add JSON.parse support for arrayOfX

[ORESoftware]

I have this code which might allow me to use JSON strings as parseable option values

the syntax that works is:

--match='["a","b","c"]'

the patchwork code that I have added to my project looks like:

var parser = dashdash.createParser({ options: options });

var opts = parser.parse(process.argv);

console.log('opts before => ', util.inspect(opts));

options.filter(function (opt) {
  return String(opt.type).startsWith('arrayOf');  
}).forEach(function (opt) {

  const n = String(opt.name || opt.names[ 0 ]).replace('-', '_');
  if (n in opts) {
    opts[ n ] = _.flattenDeep(opts[ n ].map(function (item) {
      console.log('item => ', util.inspect(item));
      try {
        return _.flatten([ JSON.parse(item) ]);
      }
      catch (err) {
        return item;
      }
    }));
  }
});

console.log('opts after => ', util.inspect(opts));

but what I get is:

opts before =>  { match_any: [ '["dog","cat"]' ],
  errors_only: false,
  _order: [ { key: 'match_any', value: '["dog","cat"]', from: 'argv' } ],
  _args: [] }
item =>  '["dog","cat"]'
opts after =>  { match_any: [ 'dog', 'cat' ],
  errors_only: false,
  _order: [ { key: 'match_any', value: '["dog","cat"]', from: 'argv' } ],
  _args: [] }

looks like to make sure this goes bug free, that I would need library support for this, because the _order property needs to match I assume.

My best guess is for this type of support is to do:

  {
    names: [ 'match-any' ],
    type: 'arrayOfString',
    useJSON: true,
    help: 'Use this to filter input to match the given JS regex',
  },

if useJSON was true, then JSON.parse would be called for each item

[karfau]

JSON.parse would allow any content inside the string, be it undefined, null, a number, a single string, an object or an array (of any even mixed values of the above).

Since it's more then trivial to support a custom type json:

dashdash.addOptionType({
    name: 'json',
    takesArg: true,
    helpArg: 'JSON',
    parseArg: JSON.parse
});

or even arrayOfJson

dashdash.addOptionType({
    name: 'arrayOfJson',
    takesArg: true,
    array: true,
    //arrayFlatten: true, // depending on the needs
    helpArg: 'JSON[]',
    parseArg: JSON.parse
});

(Note: This code has not been tested!)

It makes more sense to leave related type/content checking to the specific script that uses dashdash.