This codemod replaces typing.Optional[T] by typing.Union[T, None] in the codebase.

This tool was inspired by a tweet from Sebastián Ramírez (as you see below), and a conversation between us.

As the tweet says, we have two reasons for doing this:

1. It's more explicit to write Union[str, None] than Optional[str]. Mainly because Optional[str] doesn't mean that the attribute is optional. It only means that it accepts None as a possible value.
2. On Python 3.10+ you can type annotate as str | None instead of the above two. Which is more similar to Union[str, None] than Optional[str].

pyupgrade is great but no-optional is better when you need runtime support like for FastAPI and pydantic.

The reason being that no-optional just does the replacement. On the other hand, pyupgrade requires from __future__ import annotations for versions below Python 3.10.

pip install no-optional

Run the following on the repository you want to format:

python -m no_optional <files>

You can also use the pre-commit. Add the following to your .pre-commit-config.yaml file:

  - repo: https://github.com/Kludex/no-optional
    rev: 0.4.0
    hooks:
      - id: no_optional

This project is licensed under the terms of the MIT license.