How to use shift and modify-overwrite-beta in jolt

I want to know how to use shift and modify-overwrite-beta for the below input. Please explain how it works with your answer.

my input

[
  {
    "data": {
      "firstName": "Leanne",
      "lastName": "Graham",
      "id": 111
    }
  },
  {
    "data": {
      "firstName": "Ervin",
      "lastName": "Howell",
      "id": 222
    }
  }
]

I want this output

{
  "111": {
    "fullName": "Leanne Graham"
  },
  "222": {
    "fullName": "Ervin Howell"
  }
}

>Solution :

You can solve that in different ways.

1. This spec is more understandable:

1. Order your list with the id value as a key in the shift operation: @(1,id)
2. Concat firstName and lastName in the modify-overwrite-beta operation: =concat(@(1,firstName),' ',@(1,lastName))
3. Remove unused keys in the remove operation: id, firstName, lastName

[
  {
    "operation": "shift",
    "spec": {
      "*": { // index of the array: 1, 2
        "*": { // data object
          "*": "@(1,id).&" // value of id in the current object: 111, 222
        }
      }
    }
  },
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": { // ids: 111, 222
        "fullName": "=concat(@(1,firstName),' ',@(1,lastName))"
      }
    }
  },
  {
    "operation": "remove",
    "spec": {
      "*": { // ids: 111, 222
        "id": "",
        "firstName": "",
        "lastName": ""
      }
    }
  }
]

2. This spec is shorter:

1. Concat firstName and lastName in the modify-overwrite-beta operation: =concat(@(1,firstName),' ',@(1,lastName))
2. Get the value of id as a key and put fullname in it: key @(1,id).fullName, value @(0,fullName)

[
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": {
        "*": {
          "fullName": "=concat(@(1,firstName),' ',@(1,lastName))"
        }
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": {
        "*": {
          "@(0,fullName)": "@(1,id).fullName"
        }
      }
    }
  }
]