Use of __use_defaults

[impaktor]

Just writing, perhaps as a note to future self, that __use_defaults__ did not quite work as my intuition expected it to.

Mainly: it must be used on the outermost factory, i.e. to make Dog memeber varialbe barks = "Woof", __use_defaults__ must be declared in PetsFactory, not DogFactory, as I initially assumed.

code example

(Simplified toy example of equivalent problem)

from polyfactory.factories.pydantic_factory import ModelFactory
from pydantic import BaseModel, Field


class Dog(BaseModel):
    name: str
    barks: str = Field("Woof")


# class DogFactory(ModelFactory[Dog]):
#     __use_defaults__ = True


class Pets(BaseModel):
    dog: Dog


class PetsFactory(ModelFactory[Pets]):
    __use_defaults__ = True


d = PetsFactory.build().dict()
print(d)

For future self: I also had a bug where it still wouldn't "bark", and instead generate random string, as I'm also forced to use __set_as_default_factory_for_type__ for other classmethods. I relaize now that then it must also be combined with __use_defaults__:

class DogFactory(ModelFactory[Dog]):
    __set_as_default_factory_for_type__ = True
    __use_defaults__ = True

    @classmethod
    def name(cls):
        return "Pluto"

Hmm, interesting, in above code, I don't need __use_defaults__ on PetsFactory

Perhaps this is to help to some future person.

[adhtruong]

I think this is expected behaviour. If want to use a default on subfactory without setting __set_as_default_factory_for_type__, then you can use a factory as field. E.g.

from polyfactory.factories.pydantic_factory import ModelFactory
from pydantic import BaseModel, Field


class Dog(BaseModel):
    name: str
    barks: str = Field("Woof")


class DogFactory(ModelFactory[Dog]):
     __use_defaults__ = True


class Pets(BaseModel):
    dog: Dog


class PetsFactory(ModelFactory[Pets]):
    dog = DogFactory


d = PetsFactory.build().dict()
print(d)