Saving a string from POST as a variable

Hello. Trying to figure out how to save a string from a post and save it as a variable to use in my next test.

The JSON returns data like so

"{\"a_gains\": [1.8499999999999996, 20.15, 19.7, 13.275, 9.4, 12.5, 16.59], \"b_gains\": [1.8499999999999996, 20.15, 19.7, 13.275, 9.4, 12.5, 32.59], \"session_id\": "

In the past I would look in the json object and find the object and save it, but I’m not sure how to do so with a string. EG If i try something like this

const jsonData = pm.response.json();

pm.test(‘Session_id is’ + jsonData.session_id, function() {


Then session_id just comes back as undefined. Is it because It’s not an object in the JSON?
I know it can see the string. If i do a simple test like so

pm.test("Body matches string", function () {

It tells me the body does match the string.

Hello @cdolan90, Welcome to the community :tada:

The shared JSON data looks like a string, so try converting to JSON object, and that’s probably the reason you are getting session_id as undefined.

var RandData = JSON.parse("{\"a_gains\": [1.8499999999999996, 20.15, 19.7, 13.275, 9.4, 12.5, 16.59], \"b_gains\": [1.8499999999999996, 20.15, 19.7, 13.275, 9.4, 12.5, 32.59], \"session_id\": 1795, \"sound_file\": \"gs://sound-files-test/comparison/8k/comparison_Listen_to_the.wav\", \"step_count\": 1}");

var data = pm.response.json()

/* you can set the collection/environment/global variables (below is collectionVariables)*/
pm.collectionVariables.set("session_id", RandData.session_id)

/*To check whether you have session_id as key or not*/
pm.test("session_id is available in JSON data", function () {

And if you are not converting to JSON object and directly checking for session_id.

pm.test("Body matches string", function () {

All the best :+1: :grinning:

Hi Sahuvikramp.

This worked thank you. The issue is that i’m having is session_id will always return a different number, so in my example it was 1795 but it changes everytime. Is there a way to parse the JSON so it returns that value instead of a hard coded one?

Edit: I’ve found the solution but thank you for pointing me in the right direction.

let response = pm.response.json();

var RandData = JSON.parse(response);

postman.setEnvironmentVariable("session_id", RandData.session_id);
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