microsoft
Wrong "Expected no arguments to <Flask SQL Alchemy> constructor"
Environment data
- Pylance version: v2024.7.1
- OS and version: Ubuntu 22.04.1 LTS running on WSL2
- Python version: 3.12.3 build from source
Code Snippet
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
class Base(DeclarativeBase):
pass
db = SQLAlchemy(model_class=Base)
class User(db.Model):
id: Mapped[int] = mapped_column(primary_key=True)
username: Mapped[str] = mapped_column(unique=True)
email: Mapped[str]
user = User(id=1, username='test')
print(user)
Output:
<User (transient 139732127139744)>
Expected behavior
No red squiggly lines around User to warn about error "Expected no arguments to "User" constructor". I've seen #507 and for SQL Alchemy models there's no squiggly lines but this isn't true for Flask-SQLAlchemy models, even if following Flask documentation.
Actual behavior
Can reproduce, with base SQLAlchemy.
from sqlalchemy.orm import Session
from sqlalchemy.ext.declarative import DeclarativeMeta, declarative_base
from sqlalchemy import Column, String
Base: DeclarativeMeta = declarative_base()
class Data(Base):
__tablename__ = "data"
id = Column(String(30), primary_key=True, index=True)
def test_func(db: Session):
db.add(Data(id="testid"))
I also want to point it out that when using unpacking syntax it doesn't raise any warnings or errors:
@senese, for Pylance to believe that that User has a generated __init__ method with id, username, and email parameters, User or one of its base classes would need to be decorated with dataclass_transform. From what I can tell, it is not.
I'd suggest filing an issue on flask_sqlalchemy.
I also want to point it out that when using unpacking syntax it doesn't raise any warnings or errors:
I think this is because there's no diagnostic when an unpacked dict contains extra fields that don't match parameters on the target function. For example:
params = {"foobar": 1}
user = User(**params) # no diagnostics
