Cannot override index=True with mapped_column in Annotated

[zzzeek]

Discussed in #11090

^{Originally posted by decardev March 4, 2024}
Cannot override mapped_column(index=True) when using Annotated

python 3.12
OK: OSX
sqlalchemy: 2.0.27

The documentation states:

The mapped_column() construct is also reconciled with an explicitly passed mapped_column() construct, whose arguments will take precedence over those of the Annotated construct. Below we add a ForeignKey constraint to our integer primary key and also use an alternate server default for the created_at column:

But the following produces an indexe for fail.

from typing import Annotated

from pydantic.dataclasses import dataclass
from sqlalchemy import Integer, inspect
from sqlalchemy.orm import DeclarativeBase, Mapped, MappedAsDataclass, mapped_column


class Base(MappedAsDataclass, DeclarativeBase, dataclass_callable=dataclass):
    pass


IdField = Annotated[int, mapped_column(Integer, index=False)]
IdFieldIndexed = Annotated[int, mapped_column(Integer, index=True)]


class Model(Base):
    __tablename__ = "model"
    id: Mapped[int] = mapped_column(Integer, primary_key=True, default=1)
    ok_default: Mapped[IdField] = mapped_column(default=1)
    ok_overrides_false: Mapped[IdField] = mapped_column(index=True, default=1)

    fail: Mapped[IdFieldIndexed] = mapped_column(index=False, default=1)


# mapped_column does not override the index parameter of the Annotated type when True. 
{name: col.expression.index for name, col in inspect(Model).column_attrs.items()}
```</div>

[sqla-tester]

Mike Bayer has proposed a fix for this issue in the main branch:

accommodate False conditions for unique / index merge https://gerrit.sqlalchemy.org/c/sqlalchemy/sqlalchemy/+/5178

[sqla-tester]

Mike Bayer has proposed a fix for this issue in the rel_2_0 branch:

accommodate False conditions for unique / index merge https://gerrit.sqlalchemy.org/c/sqlalchemy/sqlalchemy/+/5179