Jolt Transform JSON Spec for Array Input

Question

I am trying to do JOLT shift operation with below spec which is not working. Not sure what mistake I have done. Need help in this case. Output JSON is coming as an object instead of Array and shift also not working as expected.

    Input : [
      {
        "Header": {
          "Number": 1,
          "Id": "JO"
        },
        "Name": "John"
      },
      {
        "Header": {
          "Number": 2,
          "Id": "JS"
        },
        "Name": "Justin"
      }
    ]

    Spec : [
      {
        "operation": "shift",
        "spec": {
          "*": {
            "Header": "Header",
            "Name": "Header.Name"
          }
        }
      }
    ]

    Expected Output : [
      {
        "Header": {
          "Number": 1,
          "Id": "JO",
          "Name": "John"
        }    
      },
      {
        "Header": {
          "Number": 2,
          "Id": "JS",
          "Name": "Justin"
        }    
      }
    ]

    Actual Output : {
      "Header" : [ {
        "Number" : 1,
        "Id" : "JO",
        "Name" : "John"
      }, {
        "Number" : 2,
        "Id" : "JS"
      } ]
    }

kasptom · Accepted Answer · 2020-08-28 11:33:20Z

2

You have to also specify that the "Header" object is inside the array.

Moreover, the index of the array where you place the "Header" object for each of the element of the array.

That's what the spec below does (using the [&1] - apmersand wildcard combined with array):

[
  {
    "operation": "shift",
    "spec": {
      "*": {
        "Header": "[&1].Header",
        "Name": "[&1].Header.Name"
      }
    }
  }
]

Sources:

Shiftr.java javadocs:
- The arrays
- The ampersand wildcard
Other answer: "How do I transform an array using Jolt?"
Demo application linked in the jolt repo to test the spec

edited Aug 28, 2020 at 11:33

answered Aug 27, 2020 at 13:46

kasptom

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3 Comments

Balaji211 Over a year ago

Thanks, @kasptom. It's working. You helped me on 3 issues till now related to JOLT.

ΦXocę 웃 Пepeúpa ツ Over a year ago

any good source to read the documentation of jolt? this is very obscure until now...#

kasptom Over a year ago

@ΦXocę웃Пepeúpaツ I've edited the answer and added the best sources I know of.

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