Using sqlmodel with pytest and factory boy

[farridav]

First Check

• I added a very descriptive title here.
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• I already checked if it is not related to SQLModel but to SQLAlchemy.

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Example Code

# example.py

from typing import Optional

from factory.alchemy import SQLAlchemyModelFactory
from sqlmodel import Field, Session, SQLModel, create_engine, select

sqlite_url = "sqlite://"
engine = create_engine(sqlite_url)
session = Session(engine)


class Hero(SQLModel, table=True):
    id: Optional[int] = Field(default=None, primary_key=True)
    name: str = Field(index=True)
    secret_name: str
    age: Optional[int] = Field(default=None, index=True)


class HeroFactory(SQLAlchemyModelFactory):
    class Meta:
        model = Hero
        sqlalchemy_session = session

    name = "Superman"
    secret_name = "Clark Kent"
    age = 1000


def create_db_and_tables():
    SQLModel.metadata.create_all(engine)


def list_heroes():
    with Session(engine) as session:
        statement = select(Hero)
        heroes = session.exec(statement).all()

    return heroes


def test_list_heroes():
    create_db_and_tables()

    HeroFactory(name="Batman", secret_name="Bruce Wayne", age=50)
    heroes = list_heroes()

    assert len(heroes) == 1

Description

• Install deps pip install factory-boy pytest sqlmodel
• Setup model, engine and connection
• Make factory
• Make function that returns all models
• Test instance is created
• Call function that returns model instances
• Run test with pytest example.py

This doesn't appear to work for me, and i may have misunderstood something in the way things are setup with session management (im more familiar with django, that abstracts session management away)

I'm happy to move to a different library if factory boy is not well suited to this, e.g https://github.com/litestar-org/polyfactory
i just need something that i can easily generate dynamic fixtures with.

Ive also tried various pytest fixtures e.g:

@pytest.fixture(scope="module", autouse=True)
def db_session() -> Generator[Session, Any, None]:
    SQLModel.metadata.create_all(engine)

    yield session

    session.rollback()
    session.close()

but I'm unsure on how best to set this up, any advice is appreciated

Operating System

Linux

Operating System Details

No response

SQLModel Version

0.0.8

Python Version

Python 3.10.11

Additional Context

No response

[farridav]

I have managed to resolve this using the following structure:

conftest.py

import os
from typing import Any, Generator

import pytest
from factory.alchemy import SQLAlchemyModelFactory
from sqlmodel import Session, SQLModel

# Ensure our engine is shared
from my_app.database import engine


@pytest.fixture(scope="module")
def db_session() -> Generator[Session, Any, None]:
    from . import factories  # NOQA

    SQLModel.metadata.create_all(engine)
    session = Session(engine)

    # Ensure that all factories use the same session
    for factory in SQLAlchemyModelFactory.__subclasses__():
        factory._meta.sqlalchemy_session = session

    yield session

    session.rollback()
    session.close()

factories.py

from factory.alchemy import SQLAlchemyModelFactory


class UserFactory(SQLAlchemyModelFactory):
    class Meta:
        model = User
        sqlalchemy_session_persistence = "commit"

    ...

test.py

def test_get_valid_users(db_session: Session) -> None:
    user = UserFactory()
    users = get_users()

    assert len(users) == 1

Basically i was getting tripped up by a few things

• The fact that factory boy wanted a shared session object (or a scoped session), and this wasn't available to me using sqlmodel
• I was missing an important sqlalchemy_session_persistence = "commit" within my factory
• That and I'm still learning the basics of session management in sqlalchemy.

Being able to patch the factories session in from within my pytest fixture, gives me the convenience of all data being available in the session within my pytest scope, but given that each time i interact with the db, i create a new session, i needed to commit previous changes, which factory boy was not doing by default because of sqlalchemy_session_persistence defaulting to None

Ill be leaving this discussion open for a few more days in case anyone sees it and has a cleaner pattern to follow, or spots anything fundamentally wrong with my approach.