Can not cognize type of model's real type in mypy

[barking-code]

Apache Airflow version

Other Airflow 2 version (please specify below)

If "Other Airflow 2 version" selected, which one?

2.9.0

What happened?

This code makes Incompatible types error after updating to Airflow 2.7.0 from 2.6.3.
I used sqlalchemy2-stubs==0.0.2a38 and mypy==1.5.0 in both versions. And I also use python3.10.14

from airflow.hooks.base import BaseHook

s: str = BaseHook.get_connection("conn_id").conn_id  # raise an Incompatible types error

What you think should happen instead?

No response

How to reproduce

1. install airflow

pip install apache-airflow==2.7.0 --constraint https://raw.githubusercontent.com/apache/airflow/constraints-2.7.0/constraints-3.10.txt

2. install mypy and sqlalchemy2-stubs

pip install mypy==1.5.0 sqlalchemy2-stubs==0.0.2a38

3. copy mypy.ini

[mypy]
plugins = sqlalchemy.ext.mypy.plugin

4. copy code

from airflow.hooks.base import BaseHook

s: str = BaseHook.get_connection("conn_id").conn_id  # raise an Incompatible types error

5. run mypy

mypy mypy --config-file={path of mypy.ini} {path of python file}

Operating System

macOS Ventura: 13.0.1 (22A400)

Versions of Apache Airflow Providers

No response

Deployment

Other

Deployment details

No response

Anything else?

No response

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[boring-cyborg[bot]]

Thanks for opening your first issue here! Be sure to follow the issue template! If you are willing to raise PR to address this issue please do so, no need to wait for approval.

[potiuk]

I think it's a very good issue - but you should likely open it in sqlalchemy repo.

[barking-code]

Hi, @potiuk. First of all, thank you for your comment :)
I think it's an Airflow problem because I used the same versions of SQLAlchemy, and sqlalchemy2-stubs.
The only major change is the Airflow Version(2.6.2 -> 2.9.0)

I also tested further and found that the error was raised when the Airflow version changed from 2.6.3 to 2.7.0.
In this case, SQLAlchemy and sqlalchemy2-stubs versions were not changed.

SQLAlchemy: 1.4.49
sqlalchemy2-stubs: 0.0.2a38

I apologize for not being well-versed in SQLAlchemy, and I would appreciate it if you could share your opinion.

[potiuk]

Well. The community explicitly specified in our documentation that Airflow DB models ARE NOT a part of public interface of Airflow - https://airflow.apache.org/docs/apache-airflow/stable/public-airflow-interface.html#what-is-not-part-of-the-public-interface-of-apache-airflow so if you decide to use them directly, you are pretty much on your own to solve your problems. Our CI verify with mypy all the usages of sqlalchemy for Airflow, so this is fine. But if you decided to do somethin with SQLAlchemy models on your own - against the advices we gave at the "Public interface" then if something does not work for you, you won't get much help from Airflow maintainers (we specifically mentioned that so that we do not have to loose our time on solving similar issues). My recommendation is to stop modifying Airflow models (becasue they are internal detail of Airflow) and find other ways to achieve whatever you want to achieve - Airflow 3 will likely have HUGE changes to the database, including likely rewriting some of the base models, so you should not rely on thos models to continue working as they are.

If you chose to work with SQL Alchemy models directly, you need to become expert in that - this is noit something you will get a lot of help here, this is why I suggested asking this question in SQLAlachemy forums.

[barking-code]

@potiuk
Thank you for your kind explanation.
I think I caused a misunderstanding. I am not modifying Airflow DB model. The code I shared is test code for raising the same error I encountered. I am just using it this way.
(e.g id: str = BaseHook.get_connection().conn_id)
So, I expected a bit of help from the community. You mentioned that all the usages of SQLAlchemy for Airflow were verified with mypy, so I think something is wrong with my local setup.
Thank you for your opinion and for the notice about the changes in Airflow 3.

[potiuk]

So maybe better to explain the exact error you have and intentions you have, rather than coming up with generic SQL-alchemy-looking-like piece of code? I am sure that if you explain exactly what you try to do (from these explanations you gave I am still not sure what kind of error you have - because the original example and what you shared in your comment are pretty different).

So you might get help, but make sure you specify the problem you have in the way that will allow others to help you,

[barking-code]

@potiuk
I updated the issue to make it simpler. I found the code causing the problem, so I will open a PR and fix it.
I appreciate your interest. :)