Some objects may use other complex objects as parameters; in order to simplify this setup, factory_boy provides the factory.SubFactory class.
This should be used when defining a Factory attribute that will hold the other complex object:
import factory
# A standard factory
class UserFactory(factory.Factory):
FACTORY_FOR = User
# Various fields
first_name = 'John'
last_name = factory.Sequence(lambda n: 'D%se' % ('o' * n)) # De, Doe, Dooe, Doooe, ...
email = factory.LazyAttribute(lambda o: '%s.%s@example.org' % (o.first_name.lower(), o.last_name.lower()))
# A factory for an object with a 'User' field
class CompanyFactory(factory.Factory):
FACTORY_FOR = Company
name = factory.Sequence(lambda n: 'FactoryBoyz' + z * n)
# Let's use our UserFactory to create that user, and override its first name.
owner = factory.SubFactory(UserFactory, first_name='Jack')
Instantiating the external factory will in turn instantiate an object of the internal factory:
>>> c = CompanyFactory()
>>> c
<Company: FactoryBoyz>
# Notice that the first_name was overridden
>>> c.owner
<User: Jack De>
>>> c.owner.email
jack.de@example.org
Fields of the SubFactory can also be overridden when instantiating the external factory:
>>> c = CompanyFactory(owner__first_name='Henry')
>>> c.owner
<User: Henry Doe>
# Notice that the updated first_name was propagated to the email LazyAttribute.
>>> c.owner.email
henry.doe@example.org
# It is also possible to override other fields of the SubFactory
>>> c = CompanyFactory(owner__last_name='Jones')
>>> c.owner
<User: Henry Jones>
>>> c.owner.email
henry.jones@example.org
In order to solve circular dependency issues, Factory Boy provides the CircularSubFactory class.
This class expects a module name and a factory name to import from that module; the given module will be imported (as an absolute import) when the factory is first accessed:
# foo/factories.py
import factory
from bar import factories
class FooFactory(factory.Factory):
bar = factory.SubFactory(factories.BarFactory)
# bar/factories.py
import factory
class BarFactory(factory.Factory):
# Avoid circular import
foo = factory.CircularSubFactory('foo.factories', 'FooFactory', bar=None)