Copy a value from field to another field using Jolt while preserving the rest of the document-CodePudding

I'm trying to use a JOLT spec to copy the value from a JSON object to another field in the same object and keep the original document (with the new field) .

I'm trying using the shift operator, but I just can't figure out how to preserve the document.

Here's an example of the Object I'm trying to transform:

{
  "contact": {
    "name": "Foo",
    "id": "123456",
    "phone": "231-123"
  },
  "event": {
    "name": "create",
    "type": "test"
  }
}

And the output should be something like this:

{
  "contact": {
    "name": "Foo",
    "id": "123456",
    "userId": "123456",
    "phone": "231-123"
  },
  "event": {
    "name": "create",
    "type": "test"
  }
}

In this case I want to copy the value from id to a new field named "userId"

The specs I've tried are:

[
  {
    "operation": "shift",
    "spec": {
      "*": "&",
      "contact": {
        "userId": "contact.id"
      }
    }
  }
]

But that just deletes everything but the event node.

CodePudding user response：

Using a modify transform would suit best for your case such as

[
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "contact": {
        "userId": "@(1,id)" // goes 1 level up the tree and grabs the value of the "id" attribute
      }
    }
  }
]

the demo on the site

Btw, using a shift transformation is also possible such as

[
  {
    "operation": "shift",
    "spec": {
      "contact": {
        "*": "&1.&",
        "@(0,id)": "&1.userId" // in this case, we have "0" instead of "1", since no need to go up the tree as identifier of value @(0,id) is on the left hand side, exactly stays at the same level with the tag "id"
      },
      "*": "&"
    }
  }
]

but obviously, the first one is simpler.