jolt transformation to concatenate two elements of a JSON array

Question

Hi I am novice to jolt transformation. I need help with following requirement.

input :

[
  {
    "firstName": "Fname1",
    "lastName": "Lname1",
    "state": "PA"
  },
  {
    "firstName": "Fname2",
    "lastName": "Lname2",
    "state": "VA"
  },
  {
    "firstName": "Fname3",
    "lastName": "Lname3",
    "state": "CA"
  }
]

expected output:

{
  "names": [
    "Fname1 Lname1",
    "Fname2 Lname2",
    "Fname3 Lname3"
  ],
  "states": [
    "PA",
    "VA",
    "CA"
  ]
}

Answer 1

You can use consecutive shift and modify transformation specs such as

[
  {
    // combine names under common array while converting states to a unique array
    "operation": "shift",
    "spec": {
      "*": {
        "*Name": "names[&1].&1", // convert all ...Names to array of objects
        "state": "&s" // convert label of the array to state"s" while tiling the components of it
      }
    }
  },
  {
    // concatenate respective (F/L)names values
    "operation": "modify-overwrite-beta",
    "spec": {
      "names": {
        "*": {
          "*": "=join(' ',@(1,&))"
        }
      }
    }
  },
  {
    // convert array of objects to basic array
    "operation": "shift",
    "spec": {
      "n*": {
        "*": {
          "*": "&2[&1]"
        }
      },
      "*": "&" // else case, eg. "states" array
    }
  },
  {
    "operation": "sort"
  }
]

the demo on the site http://jolt-demo.appspot.com/ is