Type is not callable error using SQLAlchemy's declarative_base

[nirn]

Environment data

• Language Server version: 2020.10.1
• OS and version: Windows 10, 2004
• Python version (& distribution if applicable, e.g. Anaconda): 3.8.3

Expected behaviour

No errors.

Actual behaviour

Two errors appear:

"User" has type "Type[User]" and is not callable
  Type "Type[User]" is not callable Pylance (reportGeneralTypeIssues)
Expected no arguments to "User" constructor Pylance (reportGeneralTypeIssues)

Code Snippet / Additional information

from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()


class User(Base):
    id = Column(Integer, primary_key=True, index=True)
    username = Column(String(255), unique=True, index=True)


user = User(id=1, username='test')

SQLAlchemy's declarative_base should use this _declarative_constructor by default, which allows initialization from kwargs.
There are no errors for the same snippet using standalone Pyright (1.1.80) without Pylance.

[erictraut]

Thanks for the bug report. SqlAlchemy is using a custom metaclass that provides non-standard behaviors for a constructor. I've changed the logic in pylance to avoid emitting this particular error when a class is instantiated from a custom metaclass, so you won't see this false positive in the future.

This fix will be in the next release of pylance.

[jakebailey]

This issue has been fixed in version 2020.10.2, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/master/CHANGELOG.md#2020102-21-october-2020

[jakebailey]

This issue has been fixed in version 2020.10.3, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/master/CHANGELOG.md#2020103-28-october-2020

[aaronkavlie-wf]

I still get the "Expected no arguments" bug on SQLAlchemy model class initialization.

(running Pylance 2020.11.1)

[erictraut]

I just re-verified that the code sample above does not result in any errors. If your code differs from the above, please post a simple example that exhibits the problem.

[aaronkavlie-wf]

I just re-verified that the code sample above does not result in any errors. If your code differs from the above, please post a simple example that exhibits the problem.

Sorry about the trouble Eric, the errors are gone now. I think my workspace just wasn't pointed at my virtualenv's Python interpreter.