Pyright in "strict" mode complains about "begin_transaction"

[AlexanderPodorov]

When env.py is generated, this line is usually added:

from alembic.context import begin_transaction

VSCode (pylance/pyright) compains about it saying:
Type of "begin_transaction" is partially unknown
Most likely because of:

def begin_transaction() -> Union[_ProxyTransaction, ContextManager]:

where the type of ContextManager generic is not specified

Expected behavior
No warnings

Versions.

• OS: MacOS
• Python: 3.11.2
• Alembic: 1.10.1
• SQLAlchemy: 2.0.5.post1
• Database: Postgres 15
• DBAPI: asyncpg

Have a nice day!

[zzzeek]

thanks for reporting

cc @CaselIT

[CaselIT]

Thanks for reporting.

[CaselIT]

Please note that both alembic and sqlalchemy are currently "best effort" type checking with pyright/pylance. A lot of similar issues will came up running them, especially in strict mode

[sqla-tester]

CaselIT has proposed a fix for this issue in the main branch:

Correctly account for generic in Function https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/4492

[AlexanderPodorov]

Thanks for the note, that's fine. sqlalchemy and alembic are doing the great job of implementing proper type hinting!
I personally have not seen a lot of typing issues yet. Refining existing type hints is also great.
I would mention this particular issue is not related to pyright/pylance, mypy in strict mode will likely show a warning either (however I did not test that). I believe the respective setting for that is --disallow-any-generics. Thanks!

[CaselIT]

BTW I did not want to discourage future issues on this, just stating the current status of alembic and sqlalchemy