Why do we need import TYPE_CHECKING in models?

[BEEugene]

Hi!

This is a great template project.
Why should we import type_checking in models?
from typing import TYPE_CHECKING
https://github.com/tiangolo/full-stack-fastapi-postgresql/blob/490c554e23343eec0736b06e59b2108fdd057fdc/%7B%7Bcookiecutter.project_slug%7D%7D/backend/app/app/models/item.py

As far as I understood this import is needed for linter, but how it works?
Does it somehow check database consistency?

[haviduck]

its for mypy, my guess is to lint relations while blocking with noqa

[raphant]

I think it's primarily for auto-completion while avoiding circular imports. In the link you provided, from .user import User # noqa: F401 will only import User for the sake of type checking. It will not execute any code from the .user module.