Pydantic Factories and Models That Require "init"

[rgajason]

Updated: Original question missed the Beanie extension in pydantic_factories. See comments in accepted answer.

I'd like to use Pydantic Factories on Beanie models. These models are an extension of pydantic.BaseModel. An init_beanie() function needs to be ran prior to using the classes. In Starlite, this is done using on_startup:

from beanie import Document, init_beanie
from motor.motor_asyncio import AsyncIOMotorClient
from starlite import Starlite, State

import myapp.dependencies.get_settings

class Widget(Document):
    name: str

async def initialize_beanie(state: State) -> None:
    settings = get_settings()
    cx = AsyncIOMotorClient(settings.mongodb_url, uuidRepresentation="standard")
    db = getattr(cx, settings.mongodb_db)
    await init_beanie(
        database=db,
        document_models=[Widget],
        allow_index_dropping=True,
    )

app = Starlite(
    route_handlers=[SandboxController],
    on_startup=[initialize_beanie],
    dependencies={"settings": Provide(get_settings, use_cache=True)},
)

I'm trying to figure out where would be best to do something similar when using ModelFactory:

import pytest

from pydantic_factories import ModelFactory

from myapp.models import Widget


class WidgetFactory(ModelFactory[Widget]):
    __model__ = Widget


@pytest.fixture()
def widget():
    return WidgetFactory.build()

def test_widget(widget: Widget):
    assert isinstance(widget.name, str)

The above code will raise CollectionWasNotInitialized.

Would it make sense to extend __init__ and maybe have it call Beanie's init?

[rgajason]

async vs sync further complicates this... I tried being tricky with Faker in my conftest.py:

import asyncio
from random import random

import pytest
from beanie import init_beanie
from mongomock_motor import AsyncMongoMockClient

from myapp.models import Widget


@pytest.fixture(scope="session", autouse=True)
def faker_seed():
    client = AsyncMongoMockClient()
    asyncio.run(init_beanie(database=client.beanie_test, document_models=[Widget]))
    return random()

That gets me passed CollectionWasNotInitialized.

In reality, though, my data has references / links and the moment I try and add a model that has a link things blow up (RecursionError).

Example that demonstrates recursion error:

models.py

from beanie import Document, Indexed, Link


class Parent(Document):
    name: Indexed(str, unique=True)

    class Settings:  # Beanie configuration
        name = "sandbox-parents"

    class Config:  # Pydantic configuration
        schema_extra = {
            "example": {
                "name": "Parent Name Goes Here",
            },
        }


class Child(Document):
    parent: Link[Parent]
    name: Indexed(str, unique=True)

    class Settings:  # Beanie configuration
        name = "sandbox-children"

    class Config:  # Pydantic configuration
        schema_extra = {
            "example": {
                "parent": "document ID of parent goes here",
                "name": "Child Name Goes Here",
            },
        }

conftest.py

import asyncio
from random import random

import pytest
from beanie import init_beanie
from mongomock_motor import AsyncMongoMockClient

from myapp.models import Child, Parent


@pytest.fixture(scope="session", autouse=True)
def faker_seed():
    client = AsyncMongoMockClient()
    asyncio.run(
        init_beanie(database=client.beanie_test, document_models=[Parent, Child])
    )
    return random()

test_mystuff.py

import pytest
from pydantic_factories import ModelFactory

from myapp.models import Child, Parent


class ParentFactory(ModelFactory[Parent]):
    __model__ = Parent


@pytest.fixture()
def parent():
    return ParentFactory.build()


class ChildFactory(ModelFactory[Child]):
    __model__ = Child


@pytest.fixture()
def child():
    return ChildFactory.build()


@pytest.mark.asyncio()
async def test_parent(parent: Parent):
    assert isinstance(parent.name, str)


@pytest.mark.asyncio()
async def test_child(child: Child):
    assert isinstance(child.name, str)

Results in:

ERROR tests/test_sandbox.py::test_child - RecursionError: maximum recursion depth exceeded while calling a Python object

...on the return ChildFactory.build() line.

[Goldziher]

I enabled discussions in the pydantic-factories repo, please move there and delete this discussion

[rgajason]

Oh wow, after all that I completely missed that there is a BeanieDocumentFactory... Well I feel dumb...

[Goldziher]

well, at least you are thorough 😉

[rgajason]

For others who may stumble upon this, the init_beanie() hack is still required even when using the BeanieDocumentFactory:

models.py

from beanie import Document, Indexed, Link

class Bar(Document):
    name: str = "bar"

class Foo(Document):
    some_string: Indexed(str, unique=True)
    bar: Link[Bar]

conftest.py

import asyncio
from random import random

import pytest
from beanie import init_beanie
from mongomock_motor import AsyncMongoMockClient

from .models import Foo, Bar

@pytest.fixture(scope="session", autouse=True)
def faker_seed():
    client = AsyncMongoMockClient()
    asyncio.run(
        init_beanie(database=client.beanie_test, document_models=[Foo, Bar])
    )
    return random()

test_sandbox.py

import pytest
from pydantic_factories import BeanieDocumentFactory

from .models import Foo, Bar

class FooFactory(BeanieDocumentFactory):
    __model__ = Foo

# This would result in a Beanie "CollectionWasNotInitialized" error
# (doesn't use "faker_seed()" from "conftest.py")
# result = FooFactory.build()

# But this works
@pytest.fixture()
def foo():
    return FooFactory.build()

def test_foo(foo: Foo):
    assert isinstance(foo.some_string, str)