DjangoModelFactory with mixins

Hi guys, I was wondering how to write factories that shares the same attributes, such as created_by and modified_by. Suppose I have 2 models: Car and Manufacturer which has these 2 attributes, and in the Factory classes I wrote something like these:

class Car(models.Model):
    title = models.CharField()
    created_by = models.ForeignKey(User)
    modified_by = models.ForeignKey(User)

class Manufacturer(models.Model):
    title = models.CharField()
    created_by = models.ForeignKey(User)
    modified_by = models.ForeignKey(User)

class UserFactory(DjangoModelFactory)
    FACTORY_FOR = User

class UserStampMixin(object):
    @lazy_attribute
    def created_by(self): return UserFactory()

    @lazy_attribute
    def modified_by(self): return UserFactory()

class CarFactory(UserStampMixin, DjangoModelFactory)
    FACTORY_FOR = Car
    title = Sequence(lambda n: "Car %03d" % n)

class ManufacturerFactory(UserStampMixin, DjangoModelFactory)
    FACTORY_FOR = Manufacturer
    title = Sequence(lambda n: "Manufacturer %03d" % n) 

When accessing CarFactory.attributes() and ManufacturerFactory.attributes(), I get only {'title': '<sequence>'}, so all my factory classes are throwing error because user stamp can’t be null. Tried with several different ways but the results are just the same. Does Factory Boy support mixins?

[rbarrois]

@danihodovic the solution should be using simple inheritance with a class Meta: abstract = True in factories. An example follows:

import collections
import factory
import factory.fuzzy


Car = collections.namedtuple('Car', ['brand', 'plate', 'mileage'])
Bus = collections.namedtuple('Bus', ['brand', 'plate', 'capacity'])


class VehicleFactory(factory.Factory):
    class Meta:
        abstract = True

    brand = factory.Iterator(['peugeot', 'renault', 'delorean'])
    plate = factory.fuzzy.FuzzyText(length=7)


class CarFactory(VehicleFactory):
    class Meta:
        model = Car
    mileage = factory.fuzzy.FuzzyInteger(0, 10000)


class BusFactory(VehicleFactory):
    class Meta:
        model = Bus
    capacity = factory.fuzzy.FuzzyInteger(20, 50)


print(BusFactory())
print(CarFactory())

[aalvrz]

Was there any consensus on what is the best way to implement this?