Extracting data from responses in Postman

Introduction

We extract data from responses to use it in later tests or requests. This helps us check if the system works correctly step-by-step.

When you want to save a user ID from a login response to use in another request.

When you need to get a token from a response to authorize future requests.

When you want to check if a specific value appears in the response data.

When you want to pass data dynamically between multiple API calls in a test collection.

Syntax

Postman

pm.test("Extract value from response", function () {
    var jsonData = pm.response.json();
    pm.environment.set("keyName", jsonData.data.id);
});

Use pm.response.json() to parse the response body as JSON.

Use pm.environment.set("key", value) to save data for later use.

Examples

This saves the token from the response into an environment variable called userToken.

Postman

pm.test("Save user token", function () {
    var jsonData = pm.response.json();
    pm.environment.set("userToken", jsonData.token);
});

This saves the order.id into a collection variable named orderId.

Postman

pm.test("Extract order ID", function () {
    var jsonData = pm.response.json();
    pm.collectionVariables.set("orderId", jsonData.order.id);
});

This checks if the response status code is 200 (OK).

Postman

pm.test("Check response status", function () {
    pm.response.to.have.status(200);
});

Sample Program

This test extracts the user.id from the JSON response and saves it as an environment variable userID. It also checks that the ID is a number.

Postman

pm.test("Extract user ID from response", function () {
    var jsonData = pm.response.json();
    pm.environment.set("userID", jsonData.user.id);
    pm.expect(jsonData.user.id).to.be.a('number');
});

Important Notes

Always check the response format before extracting data to avoid errors.

Use environment or collection variables to share data between requests.

Use descriptive variable names to keep your tests clear.

Summary

Extracting data helps connect multiple API requests in tests.

Use pm.response.json() to read JSON responses.

Save data with pm.environment.set() or pm.collectionVariables.set().