Jolt Spec to create a counter based on the column

Question

I am facing a problem, transforming a JSON . Requirement is create a counter based on the column.

Input :

[
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "111"
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "111"
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "222"
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "222"
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "222"
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "333"
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "333"
  }
]

In the above JSON, we have 3 different stop IDs. I need to create a stopsequence based on the stopId. If the stopIds are same, i need to retain the counter, if the stopIds are different, counter needs to be incremented.

Output Expected :

[
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "111",
    "stopSequence": 1
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "111",
    "stopSequence": 1
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "222",
    "stopSequence": 2
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "222",
    "stopSequence": 2
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "222",
    "stopSequence": 2
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "333",
    "stopSequence": 3
  },
  {
    "shipment_id": "a60e3760-2f7f-41f3-ac8d-2edd424bcfe4",
    "stopId": "333",
    "stopSequence": 3
  }
]

In the above JSON, we have 3 different stop IDs. I need to create a stopsequence based on the stopId. If the stopIds are same, i need to retain the counter, if the stopIds are different, counter needs to be incremented.

Answer 1

You can manage to solve it through principle of grouping them by "stopid" values such as

[
  { // group by the "stopId" values
    "operation": "shift",
    "spec": {
      "*": {
        "*": "@1,stopId.&"
      }
    }
  },
  { // get rid of the objects labels
    "operation": "shift",
    "spec": {
      "*": ""
    }
  },
  { // generate ordinals 0,1,2 ... for the objects
    "operation": "shift",
    "spec": {
      "*": "&"
    }
  },
  { // generate the "ss" attribute as constructor for "stopSequence" with values 0,1,2 ...
    "operation": "shift",
    "spec": {
      "*": {
        "@": "&1",
        "$": "&1.ss"
      }
    }
  },
  { // increment the "ss" values by 1
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": {
        "ss": "=intSum(@(1,&),1)"
      }
    }
  },
  { // generate the "stopSequence" arrays
    "operation": "shift",
    "spec": {
      "*": {
        "stopId": {
          "@1": "&2",
          "*": {
            "@2,ss": "&3.stopSequence"
          }
        }
      }
    }
  },
  { // get rid of the "ss" attributes
    "operation": "remove",
    "spec": {
      "*": {
        "ss": ""
      }
    }
  },
  { // flatten all of the arrays
    "operation": "shift",
    "spec": {
      "*": {
        "*": {
          "*": "&2.&.&1"
        }
      }
    }
  },
  { // get rid of the objects labels
    "operation": "shift",
    "spec": {
      "*": {
        "*": ""
      }
    }
  }
]

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