Incompatible with flask-sqlalchemy-3.0

[stabacco]

Looks like there has been a new major release for flask-sqlalchemy https://flask-sqlalchemy.palletsprojects.com/en/3.0.x/changes/#version-3-0-0 and they have broken backwards compatibility in a few places.

For example :

    @pytest.fixture(scope='function')
    def _transaction(request, _db, mocker):
        '''
        Create a transactional context for tests to run in.
        '''
        # Start a transaction
>       connection = _db.engine.connect()

../../../.cache/pypoetry/virtualenvs/api-S2mtXI53-py3.8/lib/python3.8/site-packages/pytest_flask_sqlalchemy/fixtures.py:31: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
../../../.cache/pypoetry/virtualenvs/api-S2mtXI53-py3.8/lib/python3.8/site-packages/flask_sqlalchemy/extension.py:642: in engine
    return self.engines[None]
../../../.cache/pypoetry/virtualenvs/api-S2mtXI53-py3.8/lib/python3.8/site-packages/flask_sqlalchemy/extension.py:628: in engines
    app = current_app._get_current_object()  # type: ignore[attr-defined]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

    def _get_current_object() -> T:
        try:
            obj = local.get()  # type: ignore[union-attr]
        except LookupError:
>           raise RuntimeError(unbound_message) from None
E           RuntimeError: Working outside of application context.
E           

Also the create_scoped_session method seems to have gone.

[zoltan-fedor]

Yeap, create_scoped_session method has been replaced by _make_scoped_session, see https://github.com/pallets-eco/flask-sqlalchemy/blob/2908083d0d0c918e1adce396d351da6fa3112692/src/flask_sqlalchemy/extension.py#L336, so that would need to be updated to that.

[Midnighter]

I believe a solution is to use SQLAlchemy directly:

from sqlalchemy.orm import sessionmaker, scoped_session

db.session = scoped_session(session_factory=sessionmaker(bind=db_connection))

[pamelafox]

Thanks @Midnighter ! If folks are looking for a workaround for now, this is the conftest.py I'm using with latest flask-sqlalchemy for similar purposes - not as comprehensive as this package, but works for a fake session:

https://github.com/pamelafox/flask-surveys-container-app/blob/main/backend/tests/conftest.py

[davidism]

I'm not sure exactly how this library works, but the way config, engines, and the session are managed did change significantly in Flask-SQLAlchemy 3.0. Just monkeypatching db.session as suggested above might work for simple cases, but I have a feeling it will fail in weird ways.

The following code sets up transactions for each bind, then rolls them back after each test. This supports multiple binds, in case one request queries multiple databases.

@pytest.fixture
def db(app):
    with app.app_context():
        engines = db.engines

    cleanup = []

    for key, engine in engines.items():
        c = engine.connect()
        t = c.begin()
        engines[key] = c
        cleanup.append((key, engine, c, t))

    yield db

    for key, engine, c, t in cleanup:
        t.rollback()
        c.close()
        engines[key] = engine

[jasondoong]

I'm not sure if this works in more complex situations, but it works in my project. https://github.com/Teachesworkspace/pytest-flask-sqlalchemy/commit/d6ae3d9e9292f2a61a3aa5bc988114a6ce36bf56

[gmassman]

If anyone was like me and had problems migrating pytest from SQLAlchemy <= 1.4 to SQLAlchemy 2.0, I created a minimum working example and was able to backtrack through my own test suite to find out why transactional tests weren't working.

https://github.com/gmassman/fsa-rollback-per-test-example