@MDTechie - Here is a provided solution for the question you asked. I usually like to Jolt Transforms step by step. Please see the Jolt Spec below along with explanations for each step.

[
  {
    "operation": "shift",
    "spec": {
      "id": "id",
      "categories": {
        "*": {
          "@": "categories[]",
          "subcategories": {
            "*": {
              "@": "categories[]"
            }
          }
        }
      }
    }
  },
  {
    "operation": "remove",
    "spec": {
      "categories": {
        "*": {
          "subcategories": ""
        }
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "categories": {
        "*": {
          "code": "categories[&1].categoryCode",
          "name": "categories[&1].categoryName",
          "@(2,id)": "categories[&1].individualId"
        }
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "categories": {
        "*": ""
      }
    }
  }
]

The first operation

1. Copies the id field from the original input to the top level of the output.
2. Iterates over the categories array and:
   • Copies each category object to a new array called categories[].
   • If a category contains a subcategories array, each subcategory object is also copied into the same categories[] array, effectively flattening the nested structure.

The second operation

1. Searches within each category object in the categories[] array.
2. Removes the subcategories field if it exists.

The third operation

1. Iterates over the categories[] array, processing each category object.
2. Renames the code field to categoryCode and the name field to categoryName for consistency with the new output schema.
3. Adds a new field called individualId inside each category object, using the id value from two levels up (the root of the original input).

The fourth operation:

1. Takes each object from the categories[] array and moves it to the root level.
2. As a result, the categories array wrapper is removed, leaving a flat array of individual objects.

I suggest piecing it out in a JOLT tester to understand it a little better. Hope this helps! 🙂 

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