✨ Allow annotated parsing with a subclass of Path

[emfdavid]

Please allow using custom Path subclasses such as UPath

Here is an example

import logging
from pathlib import Path
from typing import Annotated, Optional

import typer
from upath import UPath
app = typer.Typer()

@app.command()
def path_func(arg: Annotated[UPath, typer.Argument(parser=UPath)]):
    logger.info(f"got arg: '{arg}'; type: {type(arg)}")

if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO)
    logger = logging.getLogger(__name__)
    app()

But as you can see in my debugger, the parsed value will get converted to a Path by the param_path_convertor.

Allowing that function to return anything that is already a Path (or maybe a PurePath?) would fix this issue, though, it maybe a problem for other types as well?

I can hack around this by setting the annotated type to None but using UPath as a parser, however that does not seem to be documented behavior or good practice.

@app.command()
def path_func(arg: Annotated[None, typer.Argument(parser=UPath)]):
    logger.info(f"got arg: '{arg}'; type: {type(arg)}")

[svlandeg]

Hi, thanks for the contribution and feature request!

What you're proposing makes sense to me, and at a first glance the code looks good. Surprisingly, some of the CI tests do fail. Do you have time to look into those?

[emfdavid]

Well - that was a rabbit hole.
Let's see if my hack works for older versions of python... if not can we just skip this test for older versions?

[emfdavid]

@svlandeg what happens now?

[svlandeg]

@svlandeg what happens now?

@emfdavid: we've put this on our internal reviewing board, but we're currently facing quite a bit of a backlog in PRs (also on fastapi etc), so it may take a while before we make a final decision. We'll keep you up-to-date here!

[emfdavid]

@emfdavid: we've put this on our internal reviewing board, but we're currently facing quite a bit of a backlog in PRs (also on fastapi etc), so it may take a while before we make a final decision. We'll keep you up-to-date here!

Thank you for the update - I have monkey patched my applications for now.

[delsner]

@svlandeg any idea when this will land? Thanks!

[svlandeg]

@delsner & @emfdavid : I've been engaged on other projects for the last few months, but I'll try and review this in detail this week! Thanks for your patience 🙏

[svlandeg]

This is a nice fix that supports subclassing Path cleanly. I verified that the test fails on master and otherwise everything looks good to me.

I'll leave this for Tiangolo for a final check.

Thanks again for your work on this, @emfdavid!

[tiangolo]

Awesome, makes sense, thank you @emfdavid! 🚀

I can see how figuring out Python < 3.12 was probably hard with the _flavor stuff. 😅

Thanks @svlandeg for the review and help! 🎉

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This will be available in Typer 0.17.3 in the next minutes. 😎