Factory Boy aim is to replace static and hard to maintain complex object fixtures (test data).

This is test data created with factory boy (We need a 200€, paid order, shipping to australia, for a VIP customer):

def test_with_factory_boy(self):
	order = OrderFactory(
		amount=200,
		status='PAID',
		customer__is_vip=True,
		address__country='AU',
	)

This is data created without factory boy:

def test_without_factory_boy(self):
	address = Address(
		street="42 fubar street",
		zipcode="42Z42",
		city="Sydney",
		country="AU",
	)
	customer = Customer(
		first_name="John",
		last_name="Doe",
		phone="+1234",
		email="john.doe@example.org",
		active=True,
		is_vip=True,
		address=address,
	)

$ pip install factory_boy

from factory.mongoengine import MongoEngineFactory
# ...
class User(Document):
# ...
class UserFactory(MongoEngineFactory):

Factories declare a set of attributes for an object. The class of this object must be defined in the model attribute of a subclass Meta ( In previous versions the class Meta with its attribute model it is substituted by FACTORY_FOR attribute):

import factory
import models
 
class UserFactory(factory.Factory):
    class Meta:
        model = models.User
 
    first_name = 'John'
    last_name = 'Doe'
    admin = False

From here we can:

# Build a not saved user
user = UserFactory.build()
# Build a saved user
user = UserFactory.create()
# Build a saved user
user = UserFactory()
# Returns a dict of attributes that can be used to build a user
attributes = UserFactory.attributes()
# Build a not saved user overriding its first_name
user = UserFactory.build(first_name='Joe')
# Build ten not saved users named Joe
users = USerFactory.build(10, first_name="Joe")

We can create a field which is derived from others (this example will put joe.blow@example.com in email field):

class UserFactory(factory.Factory):
    FACTORY_FOR = models.User
    first_name = 'Joe'
    last_name = 'Blow'
    email = factory.LazyAttribute(lambda a: '{0}.{1}@example.com'.format(a.first_name, a.last_name).lower())

We can create a field which is auto-incremented as:

class UserFactory(factory.Factory):
    FACTORY_FOR = models.User
    email = factory.Sequence(lambda n: 'person{0}@example.com'.format(n))

We can associate a field with other factory to create other sub instance:

class PostFactory(factory.Factory):
    FACTORY_FOR = models.Post
    author = factory.SubFactory(UserFactory)