Running black only on committed python files

Question

I am just trying to use precommit as a git hook on my python project. What I want to do is to run black only on the committed files. I am also running black through poetry.

At the moment my config looks like:

fail_fast: true
repos:
  - repo: local
    hooks:
      - id: system
        name: Black
        entry: poetry run black .
        pass_filenames: false
        language: system

This, of course, runs black on the whole project structure and this is not what I want.

Is it possible to just run black on the committed files.

score 4 · Accepted Answer · answered Oct 15 '22 at 20:13

4

If you are not constrained by using poetry, you can use the following that will solve your purpose:

  - repo: https://github.com/psf/black
    rev: 22.6.0
    hooks:
      - id: black
        language_version: python3.9 # Change this with your python version
        args:
          - --target-version=py39 # Change this with your python version

This will respect any and all settings you may have defined in pyproject.toml.

answered Oct 15 '22 at 20:13

Manas Sambare

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1

hmmmmm but will this run black only on committed files? – Luca Oct 15 '22 at 20:26
1

this is indeed the supported way to run `black` through pre-commit - the pre-commit author – anthony sottile Oct 15 '22 at 21:13
1

Yes @Luca, it will run black only on the committed files. – Manas Sambare Oct 15 '22 at 22:42

score 1 · Answer 2 · answered Nov 23 '22 at 15:17

This will work.

fail_fast: true
repos:
  - repo: local
    hooks:
      - id: black
        name: Black
        entry: poetry run black
        language: system
        types: [file, python]
        stages: [commit]

Explanation:

Remove pass_filenames: false to use the default true.
Remove . from the poetry run black command. When pre-commit runs it will append the file names to the end. I.e: poetry run black file1 file2 file3
Specify the file types.
Optional: specify the stage.

Running black only on committed python files

2 Answers2