DJRHails / PyMender

Perform entire codebase refactors in a way that is reproducible, testable and reviewable. Convert to FastAPI Annotated in one step.

👷‍♀️ PyMender

Perform entire codebase refactors in a way that is reproducible, testable and reviewable. Obeys .gitignore by default.

Usage

pip install pymender==0.2.0

pymender <codemod> <path_to_project>

What codemods are available?

⚡ FastAPIAnnotated

Converts FastAPI endpoints to use the preferred Annotated[<type>, Depends(<dependency>)] syntax rather than : <type> = Depends(<dependency>).

Why?

• Default value of the function parameter is the actual default value.
• Reuse of the function is now possible.
• Type-safe usage of the functions, previously 'default' values where not type checked.
• Multi-purpose e.g. Annotated[str, fastapi.Query(), typer.Argument()] is now possible.

pymender FastAPIAnnotated <folder-to-upgrade>

Before	After
@router.get('/example') def example_function( value: int, query: str = Query("foo"), zar: str = Query(default="bar", alias="z"), foo: str = Depends(get_foo), *, bar: str = Depends(get_bar), body: str = Body(...), ) -> str: return 'example'	@router.get('/example') def example_function( value: int, foo: Annotated[str, Depends(get_foo)], query: Annotated[str, Query()] = "foo", zar: Annotated[str, Query(alias="z")] = "bar", *, bar: Annotated[str, Depends(get_bar)], body: Annotated[str, Body()], ) -> str: return 'example'

Developer Guide

# Run a particular codemod
python3 -m pymender <codemod> <path_to_project>
# e.g.
python3 -m pymender FastAPIAnnotated <path_to_project>

# Run the codemod directly
python3 -m libcst.tool codemode fastapi_annotated.FastAPIAnnotated <path_to_project>

# Run tests
pytest -vv

Thanks to:

• libCST which does a lot of the hardwork for this.
• autotyping for showing what was possible.