How to get elements from array with Jolt Transform and make new attributes with their values in NiFi

Question

I have a JSON:

{
  "FILE": "23, 21, 24, 25"
}

I need it to look like this:

[
  {
    "FILE": {
      "First": "23",
      "Second": "21",
      "Third": "24",
      "Fourth": "25"
    }
  }
]

I made an array first with jolt transformation:

[
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "FILE": "=split(',',@(1,FILE))"
    }
  }
]

So now I have:

{
  "FILE": [
    "23",
    "21",
    "24",
    "25"
  ]
}

How can I get elements from this array and make new attributes with them? Is there any way to get them by index maybe?

Answer 1

There's no converter function to determine literal ordinals, but suffixes (st,nd,rd,th) along with incremented numerical indexes might be presented through the following transformation :

[
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": "=split(', ',@(1,&))"
    }
  },
  {//generate values vs. keys
    "operation": "shift",
    "spec": {
      "*": {
        "*": {
          "@": "&2.v_&",
          "$": "&2.k_&"
        }
      }
    }
  },
  {//increment keys by one
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": {
        "k_*": "=intSum(1,@(1,&))"
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": {
        "k_*|v_*": "&1.&(0,1)"
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": {
        "*": {
          "0": "&2.@(1,[1])"
        }
      }
    }
  },
,
  { // add ordinal suffixes
    "operation": "shift",
    "spec": {
      "*": {
        "1|*1": {
          "@": "&2.&st"
        },
        "2|*2": {
          "@": "&2.&nd"
        },
        "3|*3": {
          "@": "&2.&rd"
        },
        "*|11|12|13": {
          "@": "&2.&th"
        }
      }
    }
  }
]

which will result for a JSON input of :

{
  "FILE" : {
    "1st" : "23",
    "2nd" : "21",
    "3rd" : "24",
    "4th" : "25",
    "5th" : "29",
    "6th" : "32"
  }
}

for the input

{
  "FILE": "23, 21, 24, 25, 29, 32"
}