How to force nodejs script argument to take value from choices list using commander? - node.js

Question

I am using commander in node.js script. I am able to set default value to one argument.
var args = require('commander')
// set 'pending' as defaut value of status
args.option('-s --status <statusString>', 'Status to filter questions', 'pending').parse(process.argv)
console.log('status:', args.status)
How can I force status value to be from ["pending", "rejected", "accepted", "hold"] only? I did not find anything relevant in documention.

Answer 1

This is what I could achieve:
var options = ["pending", "rejected", "accepted", "hold"];
args.option(
'-s --status <statusString>',
`Status to filter questions: ${options}`,
function(val, _) {
if (!options.includes(val)) {
throw Error(`${val} is not from ${options}`);
}
return val;
},
'pending')
.parse(process.argv)
Not perfect, since you need to format help string and validate input value by yourself. Also, throwing an error from the validation function is not handled by Commander nicely and causes it to fail with the whole stacktrace in the output. I could not find a better way to tell Commander that the input is invalid.
In my case I finally just switched to argparse, which is a clone of the Python command line parser, and seems to be better thought over. This is how you limit choices with it:
const ArgumentParser = require('argparse').ArgumentParser;
const argparser = new ArgumentParser({ description: 'An example'});
argparser.addArgument('--status', {
choices: ['pending', 'rejected', 'accepted', 'hold'],
defaultValue: 'pending'});
const args = argparser.parseArgs();
This will do the job, including nice help message and input validation.

Answer 2

I think that in your case this is what you were looking for:
args
.addOption(
new Option('-s --status <statusString>', 'Status to filter questions')
.choices(["pending", "rejected", "accepted", "hold"])
.default('pending')
)
.parse(process.argv)
Also please take a look to another specific example I've prepared and tested successfully (NPM commander v8.2.0)
program
.addOption(
new Option('-s --status <statusString>', 'Status to filter questions')
.choices(["pending", "rejected", "accepted", "hold"])
.default('pending')
)
.action((args) => {
console.log(args)
})
Side note: please notice that for this second example I've used a slightly different naming convention for clarity: I've used program (vs original args) in the first line, as I was planning to use args name for the variable array received in the arrow function used in action() instead. Don't let that change confuse you! ;)
IMPORTANT: more on the official examples, direct link to a related example right here: https://github.com/tj/commander.js/blob/HEAD/examples/options-extra.js#L13