Prompting users for input

August 10, 2019
This post is part of the "Building CLI Apps with Python" series.


Getting user input is an important part of any kind of application. Since we've already learned about options, adding a user prompt to our hello world app should be a breeze. All we need to do is add prompt=True to the option decorator, so that it prompts the user for input if no option is passed in.

# helloworld.py

import click

@click.command()
@click.option('-c', '--case',
              type=click.Choice(['upper', 'lower']),
              prompt=True)
@click.argument('person', default='you')
def hello(case, person):
    response = "Hello World! Also, hey {} ☺️".format(person)
    if case == 'upper':
        click.echo(response.upper())
    elif case == 'lower':
        click.echo(response.lower())
    else:
        click.echo(response)

Save and run the app:

(venv) $ hello
Case (upper, lower): upper
HELLO WORLD! ALSO, HEY YOU ☺️

(venv) $ hello sally
Case (upper, lower): lower
hello world! also, hey sally ☺️

You may also set a custom prompt string if you wish:

# helloworld.py

import click

@click.command()
@click.option('-c', '--case',
              type=click.Choice(['upper', 'lower']),
              prompt='Please enter case')
@click.argument('person', default='you')
def hello(case, person):
    response = "Hello World! Also, hey {} ☺️".format(person)
    if case == 'upper':
        click.echo(response.upper())
    elif case == 'lower':
        click.echo(response.lower())
    else:
        click.echo(response)

The set string will now be displayed instead of the default prompt:

(venv) $ hello
Please enter case (upper, lower): upper
HELLO WORLD! ALSO, HEY YOU ☺️


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