psycopg2-stubs shadow typeshed stubs

[ewjoachim]

It took me a while to find that it was this package that caused my issue.

There are more complete stubs of psycopg2 in typeshed: https://github.com/python/typeshed/tree/master/stubs/psycopg2 which are automatically released as a PEP 561 package at https://pypi.org/project/types-psycopg2/

Installing both types-psycopg2 and django-types results in one unpredictibly shadowing the other, so mypy sometimes works and sometimes doesn't. Would you accept a PR that would remove psycopg2 types defined here and rely on the typeshed ones instead ?

[sbdchd]

Yeah that works for me, the only downside I see is the types in the type shed aren't as fleshed out

[ewjoachim]

I don't know if the stubs in typeshed are less complete.
What I can say is that psycopg2.extra.Json exists in typeshed and in psycopg2 but not in here. So does psycopg2.pool.

The people over at typeshed are quick to merge PRs, so it shouldn't be too hard to add missing stuff there.

[sbdchd]

Yeah I think the type shed will have more stubs since it was created using stub gen, but right now they're a little thin on the type annotations

for instance parse_dsn is typed as Any -> Any and the connection cursor has an __enter__ return type of Any which means if we use the cursor like:

with connection.cursor() as conn:
    conn # this will be Any

[ewjoachim]

Looking at the stubs here, I'm seeing that connection.cursor would return a cursor instance whose fetchone type is a Tuple. But if you configured your connection's cursor_factory to use a DictCursor, then fetchone will return a Dict. I know that it might not make a lot of sense in the context of Django, but this means we can have a lot of problems if the project uses psycopg2 directly alongside with Django.
Also... How do we know it's psycopg2 and not, say, MariaDB or sqlite ?

[sbdchd]

Revisiting this, I think removing the psycopg2 types from this package and using the type shed ones is the way forward

[ewjoachim]

(had completely forgotten about this issue. Not sure I have a lot of time to make a PR)