Accessing attributes in modules imported by import_module

[pawelswiecki]

Are you reporting a bug, or opening a feature request?
I believe I found a bug in mypy (as far as I understand what's going on, this is not a typeshed issue).

The code

# my_file.py
from importlib import import_module
import os

settings_module_path = os.getenv('PRODUCTION_SETTINGS_MODULE')
settings = import_module(settings_module_path)

if settings and hasattr(settings, 'LOGGING'):
    log_config = settings.LOGGING

Behaviour

$ mypy 
my_file.py:8: error: Module has no attribute "LOGGING"

Expected behavior
No mypy error. Especially, when the attribute is explicitly asserted to be there (analogically as with narrowing types using isinstance()).

Versions
Python 3.6.5
mypy==0.600

[emmatyping]

This is a duplicate of #1424, we don't currently support hasattr checks.

[pawelswiecki]

Thank you for the reply.

This issue is not about hasattr checks, though. (It was just a suggestion how it could be dealt with.) It's about modules imported using import_module. Shouldn't mypy approach differently to them? Adding # type: ignore seems the only option I have, which I'd love to avoid.

[emmatyping]

Importing something based on an environment variable is too dynamic, mypy cannot statically know what module you are reffering to.

importlib.import_module returns type types.ModuleType. We don't know anything else about the attributes of that module, beyond the attributes of that type. Therefore, the error message boils down to #1424.

Perhaps we should warn when someone calls __import__, importlib.import_module or the like, because it almost always requires a type ignore.

[pawelswiecki]

Right, I get it, thanks for the explanation. Sometimes it's unavoidable to use import_module (as in my example), warning won't help in my opinion, since the user is probably aware of the situation. I will wait for resolving #1424. Thanks again.

[JukkaL]

I think that the return type of importlib.import_module should be Any, similar to how the type of getattr is Any.

[JelleZijlstra]

Or perhaps types.ModuleType should grow a def __getattr__(self, attr) -> Any, because modules can have arbitrary attributes.

[patrick91]

I'm having problem with this too:

@strawberry.type
class TypeB:
    @strawberry.field(
        type=lambda: importlib.import_module(".type_a", __package__).TypeA
    )
    def type_a(self, info) -> "TypeA":
        from .type_a import TypeA

        return TypeA()

I get this error:

Module has no attribute "TypeA"mypy(error)

Which can only be fixed by using # type: ignore