JOLT - Join arrays in nested array

Question

I am trying to achieve the following transformation. However, my solution adds undesired null values into the final array.

The transformation needs to shift names in child array for all root elements. I have created 3 cases to illustrate the problem.

Case 1

Input

{
  "root": [
    {
      "child": [
        {
          "name": "John"
        },
        {
          "name": "Frazer"
        }
      ]
    },
    {
      "child": [
        {
          "name": "Brandon"
        },
        {
          "name": "Josef"
        }
      ]
    }
  ]
}

Desired Output

{
  "NAMES": ["John,Frazer","Brandon,Josef"]
}

Case 2: One `child` is empty

Input

{
  "root": [
    {
      "child": []
    },
    {
      "child": [
        {
          "name": "Brandon"
        },
        {
          "name": "Josef"
        }
      ]
    }
  ]
}

Desired Output

{
   "NAMES": ["","Brandon,Josef"]
}

Case 3: All `child`s are empty

Input

{
  "root": [
    {
      "child": []
    },
    {
      "child": []
    }
  ]
}

Desired Output

{
   "NAMES": ["",""]
}

EDIT: root array will always have at least 1 element.

Current JOLT spec works fine except for cases where child is an empty array. It generates null values and I'm trying to specify an empty string instead (or any hardcoded string value such as "NO_NAMES")

[
  {
    "operation": "shift",
    "spec": {
      "root": {
        "*": {
          "child": {
            "*": {
              "name": "NAMES[&3]"
            }
          }
        }
      }
    }
  },
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "NAMES": {
        "*": "=trim"
      }
    }
  },
  {
    "operation": "cardinality",
    "spec": {
      "NAMES": "MANY"
    }
    },
  {
    "operation": "default",
    "spec": {
      "NAMES": []
    }
  },
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "NAMES": {
        "*": "=join(',',@0)"
      }
    }
  }
]

Hi @BarbarosÖzhan, thanks your help again. I've added my current spec. The default node is one of my attempts but does not help me achieve my goal. — David Segovia
– David Segovia, Commented Jul 5, 2021 at 11:26
That is my main problem. I need it to be { "NAMES" : [ "", "" ] } instead. Or { "NAMES" : [ "NO_NAMES", "NO_NAMES" ] }. Both solutions would be valid. NAMES should be the same length as root. — David Segovia
– David Segovia, Commented Jul 5, 2021 at 11:37

Barbaros Özhan · Accepted Answer · 2021-07-05 22:00:31Z

1

You can apply consecutive transformations modify-overwrite-beta and then shift in order to determine comma-seperated elements of the list(unless they have zero size,this case only double quotes will appear), and then concatenate them within a list such as

[
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "root": {
        "*": {
          "child": { "*": "@(0,name)" },
          "NAMES": "=join(',',@(1,child))"
        }
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "root": {
        "*": {
          "NAMES": "&"
        }
      }
    }
  }
]

answered Jul 5, 2021 at 22:00

Barbaros Özhan

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JOLT - Join arrays in nested array

Case 1

Input

Desired Output

Case 2: One `child` is empty

Input

Desired Output

Case 3: All `child`s are empty

Input

Desired Output

1 Answer 1

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Collectives™ on Stack Overflow

Case 1

Input

Desired Output

Case 2: One child is empty

Input

Desired Output

Case 3: All childs are empty

Input

Desired Output

1 Answer 1

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Case 2: One `child` is empty

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