericUser is any type of system user (such as an admin).
    This is the one that should be referenced in settings.AUTH_USER_MODEL
    """
    is_superuser = models.BooleanField(default=False)


class Professional(AbstractUser):
    """
    User subtype with specific fields and properties
    """
    company = models.CharField(max_length=50)


class Individual(AbstractUser):
    """
    User subtype with specific fields and properties
    """
    name = models.CharField(max_length=50)

tests.py

from django.test import TestCase
from django.db import IntegrityError

from .models import Individual, Professional, GenericUser, CallableUser


class SimpleTest(TestCase):

    def test_user_has_email(self):
        user = Individual.objects.create(email="me@home.test")
        self.assertEquals(user.email, "me@home.test")

    def test_user_unique_for_type(self):
        Individual.objects.create(email="me@home.test")
        user2 = Individual(email="me@home.test")
        self.assertRaises(IntegrityError, user2.save)

    def test_user_multiple_for_types(self):
        Individual.objects.create(email="me@home.test")
        try:
            Professional.objects.create(email="me@home.test")
        except IntegrityError:
            self.fail("A user account could not be saved with this email")

    def test_create_user(self):
        GenericUser.objects.create_user(email="me@home.test",
                                        password="cantfindthis")
        user = GenericUser.objects.get(email="me@home.test")
        self.assertFalse(user.is_superuser)

    def test_create_superuser(self):
        GenericUser.objects.create_superuser(email="me@home.test",
                                             password="cantfindthis")
        user = GenericUser.objects.get(email="me@home.test")
        self.assertTrue(user.is_superuser)

    def test_specific_users_are_not_superusers(self):
        user = Individual.objects.create(email="me@home.test")
        self.assertFalse(user.is_superuser)
        user = Professional.objects.create(email="me@home.test")
        self.assertFalse(user.is_superuser)

    def test_retrieve_a_user_type(self):
        Individual.objects.create(email="me@home.test")
        user_pk = Individual.objects.get(email="me@home.test").pk
        self.assertIsInstance(CallableUser.objects.get_subclass(pk=user_pk),
                              Individual)