JDT transform to modify N-th array element

Question

I am trying to apply a JDT transform to a JSON document in order to modify a property in a N-th array element. Is that possible without having to replace the entire element or even the entire array?

{
  "array": [
    {
      name: "A",
      value: 0
    },
    {
      name: "B",
      value: 3.14
    }
  ]
}

Is there a transform that gets me to the following? I want to alter the 2nd array element and only its "value" property. I don't want to search for it by "name" but rather access by index.

{
  "array": [
    {
      name: "A",
      value: 0
    },
    {
      name: "B",
      value: 12345678
    }
  ]
}

Answer 1

The challenge

It is easy to do your transform with some libraries in JSON. If your object is called foo, you mainly want to something like foo.array[1].value = "12345678" without any kind of looping.

The JDT way

I found How to use SlowCheetah to transform an array elements in Json config file? which asks

For example, if my base config file has this setting:

{
  "Settings" :  [1, 2, 3] 
}

and I want to transfer it to:

{
  "Settings" :  [4, 5, 6] 
}

The solution by Collin K was

{
  "@jdt.replace": {
    "@jdt.path": "$.Settings",
    "@jdt.value": [4,5,6]
  }
}

This seems like you need to actually replace the whole array.

Digging further let me to an open issue of JDT which seems to confirm this assumption.

Disclaimer

I have not used JDT myself, but I have been struggling with nested JSONs of various kinds e.g. with Elasticsearch.

Further references

• https://github.com/microsoft/json-document-transforms/wiki/Replace-Transformation
• Using jq to update objects within a JSON document if the value corresponding to a given key starts with a specified string - the JQ way I would use