jolt transformation to remove key if value is not present

Question

I have an input json in the form of key, value pair. I don't want to include the key in the output if value for that key is missing. As in this input teacherid is missing, so it shouldn't be included in the ouput.

input :

{
  "alldetails": {
    "classid": 1,
    "schoolid": 3
  }
}

jolt spec :

[
  {
    "operation": "shift",
    "spec": {
      "alldetails": {
        "#Id_class": "data[0].source",
        "classid": "data[0].value",
        "#Id_teacher": "data[1].source",
        "teacherid": "data[1].value",
        "#Id_school": "data[2].source",
        "schoolid": "data[2].value"
      }
    }
  }
]

current output :

{
  "data": [
    {
      "source": "Id_class",
      "value": 1
    },
    {
      "source": "Id_teacher"
    },
    {
      "source": "Id_school",
      "value": 3
    }
  ]
}

desired output :

{
  "data": [
    {
      "source": "Id_class",
      "value": 1
    },
    {
      "source": "Id_school",
      "value": 3
    }
  ]
}

Any help would be appreciated. Thanks

Answer 1

https://jolt-demo.appspot.com/#inception runs on v0.1.1 which is old and don't support all features so created new on v0.1.6 https://vishavjeet6.github.io/jolt-transformer/

This worked for me

[
  {
    "operation": "shift",
    "spec": {
      "alldetails": {
        "classid": {
          "#Id_class": "data[0].source",
          "@(1,classid)": "data[0].value"
        },
        "teacherid": {
          "#Id_teacher": "data[1].source",
          "@(1,teacherid)": "data[1].value"
        },
        "schoolid": {
          "#Id_school": "data[2].source",
          "@(1,schoolid)": "data[2].value"
        }
      }
    }
  },
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": "=recursivelySquashNulls"
    }
  }
]