Variadic option support

[arkgast]

I'm trying to use an option with multiple arguments and the behavior I'm having is not what I could expect according to Commander variadic option section where the parsed option is an array.

The current behavior is that I'm getting just the last option. But all options pass through parseOptions method.

import { Command, CommandRunner, Option } from "nest-commander";

@Command({ name: 'command', options: { isDefault: true } })
export class BasicCommand implements CommandRunner {
  async run(args: string[], options: any): Promise<void> {
    console.log({ args, options })
  }

  @Option({
    flags: '-o, --opts [options...]',
    description: 'Multiple options',
  })
  parseOptions(options: string) {
    console.log({ options })
    return options
  }
}

node dist/main -o opt1 opt2 opt3
{ options: 'opt1' }
{ options: 'opt2' }
{ options: 'opt3' }
{ args: [], options: { opts: 'opt3' } }

Not sure if I'm doing something wrong or this might be a bug.

[jmcdo29]

Oh interesting that that method gets called per passed option and not with all of them at once. I may need to modify some code to take care of that. Could you provide me a small minimum reproduction so I can better track this down?

[arkgast]

Sure thing @jmcdo29.

Here you can find a small demo with the behavior I explained above.

[jmcdo29]

Awesome. Thank you for this. So I was looking into how commander itself handles a situation like this, and it seems that the callback handler for options is actually like so:

option<T>(flags: string, description: string, fn: (value: string, previous: T) => T, defaultValue?: T): this;

Looking at this, we can type our custom decorated methods like so:

  @Option({
    flags: '-o, --opts [options...]',
    description: 'Multiple options',
  })
  parseOptions(option: string, options: string[] = []) {
    console.log('parseOptions: ', { option })
    options.push(option)
    return options
  }

And now we get the desired output

parseOptions:  { option: 'opt1' }
parseOptions:  { option: 'opt2' }
parseOptions:  { option: 'opt3' }

running command with next args and opts:
{ args: [], options: { opts: [ 'opt1', 'opt2', 'opt3' ] } }

You can view the forked REPL here

I'm not sure if there's something we should do at the library level, as wrapping already custom methods in our own methods could get messy, so I think the best approach here would be to document that this is how to handle variadic options. What are your thoughts @arkgast?

[arkgast]

Yes, I agree.
I was bit confused about how it could be used, now it's clear. Thanks!

[jmcdo29]

Cool, I'll update the docs for this then so it's clear for others. Seems there's no changes necessary to the library