Group Values in JSONata

Question

Is there a possibility to group items by a specific attribute via JSONata

For example grouping following json by the values form the resultDate.

"Export": [
  {
    "code": "18724-100",
    "resultDate": "11.03.2018 13:11:48"
  },
  {
    "code": "18724-5",
    "resultDate": "11.03.2018 13:11:48"
  },
  {
    "code": "18724-99",
    "resultDate": "14.03.2018 14:11:48"
  }
]

To generate the following output:

"Export": [
  {
    "resultDate": "11.03.2018 13:11:48",
    "codes": [
      {
        "code": "18724-100"
      },
      {
        "code": "18724-5"
      }
    ]
  },
  {
    "resultDate": "14.03.2018 13:11:48",
    "codes": [
      {
        "code": "18724-99"
      }
    ]
  }
]

Maybe with a reduce function that groups the elements similar as described in this blog post. https://www.datchley.name/getting-functional-with-javascript-part-2/

Answer 1

The following expression can be used for this:

{
  "Export": Export{resultDate: code[]} ~> $each(function($v, $k) {
    {
      "resultDate": $k,
      "codes": $v.{"code": $}
    }
  })
}

The first part Export{resultDate: code[]} groups the data by resultDate then the $each function iterates over the name/value pairs to produce the output. Expressions like this will probably be easier once the $distinct function is added to the language (https://github.com/jsonata-js/jsonata/issues/117)