Type hints don't work on Motor?

Working with Data Drivers
1

The docs say that type hints are supported. So I tried that.

client: AsyncIOMotorClient = AsyncIOMotorClient()
collection: AsyncIOMotorCollection[Movie] = client.test.test

However, mypy gives me:

“AsyncIOMotorCollection” expects no type arguments, but 1 given

Pylance also gives a similar message. Did they remove it at some point? For some reason, I can’t find any mention of this on the internet. Apologies if this has been brought up before.

Here are my versions:
Python 3.9.21
pymongo 4.6.3
motor 3.4.0

2

What version of mypy are you using?

Here’s what I see locally with the latest mypy (1.10.1):

$ cat test/check_runtime_types.py 
from typing import Any, Dict

from motor.motor_asyncio import (
    AsyncIOMotorChangeStream,
    AsyncIOMotorClient,
    AsyncIOMotorClientEncryption,
    AsyncIOMotorCollection,
    AsyncIOMotorCursor,
    AsyncIOMotorDatabase,
)

client: AsyncIOMotorClient[Dict[str, Any]]
db: AsyncIOMotorDatabase[Dict[str, Any]]
cur: AsyncIOMotorCursor[Dict[str, Any]]
coll: AsyncIOMotorCollection[Dict[str, Any]]
cs: AsyncIOMotorChangeStream[Dict[str, Any]]
enc: AsyncIOMotorClientEncryption[Dict[str, Any]]
$ mypy --strict test/check_runtime_types.py
Success: no issues found in 1 source file
3

Running mypy 1.15.0. It’s actually running inside a python:3.9.21-slim-bookworm docker container if that’s any help. Here’s the output for that file.

test.py:12: error: “AsyncIOMotorClient” expects no type arguments, but 1 given [type-arg]
test.py:13: error: “AsyncIOMotorDatabase” expects no type arguments, but 1 given [type-arg]
test.py:14: error: “AsyncIOMotorCursor” expects no type arguments, but 1 given [type-arg]
test.py:15: error: “AsyncIOMotorCollection” expects no type arguments, but 1 given [type-arg]
test.py:16: error: “AsyncIOMotorChangeStream” expects no type arguments, but 1 given [type-arg]
test.py:17: error: “AsyncIOMotorClientEncryption” expects no type arguments, but 1 given [type-arg]
Found 6 errors in 1 file (checked 1 source file)

4

And what motor version are you using? Are you sure it’s 3.4?

5

Yes. Both pip list and poetry show motor tell me it’s 3.4.0. I’m not sure what’s gone wrong. Could it be the python version?

6

Oh now I just feel silly. Seems all I needed was to just update pymongo and motor to the latest versions. The dockerfile I used had something to do with it as well. I would install the dependencies inside a non-slim python image and then copy over the venv folder to the slim python image. For whatever reason, that breaks in the older versions. I should note that those older versions did work as long as I didn’t do the venv copying.

All good now. Thanks for your time.