Re-parent a JSON object using Jolt

Question

I'd like to move a JSON object down one level using Jolt. Here's my input data :

{
    "rating": {
        "primary": {
            "value": 3,
            "max": 5
        },
        "quality": {
            "value": 3,
            "max": 7
        }
    }
}

I'm using the following spec file :

[
  {
    "operation": "shift",
    "spec": {
      "$": "NEWPARENT"
    }
  }
]

I'm currently producing this output :

{
  "NEWPARENT" : "root"
}

However, my goal is to produce :

{
  "NEWPARENT": {
    "rating": {
      "primary": {
        "value": 3,
        "max": 5
      },
      "quality": {
        "value": 3,
        "max": 7
      }
    }
  }
}

Can anyone help me create the proper spec file?

Answer 1

Spec

[
  {
    "operation": "shift",
    "spec": {
      "@": "NEWPARENT"
    }
  }
]

FYI, the "root" you are seeing is an artifact of the way that Jolt deals with the fact that the top level JSON input can be either a List or a Map, and that you want to be able to Transform a List into a Map (and vice versa).

So, jolt "wraps" the input so that it is "always" transforming a Map that has a single key "root", with a value that is the input.