Array from variable is sent like a string in Postman

Question

I collected data from the response and pushed it into array in 'Tests'. console.log shows that I received array:

Then I saved it into environment variable to use in the next call. But value in the request was a string, so only the first value was running.

How can I set normal array?

Response from I collected data:

{
  "sent": 0,
  "remaining": 1000000,
  "gifts": [
    {
        "id": 43468,
        "amount": 50000,
        "can_gift_back": true
    },
    {
        "id": 43469,
        "amount": 50000,
        "can_gift_back": true
    }
  ]
}

My code in the "Tests" tab:

let jsonData = pm.response.json();
let gifts = jsonData.gifts;

//calculate array length
function objectLength(obj) {
    var result = 0;
        for(var prop in obj) {
            if (obj.hasOwnProperty(prop)) {
            result++;
            }    
        }
    return result;
}
let arrayLength = objectLength(gifts);

//push response data to the array
var giftsArray = [];
for (var i = 0; i < arrayLength; i++) {
        var giftsIDs = gifts[i].id;
        giftsArray.push(giftsIDs);
    }
pm.environment.set("giftsToCollect", giftsArray);

UPD:

1. After using code from the answer in different ways I received such issue.

Point 1 from the picture describes the way of behavior when stringify is used

Point 2 describes behavior when stringify is not used 2. Example of request JSON with manually inputed ids

Answer 1

You could capture all the id values in an array using Lodash, which is an external module that you can use in the Postman application.

Saving the array as a variable after this, is the same as you have done so already but I've added JSON.stringify() around the array value or it will save this as a string.

let giftsArray = []

_.each(pm.response.json().gifts, (item) => {
    giftsArray.push(item.id)
})

pm.environment.set('giftsToCollect', JSON.stringify(giftsArray))

You should then be able to reference the environment variable like this:

gift_ids: {{giftsToCollect}}

I've mocked out the request data locally, just to show you this capturing the values from the data.