Optional argument in command with click

Question

I am trying to accomplish something not very standard for CLI parsing with Click and it only works partially:

main CLI has multiple sub-commands (in sample below 'show' and 'check')
both those commands might have optional argument, but the argument is preceding them not following
I decided to handle that argument in the group "above" it and pass the value in the context

Sample:

import click

@click.group()
@click.argument('hostname', required=False)
@click.pass_context
def cli(ctx, hostname=None):
    """"""
    ctx.obj = hostname
    click.echo("cli: hostname={}".format(hostname))

@cli.command()
@click.pass_obj
def check(hostname):
    click.echo("check: hostname={}".format(hostname))

@cli.command()
@click.pass_obj
def show(hostname):
    click.echo("check: hostname={}".format(hostname))

if __name__ == '__main__':
    cli()

The part WITH the hostname works:

> pipenv run python cli.py  localhost check
cli: hostname=localhost
check: hostname=localhost
> pipenv run python cli.py  localhost show
cli: hostname=localhost
check: hostname=localhost

But the part WITHOUT the hostname DOES NOT:

> pipenv run python cli.py show
Usage: cli.py [OPTIONS] [HOSTNAME] COMMAND [ARGS]...

Error: Missing command.

Anybody has an idea about the direction I should start looking into?

Optional argument in command with click

1 Answers