How to handle sub-group help message

Question

I am trying to understand some implementation details about Click. I have the following example code:

#cli.py

import click


@click.group()
def cli():
    pass


@cli.group()
def show():
    """ Define the environment of the product """
    pass


@show.command()
def name():
    click.echo("run show name command")


@show.command()
def height():
    click.echo("run show height command")


if __name__ == "__main__":
    cli()

With this code, name and height are sub-commands of the show group. However, semantically, that doesn't really make sense. They are more so arguments of a 'show' command.

I know I can have a command with an "attribute" argument from which I can call a different function based on the string value of "attribute." However, I feel that would get tedious to maintain once there are several possibilities for "attribute."

I believe I could still use the above structure if I were able to edit the help message. When I run cli.py show --help, I get the default help message for a command group:

Usage: cli.py show [OPTIONS] COMMAND [ARGS]...

  Define the environment of the product

Options:
  --help  Show this message and exit.

Commands:
  height
  name

Is there a way to edit the help message to change "Commands" to "Arguments"? I know how to change the usage statement in the click.group() decorator, but I'm not sure how to modify the help message itself.

The help message I would like to achieve is as follows:

Usage: cli.py show [OPTIONS] ARG

  Define the environment of the product

Options:
  --help  Show this message and exit.

Arguments:
  height
  name

Is something like this possible?

I'm using python3 and Click 6.7

Answer 1

You can change the message given by the sub commands help, by using a custom class for the group. The custom class can be made by inheriting from click.Group and changing the format_commands() method like:

Custom Class:

class HelpAsArgs(click.Group):
    # change the section head of sub commands to "Arguments"

    def format_commands(self, ctx, formatter):
        rows = []
        for subcommand in self.list_commands(ctx):
            cmd = self.get_command(ctx, subcommand)
            if cmd is None:
                continue

            help = cmd.short_help or ''
            rows.append((subcommand, help))

        if rows:
            with formatter.section('Arguments'):
                formatter.write_dl(rows)

Test Code:

import click

@click.group()
def cli():
    pass

@cli.group(cls=HelpAsArgs)
def show():
    """ Define the environment of the product """
    pass

@show.command()
def name():
    click.echo("run show name command")

@show.command()
def height():
    click.echo("run show height command")

if __name__ == "__main__":
    commands = (
        'show',
        'show --help',
        '--help',
    )

    import sys, time

    time.sleep(1)
    print('Click Version: {}'.format(click.__version__))
    print('Python Version: {}'.format(sys.version))
    for command in commands:
        try:
            time.sleep(0.1)
            print('-----------')
            print('> ' + command)
            time.sleep(0.1)
            cli(command.split())

        except BaseException as exc:
            if str(exc) != '0' and \
                    not isinstance(exc, (click.ClickException, SystemExit)):
                raise

Results:

Click Version: 6.7
Python Version: 3.6.3 (v3.6.3:2c5fed8, Oct  3 2017, 18:11:49) [MSC v.1900 64 bit (AMD64)]
-----------
> show
Usage: test.py show [OPTIONS] COMMAND [ARGS]...

  Define the environment of the product

Options:
  --help  Show this message and exit.

Arguments:
  height
  name
-----------
> show --help
Usage: test.py show [OPTIONS] COMMAND [ARGS]...

  Define the environment of the product

Options:
  --help  Show this message and exit.

Arguments:
  height
  name
-----------
> --help
Usage: test.py [OPTIONS] COMMAND [ARGS]...

Options:
  --help  Show this message and exit.

Commands:
  show  Define the environment of the product