Option that is not required and prompts if specified without an arg

[johnksterling]

Hi -

I am working on a ticket for mycli - the gist is that the team wants the '-p' flag to behave like th e mysql client - i.e. prompt if you don't pass an arg, but it is not required so do NOT prompt if the -p is not included. Today if I use standard click->prompt then scenario 2 gives an error. Below is the desired behavior:

1. $> ./hello
   HELLO WORLD
2. $> ./hello -p
   Please enter your password:
3. $> ./hello -p s3cr3t
   HELLO WORLD

It appears looking at the code there is no way to do this, but it seems desirable - before working on a PR I wanted to validate that it can't be done and get input on the usefulness of the feature.

Thanks for your guidance
John

[fdavis]

Thanks for your feedback!

I don't see anyway to do that currently but it definitely seems like a good use case to me.
I think we may need a new option for intance prompt_required to help disambiguate this behavior from the required option behavior

import click

@click.command()
@click.option('--username')
@click.option('-p', '--password', prompt=True, prompt_required=False, hide_input=True)
def echoing(username, password):
    click.echo(username)
    click.echo(password)

echoing()

[reinaldorauch]

@fdavis I understand where comes from you line of thought but wouldn't be better, semantically speaking, if we create a promp_when_not_declared to evidentiate the current behavior?

Using your example:

import click

@click.command()
@click.option('--username')
# Keeps the current behavior
@click.option('-p', '--password', prompt=True, prompt_when_not_declared=True, hide_input=True)
# Prompts only if passed as argument to the command, maybe change this to be the default, I say why below
@click.option('-p', '--password', prompt=True, prompt_when_not_declared=False, hide_input=True)
def echoing(username, password):
    click.echo(username)
    click.echo(password)

echoing()

When I was reading the docs I was carried to understand that as it is an option, it would only prompt if the option was passed to the command, but it prompts always.

[amy-lei]

I'll be working on this issue! Just to clarify:

1. Should the default be prompt_required=True? From the examples in the doc, it seems like this should be the case. But as reinaldorauch mentions, I would've assumed the opposite since it's an option.
2. Should the option act as a flag regardless of whether prompt_required is True or False? As of now, running hello -p raises the error Error: -p option requires an argument rather than prompting the user for a value. Or should we keep this behavior for when prompt_required=True

[amy-lei]

Discussed with @juped and thought the default should be True to maintain the current behavior of prompts. Then for a similar reason, options should only act as a flag when prompt_required=False and raise an error otherwise.