How to append an array nested inside JSON object using JSONata

Question

I'm trying to use JSONata to append an extra object within the "options" array in the following JSON:

{
  "description": "[IGNORE] Field used for testing",
  "displayOrder": 2,
  "fieldType": "select",
  "formField": true,
  "groupName": "excell_data",
  "label": "Dev Test Field [IGNORE]",
  "name": "dev_test_field",
  "options": [
    {
      "description": "Choice number one",
      "displayOrder": 1,
      "hidden": false,
      "label": "Option 1",
      "value": "1"
    },
    {
      "description": "Choice number two",
      "displayOrder": 2,
      "hidden": false,
      "label": "Option 2",
      "value": "2"
    },
    {
      "description": "Choice option three",
      "displayOrder": 3,
      "hidden": false,
      "label": "Option 3",
      "value": "3"
    }
  ],
  "type": "enumeration"
}

So that it becomes:

{
  "description": "[IGNORE] Field used for testing",
  "displayOrder": 2,
  "fieldType": "select",
  "formField": true,
  "groupName": "excell_data",
  "label": "Dev Test Field [IGNORE]",
  "name": "dev_test_field",
  "options": [
    {
      "description": "Choice number one",
      "displayOrder": 1,
      "hidden": false,
      "label": "Option 1",
      "value": "1"
    },
    {
      "description": "Choice number two",
      "displayOrder": 2,
      "hidden": false,
      "label": "Option 2",
      "value": "2"
    },
    {
      "description": "Choice option three",
      "displayOrder": 3,
      "hidden": false,
      "label": "Option 3",
      "value": "3"
    },
    {
      "description": "Choice number four",
      "displayOrder": 4,
      "hidden": false,
      "label": "Option 4",
      "value": 4
    }
  ],
  "type": "enumeration"
}

However when I try to use the append function, I am struggling to return the parent JSON along with the appended object nested within.

JSONata fiddler link here: https://try.jsonata.org/iv7zhPZcr

Could anyone shed light on where I'm going wrong?

Many thanks in advance. Jonathan

Answer 1

Use the transform operator to modify the options object in the parent object:

$ ~> | $ | {
    "options": [options, {
        "description": "Choice number four",
        "displayOrder": 4,
        "hidden": false,
        "label": "Option 4",
        "value": 4
    }]
} | 

See: https://try.jsonata.org/9RLURkd9l

https://docs.jsonata.org/other-operators#-------transform