Chaining request data in Postman

Introduction

Chaining request data helps you use information from one API response in the next request. This makes testing real and connected, like a conversation between apps.

When you need to use a user ID from a login response in a later request.

When you want to test a sequence of API calls that depend on each other.

When you want to automate tests that require dynamic data from previous responses.

When you want to verify workflows that involve multiple steps with shared data.

Syntax

Postman

// Extract data from response and save to variable
let jsonData = pm.response.json();
pm.environment.set("variable_name", jsonData.key);

// Use saved variable in next request URL or body
GET https://api.example.com/users/{{variable_name}}

Use pm.response.json() to parse JSON response.

Use pm.environment.set() or pm.collectionVariables.set() to save data for next requests.

Examples

This saves the user ID from the login response to an environment variable called userId.

Postman

// Save user ID from login response
let jsonData = pm.response.json();
pm.environment.set("userId", jsonData.user.id);

This uses the saved userId in the URL of the next request.

Postman

// Use saved userId in next request URL
GET https://api.example.com/users/{{userId}}

Saves an authentication token for use in headers of future requests.

Postman

// Save token from login response
let jsonData = pm.response.json();
pm.environment.set("authToken", jsonData.token);

This adds the saved token to the Authorization header for secure requests.

Postman

// Use token in Authorization header
Authorization: Bearer {{authToken}}

Sample Program

This example shows two requests chained together. The first saves the user ID from login. The second uses that ID to get user details and checks it matches.

Postman

// First request: Login and save user ID
pm.test("Login successful", function () {
    let jsonData = pm.response.json();
    pm.environment.set("userId", jsonData.user.id);
    pm.expect(jsonData.user).to.have.property('id');
});

// Second request: Get user details using saved userId
// URL: https://api.example.com/users/{{userId}}
pm.test("User details fetched", function () {
    let jsonData = pm.response.json();
    pm.expect(jsonData).to.have.property('id', pm.environment.get("userId"));
});

Important Notes

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

Use environment or collection variables to share data between requests safely.

Chaining helps test real user flows where data depends on previous steps.

Summary

Chaining request data lets you pass info from one API call to the next.

Use pm.response.json() to get data and pm.environment.set() to save it.

This makes your tests more realistic and connected.

Practice

1. What is the main purpose of chaining request data in Postman?

easy

A. To pass data from one API request to another for connected testing

B. To run multiple requests at the same time

C. To change the request method automatically

D. To generate random data for each request

Solution

1. Step 1: Understand chaining request data

   Chaining request data means using data from one API response in the next request to keep tests connected.

2. Step 2: Identify the purpose

   This helps simulate real user flows where one action depends on the previous one.

3. Final Answer:

   To pass data from one API request to another for connected testing -> Option A

4. Quick Check:

   Chaining = passing data between requests [OK]

Hint: Chaining means passing data forward between requests [OK]

Common Mistakes:

• Thinking chaining runs requests simultaneously
• Confusing chaining with changing HTTP methods
• Assuming chaining generates random data

2. Which Postman script correctly saves a value from a JSON response to an environment variable named userId?

easy

A. pm.response.set('userId', pm.environment.json().id);

B. pm.environment.get('userId', pm.response.json().id);

C. pm.response.get('userId', pm.environment.json().id);

D. pm.environment.set('userId', pm.response.json().id);

Solution

1. Step 1: Identify correct method to save variable

   Use pm.environment.set(key, value) to save data to environment variables.

2. Step 2: Extract value from response JSON

   Use pm.response.json() to parse JSON and get the id field.

3. Final Answer:

   pm.environment.set('userId', pm.response.json().id); -> Option D

4. Quick Check:

   Set environment variable = pm.environment.set [OK]

Hint: Use pm.environment.set to save data from pm.response.json() [OK]

Common Mistakes:

• Using pm.environment.get to set a variable
• Confusing pm.response and pm.environment methods
• Trying to get data from environment instead of response

3. Given this Postman test script after a request:

const jsonData = pm.response.json();
pm.environment.set('token', jsonData.auth.token);

What will be the value of the environment variable token if the response JSON is {"auth": {"token": "abc123"}}?

medium

A. null

B. undefined

C. "abc123"

D. Error: token not found

Solution

1. Step 1: Parse the response JSON

   The response JSON has an object with auth containing token with value "abc123".

2. Step 2: Set environment variable

   The script sets token variable to jsonData.auth.token, which is "abc123".

3. Final Answer:

   "abc123" -> Option C

4. Quick Check:

   token value = "abc123" [OK]

Hint: Check JSON path matches response structure exactly [OK]

Common Mistakes:

• Assuming token is undefined if nested
• Forgetting to parse JSON before accessing
• Expecting error when token exists

4. You wrote this script to chain data:

const data = pm.response.json();
pm.environment.set('userId', data.user.id);

But the environment variable userId is always empty after the request. What is the likely problem?

medium

A. The script must run before the request

B. The response JSON does not have a user object

C. You must use pm.variables.set instead

D. pm.environment.set cannot save variables

Solution

1. Step 1: Check JSON structure

   If data.user is undefined, accessing data.user.id returns undefined, so variable is empty.

2. Step 2: Confirm environment.set works correctly

   pm.environment.set works if given a valid value, so problem is likely missing user in response.

3. Final Answer:

   The response JSON does not have a user object -> Option B

4. Quick Check:

   Missing JSON key = empty variable [OK]

Hint: Verify JSON keys exist before accessing nested values [OK]

Common Mistakes:

• Assuming pm.environment.set is broken
• Using wrong method like pm.variables.set
• Running script before response is received

5. You want to chain two requests where the first returns a list of users:

{"users": [{"id": 1}, {"id": 2}]}

You want to save the id of the first user to an environment variable firstUserId and use it in the second request URL as /users/{{firstUserId}}. Which script correctly does this in the first request's Tests tab?

hard

A. const jsonData = pm.response.json();
pm.environment.set('firstUserId', jsonData.users[0].id);

B. const jsonData = pm.response.json();
pm.environment.set('firstUserId', jsonData.users.id[0]);

C. const jsonData = pm.response.json();
pm.environment.set('firstUserId', jsonData.users[1].id);

D. const jsonData = pm.response.json();
pm.environment.set('firstUserId', jsonData.user[0].id);

Solution

1. Step 1: Parse response JSON correctly

   The response has a users array with objects containing id. The first user is at index 0.

2. Step 2: Save first user's id properly

   Access jsonData.users[0].id and save it with pm.environment.set.

3. Final Answer:

   const jsonData = pm.response.json(); pm.environment.set('firstUserId', jsonData.users[0].id); -> Option A

4. Quick Check:

   Array index 0 for first user id [OK]

Hint: Use array index [0] to get first item in JSON array [OK]

Common Mistakes:

• Using wrong array index or property name
• Accessing id as users.id[0] instead of users[0].id
• Using singular 'user' instead of 'users'