Implement plugins to detect declarative bases

[ilevkivskyi]

We currently can only detect declarative bases defined using @as_declarative, a plugin for detecting declarative_base() depends on python/mypy#5508

[ilevkivskyi]

A potential problem here is how to store the fact that given TypeInfo is "special". We can of course just store something in TypeInfo.metadata, but other plugin hooks will only see the full name of this class. So maybe we need to keep some state in a plugin with all special class names. The question is then however how to recreate the state in incremental mode (when classes are loaded from cache).

[mehdigmira]

Any news on this ?

Currently declarative_base() seems to be inferred as Any.

[mehdigmira]

This doesn't seem to be fixed by #49
I'm using mypy v0.660

from typing import Any

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


Base = declarative_base()
reveal_type(Base)  # revealed type is Any


class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)


class Address(Base):
    __tablename__ = 'addresses'
    id = Column(Integer, primary_key=True)
    name = Column(String)


def f() -> Address:
    user = User(name="xx")
    return user  # mypy should log an error here but doesn't

[ilevkivskyi]

It is. This is what I see

  main:8: error: Revealed type is 'def () -> main.Base'
  main:25: error: Incompatible return value type (got "User", expected "Address")

You need to enable the plugin in mypy config. Next time please make at least minimal effort before complaining.

[mehdigmira]

Ah sorry, I thought it would be enabled by installing sqlalchemy-stubs. My bad. I'm not complaining. I think you guys are doing great work, and i'm very grateful :) ! I just report bugs or issues when i think there are ones. I always do my best to reproduce a problem on a minimal case before reporting. Plugins are not smth that is well documented, so it's sometimes hard to understand for an outsider. Thanks for the answer anyway ! Le 17 janv. 2019 4:21 PM, "Ivan Levkivskyi" <notifications@github.com> a écrit :

…

It is. This is what I see main:8: error: Revealed type is 'def () -> main.Base' main:25: error: Incompatible return value type (got "User", expected "Address") You need to enable the plugin in mypy config. Next time please make at least minimal effort before complaining. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#6 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ANBd8MmXHh_W6FapNL1Ohr6R89S6jixAks5vEJTpgaJpZM4WN-5s> .

[JukkaL]

I wonder if the installation instructions in https://github.com/dropbox/sqlalchemy-stubs/blob/master/README.md are up-to-date with respect to the plugin?

[ilevkivskyi]

@mehdigmira OK, I am sorry for being harsh, it's great that we found understanding.

@JukkaL Yes, I will update this before making the release.