[QUESTION] How to automatically validate input parameter as IPv4Address

[johnthagen]

First check

• I used the GitHub search to find a similar issue and didn't find it.
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• I already searched in Google "How to X in Click" and didn't find any information.

Description

With argparse it it possible to do something like:

    parser.add_argument(
        "--host",
        type=IPv4Address,
        default=IPv4Address("127.0.0.1"),
    )

This will automatically try to construct a IPv4Address type from the input and validate that it is a valid IPv4Address.

$ main.py --host=a
...
main.py: error: argument --host: invalid IPv4Address value: 'a'

I didn't see this type documented in typer. Is this possible to do?

[johnthagen]

Perhaps this should be a feature request.

@app.command()
def main(
    host: IPv4Address = typer.Option(
        IPv4Address("127.0.0.1"), help="Host interface to listen on."
    ),
) -> None:
    pass

Output when run:

RuntimeError: Type not yet supported: <class 'ipaddress.IPv4Address'>

[daddycocoaman]

In the meantime, you can get use the callback parameter to call IPv4Address. If it's valid, cool. If not, it'll error.

@app.command()
def main(host: stre= typer.Option("127.0.0.1", help="Host interface to listen on.", callback=IPv4Address)) -> None:
    pass

[johnthagen]

@daddycocoaman Thanks, this is close to what I was looking for. The callback=IPv4Address does what I expect, but then the type hint is incorrect. It is type hinted as str but what is actually passed in the host variable is of type IPv4Address. Ideally, for type checking and better editor integration, we'd like them to match.

[baterflyrity]

+1, I need this feature in 99% of cli projects.

[baterflyrity]

@johnthagen , unfortunately, click (basic library) seem to not support IPv4Address type. So guess we need to request this type on click's issue tracker.

p.s.
As you can see types are just mapped to underlying library ones.

[daddycocoaman]

Looks like creating new Click types isn't that difficult either, although it seems that the Click team isn't always open integrating new types. This guy tried to get Date merged into Click and it was rejected. pallets/click#1655 It might be worth creating an additional package for extra click types that Typer can import, or building on the existing project for additional parameters. https://github.com/click-contrib/click_params

…

On Wed, Mar 3, 2021, 7:29 AM baterflyrity ***@***.***> wrote: @johnthagen <https://github.com/johnthagen> , unfortunately, click (basic library) seem not to support IPv4Address type. So guess we need to request this type on click's issue tracker. p.s. As you can see <https://github.com/tiangolo/typer/blob/c3a4c72a4f1a18b7f16addb508862ec63411fa63/typer/main.py#L503> types are just mapped to underlying library ones. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#239 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AFBVEI6JLLRUE4IJEZPET3TTBYTQ3ANCNFSM4YEPGLKQ> .

[YuriiMotov]

You can make IPv4Address (and other custom types) working by specifying parser parameter:

from ipaddress import IPv4Address

import typer
from typing_extensions import Annotated

def main(
    host: Annotated[
        IPv4Address,
        typer.Argument(
            parser=IPv4Address,
            default_factory=lambda: IPv4Address("127.0.0.1"),
            help="Host address (IP v4)",
            show_default="127.0.0.1",
        ),
    ],
):
    print(f"host is {host}")

if __name__ == "__main__":
    typer.run(main)

Docs: https://typer.tiangolo.com/tutorial/parameter-types/custom-types/