ruff format doesn't sort imports, leaves file unchanged

[alexei]

I'm looking into using ruff (0.1.6 on Python 3.12) for formatting and... it doesn't appear to be doing anything, at least in terms of replicating isort behaviour.

Input

from _common import foo
import dataclasses as dc
import psycopg
from typing import Any
import hashlib
from foo.bar import baz
from functools import partial
from time import monotonic
from enum import Enum, auto
from uuid import UUID

Command

$ python -m ruff format -v ./test_ruff.py
[2023-11-30][15:29:28][ruff_cli::resolve][DEBUG] Using Ruff default settings
[2023-11-30][15:29:28][ruff_cli::commands::format][DEBUG] format_path; path=.../test_ruff.py
[2023-11-30][15:29:28][tracing::span][DEBUG] Printer::print;
[2023-11-30][15:29:28][ruff_cli::commands::format][DEBUG] Formatted 1 files in 191.92µs
1 file left unchanged

Expected result

import dataclasses as dc
from enum import Enum, auto
from functools import partial
import hashlib
from time import monotonic
from typing import Any
from uuid import UUID

import psycopg

from _common import foo
from foo.bar import baz

Or something like that.

Actual result

The file is unchanged.

---

What am I missing?

[charliermarsh]

In Ruff, import sorting and re-categorization is part of the linter, not the formatter. The formatter will re-format imports, but it won't rearrange or regroup them, because the formatter maintains the invariant that it doesn't modify the program's AST (i.e., its semantics and behavior).

To get isort-like behavior, you'd want to run ruff check --fix with --select I or adding extend-select = ["I"] to your pyproject.toml or ruff.toml.

[zanieb]

See also #8087, #8612, and #8367

[alexei]

Got it, thanks!

[Hubro]

While the rationale makes complete sense, this does make it pretty awkward and unintuitive to sort import statements as part of auto-formatting in editor configs and such. Would it be a possibility to add a shortcut for this as a flag to ruff format, just as a UX improvement?

--sort-imports
    Sort imports after formatting, equivalent to running `ruff check --fix --select I`

[alexei]

I agree it sounds technically correct, but a little awkward from a practical standpoint. When I need to format the code, I use a script that runs:

ruff check . --select I --fix
ruff format .

[ruslaniv]

To get isort-like behavior, you'd want to run ruff check --fix with --select I or adding extend-select = ["I"] to your pyproject.toml or ruff.toml.

I have added

[tool.ruff.lint]
extend-select = ["I"]

to pyproject toml, so now when running

ruff check --fix config.py

I get

config.py:37:1: E402 Module level import not at top of file
Found 1 error.

but nothing gets resorted in the file.
How do I tell ruff to actually physically resort the imports in the file just like iSort does

[alexei]

@ruslaniv have you tried select instead of extend-select?

[ruslaniv]

Yes, just tried it

[tool.ruff.lint]
select = ["I"]

and in this case it's not even picking up the error:

ruff check --fix config.py           
All checks passed!

[MichaReiser]

@ruslaniv please consider creating a new issue, ideally with minimal repro.

Can you try running ruff check config.py --show-settings to see what rules are selected?

[gboeer]

EDIT: In my case, I just forgot to commit the pyproject.toml after having added the ruff settings (e.g. to do import sorting). After committing the pyproject.toml the subsequent linting/sorting errors get caught and reformatted as expected in my pre-commit.

I can add a similar observation to this. Having a simple file like:

from pathlib import Path
import os

print(Path(os.getcwd()))

and a pyproject.toml entry:

[tool.ruff.lint]
select = ["I"]

The cli command behaves as expected:

ruff check temp.py
temp.py:1:1: I001 [*] Import block is un-sorted or un-formatted
Found 1 error.
[*] 1 fixable with the `--fix` option.

And will correctly fix the import statement when I add --fix

However, in my pre-commit hook the file will not be fixed but accepted as is (with the wrongly ordered inputs).

My pre-commit is configured as:

- repo: https://github.com/astral-sh/ruff-pre-commit
  # Ruff version.
  rev: v0.3.5
  hooks:
    # Run the linter.
    - id: ruff
      args: [ --fix ]
    # Run the formatter.
    - id: ruff-format

[charliermarsh]

@gboeer - This sounds similar to astral-sh/ruff-pre-commit#64 -- perhaps chime in there?

[zhou13]

This issue causes some inconvenience using the sorting functionality:

• It is intuitive to think ruff format will help you reorder (i.e., format) the import, rather than using ruff check --fix;
• While it might be not true, but I would imagine that ruff check --fix might be somehow dangerous and thus hesitant to run it too often. However, sorting the import should be saf enough to run on every file save in IDE.
• This makes isort function from ruff lsp-server awkward to use in many IDEs:
  • Normally, IDE has an option like format_on_save using LSP, so it is very easy to run ruff format in your IDE;
  • To sort the import, one needs to run a code action. This takes more keystrokes, and it is much harder to configure to run it with format_on_save in general.

I do understand that currently import sorting and re-categorization is implemented as the linter, not the formatter, which might make sense in terms of the function group. But as a user, I think the software UI ergonomics is more important here.