[FEATURE] Pattern matching on Argument

[fproulx-boostsecurity]

The solution you would like

I would like to specify a pattern (regex) to limit the valid patterns for an argument

[daddycocoaman]

You can accomplish this with a callback.

import re
import typer

app = typer.Typer()


def regex_match(value):
    regex = r"^fan"
    if re.match(regex, value):
        return value
    raise typer.BadParameter(f"Does not match the regex: {regex}")


@app.command()
def print_word(word: str = typer.Argument(..., callback=regex_match)):
    typer.echo(f"Your valid string is: {word}")


if __name__ == "__main__":
    app()

python typerre.py amazing                                                                                   
Usage: typerre.py [OPTIONS] WORD

Error: Invalid value for 'WORD': Does not match the regex: ^fan

python typerre.py fantastic                                                                    
Your valid string is: fantastic

[MexHigh]

You can accomplish this with a callback.

Additionally, you could nest a callback function in another function, so you only need one for arbitrary regex:

import re
import typer

app = typer.Typer()


def regex_match(regex):
    def callback(value):
        if re.match(regex, value):
            return value
        raise typer.BadParameter(f"Does not match {regex}")
    return callback


@app.command()
def print_word(word: str = typer.Argument(
    ..., 
    callback=regex_match(r"^fan")
)):
    typer.echo(f"Your valid string is: {word}")


if __name__ == "__main__":
    app()

[YuriiMotov]

This way (implementation with callback) it will not be shown in the help.