Operator issue with sqlalchemy.func

[erictraut]

Operator issue with sqlalchemy.func

[erictraut]

@Apakottur, you asked whether this was a bug in the sqlalchemy stubs or in pyright. It appears to be a bit of both. I recommend filing a separate bug for the stubs issue.

[erictraut]

Here's a simplified code sample:

from datetime import timedelta
from sqlalchemy.sql.functions import current_date

def func(a: current_date, b: timedelta):
    reveal_type(a.__add__) # Appears not to bind correctly
    a.__add__(b)

    return a + b

[Azureblade3808]

It seems that there is a missing overload in SQLAlchemy.

For sqlalchemy.sql.elements.SQLCoreOperations, its __add__ method is declared as such --

        @overload
        def __add__(
            self: _SQO[_NMT],
            other: Any,
        ) -> ColumnElement[_NMT]: ...

        @overload
        def __add__(
            self: _SQO[str],
            other: Any,
        ) -> ColumnElement[str]: ...

        def __add__(self, other: Any) -> ColumnElement[Any]: ...

, whereas _SQO is an alias of SQLCoreOperations and _NMT is a type variable with a bound of float, int or Decimal. We can see that type of self in overloads doesn't cover everything including SQLCoreOperations[datetime.datetime] in the sample.

If the code above is modified with an additional overload --

        @overload
        def __add__(
            self: _SQO[_NMT],
            other: Any,
        ) -> ColumnElement[_NMT]: ...

        @overload
        def __add__(
            self: _SQO[str],
            other: Any,
        ) -> ColumnElement[str]: ...

        # Added.
        @overload
        def __add__(self, other: Any) -> ColumnElement[Any]: ...

        def __add__(self, other: Any) -> ColumnElement[Any]: ...

, no error gets reported.

But I think the error message could be improved and the method should be uncallable in its current form.

[erictraut]

Good analysis. I agree that the error message could be improved. I also think a.__add__ should generate an error since __add__ cannot be bound to a.

[Apakottur]

Opened a PR to fix the types, if it wont get accepted I'll open an issue.

[erictraut]

This is addressed in pyright 1.1.360, which I just published.