[SOLVED] Replace empty string with null via JOLT SPEC

Replace empty string with null via JOLT SPEC

within a JSON I have several values which represent an empty string (they could be on highest level or one level below).

Input:

{
  "test": "value1",
  "test2": "",
  "test3": "value2",
  "test3_extra": {
    "test3_extra1": "",
    "test3_extra2": "random"
  }
}

Whenever an empty string occurs, I would like to replace it by null.

Desired Output:

{
  "test": "value1",
  "test2": null,
  "test3": "value2",
  "test3_extra": {
    "test3_extra1": null,
    "test3_extra2": "random"
  }
}

Can someone give me a hint on how to do this? Thanks in advance for your support.

Solution

You can use following shift transformation spec in which the "" values should be used on the left-hand-side like keys such as :

[
  {
    "operation": "shift",
    "spec": {
      "*": {//outermost attributes
        "": "&1",
        "*": {
          "@1": "&2"
        }
      },
      "*_extra": {//one-level nested attributes
        "*": {
          "": "&2.&1",
          "*": {
            "@1": "&3.&2"
          }
        }
      }
    }
  }
]

the demo on the site Jolt Transform Demo Using v0.1.1 is :