Unexpected behavior when providing foreign key id instead of relationship when dealing with ORM factory

[paulshih85]

Description

I've created an ORM factory that generates a must-have relationship using SubFactory by default.
I expected it'll be replaced if I provide either the foreign key ID or the related object, but it didn't.

To Reproduce

There's a working example below.

Model / Factory code

# Model
class User(Base):
    __tablename__ = 'user'

    address_id = Column('address_id', Integer, ForeignKey('address.id', ondelete='CASCADE'), index=True, nullable=False)
    address = relationship('Address', cascade='all, delete')

# Factory
class AddressFactory(factory.Factory):

    class Meta:
        model = Address


class UserFactory(factory.Factory):

    class Meta:
        model = User

    address = factory.SubFactory(AddressFactory)

The issue

address = AddressFactory.build()
session.add(address)
session.commit()

user = UserFactory.build(address_id=address_id)

I expected that the created user's address would be the address I provided, but it seems that it is covered by the address created by the subfactory.

[rbarrois]

Indeed, factory_boy does not inspect your model structure; nor is it aware of the magic performed by the ORM library.

In its view, the address and address_id fields are unrelated, and live separate lives.

If you pass in (address_id=address_id, address=None), the second part will prevent the subfactory to be built.
You'll have to check whether your ORM behaves as you'd expect when calling User(address=None, address_id=42)

If that works, I'll be glad to add that suggestion to the documentation's common recipes section!