Using a numeric identifier for value selection in click.Choice - python-click

Question

The Click package allows a range of values to be selected from a list using the click.Choice method.
In my case the values are relatively long strings, so using:
choice_names = [u'Vulnerable BMC (IPMI)', u'IoT Vulnerability', u'SMBv1', u'BadHTTPStatus', u'Compromised']
#click.option('--category', prompt='\nPlease enter the category of incident.\n\n -- Options:\n{}\n\n'.format(
format_choices(choice_names)), type=click.Choice(choice_names))
will list the values as:
-> Vulnerable BMC (IPMI)
-> IoT Vulnerability
-> SMBv1
-> BadHTTPStatus
-> Compromised
This requires the user to enter the full string, which is inconvenient. Does Click provide a functionality to select a value using only a numeric identifier? So, the above options could be listed as:
-> Vulnerable BMC (IPMI) [1]
-> IoT Vulnerability [2]
-> SMBv1 [3]
-> BadHTTPStatus [4]
-> Compromised [5]
and to select the first option, the user would need to enter 1. This could be possible by defining a custom validation function, but I couldn't find any existing functionality offered by Click.

Answer 1

I came up with this:
class ChoiceOption(click.Option):
def __init__(self, param_decls=None, **attrs):
click.Option.__init__(self, param_decls, **attrs)
if not isinstance(self.type, click.Choice):
raise Exception('ChoiceOption type arg must be click.Choice')
if self.prompt:
prompt_text = '{}:\n{}\n'.format(
self.prompt,
'\n'.join(f'{idx: >4}: {c}' for idx, c in enumerate(self.type.choices, start=1))
)
self.prompt = prompt_text
def process_prompt_value(self, ctx, value, prompt_type):
if value is not None:
index = prompt_type(value, self, ctx)
return self.type.choices[index - 1]
def prompt_for_value(self, ctx):
# Calculate the default before prompting anything to be stable.
default = self.get_default(ctx)
prompt_type = click.IntRange(min=1, max=len(self.type.choices))
return click.prompt(
self.prompt, default=default, type=prompt_type,
hide_input=self.hide_input, show_choices=False,
confirmation_prompt=self.confirmation_prompt,
value_proc=lambda x: self.process_prompt_value(ctx, x, prompt_type))
#click.command()
#click.option('--hash-type', prompt='Hash', type=click.Choice(['MD5', 'SHA1'], case_sensitive=False), cls=ChoiceOption)
def cli(**kwargs):
print(kwargs)
Result:
> cli --help
Usage: cli [OPTIONS]
Options:
--hash-type [MD5|SHA1]
--help Show this message and exit.
> cli --hash-type MD5
{'hash_type': 'MD5'}
> cli
Hash:
1: MD5
2: SHA1
: 4
Error: 4 is not in the valid range of 1 to 2.
Hash:
1: MD5
2: SHA1
: 2
{'hash_type': 'SHA1'}
Edit May 25, 2020:
I recently came across questionary and integrated it with click
import click
import questionary
class QuestionaryOption(click.Option):
def __init__(self, param_decls=None, **attrs):
click.Option.__init__(self, param_decls, **attrs)
if not isinstance(self.type, click.Choice):
raise Exception('ChoiceOption type arg must be click.Choice')
def prompt_for_value(self, ctx):
val = questionary.select(self.prompt, choices=self.type.choices).unsafe_ask()
return val
#click.command()
#click.option('--hash-type', prompt='Hash', type=click.Choice(['MD5', 'SHA1'], case_sensitive=False), cls=QuestionaryOption)
def cli(**kwargs):
print(kwargs)
if __name__ == "__main__":
cli()

Answer 2

Since Click does not seem to provide a functionality of this kind, this custom validation function fulfills the purpose:
def validate_choice(ctx, param, value):
# Check if the passed value is an integer.
try:
index = int(value) - 1
# Return the value at the given index.
try:
return choice_names[index]
# If the index does not exist.
except IndexError:
click.echo('Please select a valid index.')
# If the value is of a different type, for example, String.
except (TypeError, ValueError):
# Return the value if it exists in the list of choices.
if value in choice_names:
return value
else:
click.echo('Please select a valid value from the choices {}.'.format(choice_names))
# Prompt the user for an input.
value = click.prompt(param.prompt)
return validate_choice(ctx, param, value)
#click.option('--category', prompt='\nPlease enter the category.\n\n -- Options:\n{}\n\n'.format(choice_names),
help='Category of the incident', callback=validate_category)
This allows a user to select a choice either by entering the choice name or by entering the index value. In case an invalid value is entered, the user is prompted again for an input.