How to specify flow level of a specific element?

[njourdane]

I have this data:

{
  "dict": [
    {
      "foo": [
        "bar"
      ]
    }
  ],
  "array": [
    [1, 2, 3, 4, 5],
    [6, 7, 8, 9, 10]
  ]
}

And I would like dump it like this:

dict:
- foo:
  - bar
arrays:
- [1, 2, 3, 4, 5]
- [6, 7, 8, 9, 10]

Ie. indent all elements except array items.

I know I can use flowLevel to specify level of nesting, but how to apply it only for one item in data?

[rlidwka]

Not possible at the moment (unless you want to employ excessive amounts of hacking).

We can't add this option, because people are asking for dozens (if not hundreds) of these, and adding every one of them would bloat dumper API too much.

Any ideas for custom formatting perhaps?

[rlidwka]

closing as duplicate of #586

[rlidwka]

just like in the ticket above, here's a hacky solution which you can use at your own risk:

const yaml = require('js-yaml');

function CustomDump(data, opts) {
  if (!(this instanceof CustomDump)) return new CustomDump(data, opts);
  this.data = data;
  this.opts = opts;
}

CustomDump.prototype.represent = function () {
  let result = yaml.dump(this.data, Object.assign({ replacer, schema, noArrayIndent: true }, this.opts));
  result = result.trim();
  if (result.includes('\n')) result = '\n' + result;
  return result;
}


let CustomDumpType = new yaml.Type('!format', {
  kind: 'scalar',
  resolve: () => false,
  instanceOf: CustomDump,
  represent: d => d.represent()
});


let schema = yaml.DEFAULT_SCHEMA.extend({ implicit: [ CustomDumpType ] });

function replacer(key, value) {
  if (key === '') return value; // top-level, don't change this
  if (Array.isArray(value) && value.length > 4) return CustomDump(value, { flowLevel: 0 });
  return value; // default
}

console.log(CustomDump(
{
  "dict": [
    {
      "foo": [
        "bar"
      ]
    }
  ],
  "array": [
    [1, 2, 3, 4, 5],
    [6, 7, 8, 9, 10]
  ]
}
).represent().trim());

/* Returns:

dict:
- foo:
  - bar
array:
- [1, 2, 3, 4, 5]
- [6, 7, 8, 9, 10]
*/