Is there a rule that always forces single line dictionaries?

[Kludex]

Like, I don't want this:

{
    "potato": "value",
    "key": "value",
}

I always want this:

{"potato": "value", "key": "value"}

Is there a rule for this?

[MichaReiser]

No, I don't think such rule exists. You can get this result when using ruff format (be warned, it applies many other formatting rules as well) when setting skip-magic-trailing-comma=true. But only if you're okay if it splits the dictionary over multiple lines if it exceeds the configured line length

[Kludex]

That will do. Thanks.

[Kludex]

Okay, sorry, I'm back. Let me refine my request...

I would like to try to enforce this if it's possible (max-length allows):

{"potato": "value", "key": "value"}

But then if it's not possible, I'd like to enforce this (multiline with trailing commas):

{
    "potato": "value",
    "key": "value",
}

I hate this:

{
    "potato": "value", "key": "value"
}

[MichaReiser]

You can use COM812 together with ruff format. COM812 adds a trailing comma after the second entry, the formatter then splits the dictionary across multiple lines (Playground)

However, this only works when not using skip-magic-trailing-comma. Otherwise, arguments might get formatted as

def test(
    aaaaaaa, bbbbbbbbbb, cccccccccccccc, dddddddddddddddddddddddddddddddddddddddddd
):
    pass

which is probably not to your taste ;)

However, if you use skip-magic-trailing-comma, then lines won't get collapsed if they now fit into the line length. There's currently no option that allows you to have both.