Execute ruff only on staged changes

[lexicalunit]

We want to start using ruff to prevent bad code from making it into future PRs while we work on fixing the issues that ruff surfaces about the entire codebase over time.

Is there a way to only run ruff on git staged changes rather than the entire source code?

[dhruvmanila]

I think you could use pre-commit (https://pre-commit.com/) to do it, but it'll still be scoped to the entire contents of all the staged files.

[charliermarsh]

I think @dhruvmanila is right that you could use pre-commit if you're only interested in running on changed files.

[evanrittenhouse]

I did find this snippet which may be able to help out. On mobile so not able to try it though - you'd probably need to fiddle around to change the command from eslint to ruff

[charliermarsh]

Ah yeah, unfortunately we don't support this right now, though it's come up a few times in different forms: #1149, #1931, #2696. I've generally been a bit hesitant to support it since it seems quite hard to get right.

[jstriebel]

Probably you are already aware of it, but the darker tool does exactly that for other formatters and linters. (Edit: Sorry, just found #2472 after posting this)

[itolosa]

I've tried to run ruff using darker like this:

darker -L "ruff check" . --check --diff

it seems to work fine @jstriebel

[HealthyPear]

Not really straightforward as having a direct option flag from ruff, but what about simply using git functionalities?

ruff check $(git diff --name-only --cached -- '*.py')

You can also do a similar thing on a CI pipeline over files changed via commits with respect to the master branch, for example in the case of a Merge Request pipeline on GitLab ,

ruff check $($(git diff --name-only $CI_MERGE_REQUEST_DIFF_BASE_SHA -- '*.py'))

[codethief]

If I have staged only some (not all) changes via git add -p, won't this touch the files in the working tree (as opposed to those in the staging area)?

[HealthyPear]

Maybe yes, the command above gives a list of files that have been added to the staging area; if you stage only a patch, that still comes from a file, so using something based on git diff might always result in the filename

maybe for that specific use case there is a better option

[dcdanielca]

This works perfectly:

git diff -u --relative --name-only | ruff check

git diff -u --relative --name-only | ruff format --check

This commands you can run with pre-commit or lefthook. For example lefthook.yml config:

pre-push:
  parallel: true
pre-commit:
  commands:
    ruff-linter:
      run: git diff -u --relative --name-only | ruff check
    run-format:
      run: git diff -u --relative --name-only | ruff format --check

[codethief]

I don't think this works as expected when you stage only patches, see my previous comment.