how to add an element in a json body from pre-request or datafile?

Question

Trying to figure out how can I insert a new row under net. Basically I need to figure out how many are already in there so I dont overlap it , and append a new one.

Original:

{
  "jsonrpc": "2.0",
  "method": "update",
  "params": {
    "vid": 10,
    "_update": {
      "data": {
        "lan": {
          "net": [
            {
              "id": 1,
              "name": "FIRST"
            },
            {
              "id": 15,
              "name": "SECOND"
            }
          ]
        }
      }
    }
  },
  "id": 1
}

Wanted to add:

{
  "id": 8,
  "name": "THIRD"
}

So FINAL would be new

{
  "jsonrpc": "2.0",
  "method": "update",
  "params": {
    "vid": 10,
    "_update": {
      "data": {
        "lan": {
          "net": [
            {
              "id": 1,
              "name": "FIRST"
            },
            {
              "id": 15,
              "name": "SECOND"
            },
            {
              "id": 8,
              "name": "THIRD"
            }
          ]
        }
      }
    }
  },
  "id": 1
}

To clarify: I will make a POST that retrieves a json data - which is not fixed, it may have more elements or less every time I run the POST.

I'd like to add something to this json and use it to POST it into another request.

I figure I could store the reply in a env.variable using TEST, that part works, then use this env.variable as a body in another POST this works as well

now I just need to figure out how to add something into the JSON I collected in my first POST, that is the original question :)

Answer 1

how is the third entry stored in the datafile?

If its stored as a string, i would suggest the pragmatic way: Just add the variable into the JSON Body(but don't forget the comma).

{
    "jsonrpc": "2.0",
    "method": "update",
    "params": {
        "vid": 10,
        "_update": {
            "data": {
                "lan": {
                    "net": [
                        {
                            "id": 1,
                            "name": "FIRST"
                        },
                        {
                            "id": 15,
                            "name": "SECOND"
                        },
                        {{data_value}}
                    ]
                }
            }
        }
    },
    "id": 1
}

if the data is stored separately e.g. as id and name, just add this to your pre-request-script:

var myNewObject = { id : data.id, name:data.name};
pm.globals.set("myNewObject", JSON.stringify(myNewObject));

This snippet will add a new Object with id and name, and set it up with the data id and name from your datafile. It will be stored as a global variable myNewObject, which can be used in your body (don't forget the comma ;-) ):

{
    "jsonrpc": "2.0",
    "method": "update",
    "params": {
        "vid": 10,
        "_update": {
            "data": {
                "lan": {
                    "net": [
                        {
                            "id": 1,
                            "name": "FIRST"
                        },
                        {
                            "id": 15,
                            "name": "SECOND"
                        },
                        {{myNewObject}}
                    ]
                }
            }
        }
    },
    "id": 1
}

An other idea can be to store the whole "net" array in a variable. You can append the new object to this array. But in this Case the whole "net" array must be known (e.g. From a global variable).

JsonBody

{
    "jsonrpc": "2.0",
    "method": "update",
    "params": {
        "vid": 10,
        "_update": {
            "data": {
                "lan": {
                    "net": {{netArray}}
    },
    "id": 1
}

pre-request script

var myNewObject = { id : data.id, name:data.name};
var netArray = JSON.parse(pm.globals.get("netArray"));
netArray.push(myNewObject); //<-- Adds new object to the array
pm.globals.set("netArray", JSON.stringify(netArray));