Using Mapped[str | None]

[Peter Schutt]

Hi,

I've been using 2.0 from main and notice that annotating an attribute with `mapped[str | None]` raises with:

sqlalchemy.exc.ArgumentError: Could not locate SQLAlchemy Core type for Python type: str | None

I've been able to get it to work with a couple of mods in util.typing and orm.properties and the basic tox run doesn't show any failures.

I've searched both GH issues and in the group here for that exception string without result, is this worth opening an issue for?

Thanks!

[Mike Bayer]

you should be using Mapped[Optional[str]] ; that said if Mapped[Union[str, None]] and/or Mapped[str | None] is not being parsed then yes this is worthy of a bug report for 2.0.

Thanks!

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[Peter Schutt]

Thanks Mike, I will submit at next opportunity.

I believe Union[str, None] is fine, just that pep 604 brought in UnionType in 3.10+ which represents the "str | None" union type, but I'll stick more detail in the issue.

Not having to import Optional or Union everywhere is one of the nice ergonomic improvements to typing of late.

Cheers:)

[Mike Bayer]

absolutely, there's no reason str | None shouldn't work also

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