`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 .