Chaining request data in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Postman test script chaining example?

Consider two requests in Postman: Request A saves a token in environment variable authToken. Request B uses this token in its header. What will be the value of the Authorization header in Request B if Request A's test script is:

pm.environment.set('authToken', 'abc123');

and Request B's header is set as Bearer {{authToken}}?

A abc123

B Bearer {{authToken}}

C Bearer abc123

D Authorization header will be empty

💡 Hint

Remember how Postman replaces variables in double curly braces with their stored values.

Postman replaces {{authToken}} with the value stored in the environment variable authToken. Since Request A sets it to 'abc123', Request B's header becomes 'Bearer abc123'.

❓ assertion

intermediate

Which assertion correctly verifies the chained response value in Postman?

Request A returns JSON: {"userId": 42}. Request B needs to assert that the userId in its response matches the one saved from Request A. Which Postman test script correctly asserts this?

A pm.test('UserId matches', () => { pm.expect(pm.response.json().userId).to.eql(pm.variables.get('userId')); });

B pm.test('UserId matches', () => { pm.expect(pm.response.json().userId).to.eql('userId'); });

C pm.test('UserId matches', () => { pm.expect(pm.response.userId).to.eql(pm.environment.userId); });

D pm.test('UserId matches', () => { pm.expect(pm.response.json().userId).to.eql(pm.environment.get('userId')); });

💡 Hint

Check how to get environment variables and parse JSON response in Postman.

Option D correctly gets the JSON response, extracts userId, and compares it to the environment variable userId using pm.environment.get(). Other options either use wrong methods or incorrect values.

🔧 Debug

advanced

Why does this chained request fail to use the saved variable?

Request A test script saves a value with:

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

Request B uses {{sessionId}} in the URL. But Request B sends the URL with {{sessionId}} literally, not replaced. What is the most likely cause?

A Request B runs before Request A finishes, so variable is not set yet.

B The variable name is misspelled in Request B's URL.

C Environment variables are disabled in Postman settings.

D Request A's test script has a syntax error preventing variable set.

💡 Hint

Think about the order of request execution and when variables become available.

If Request B runs before Request A completes and sets the variable, the variable is not yet defined, so Postman leaves the placeholder {{sessionId}} as is. This usually happens if requests are run in parallel or manually out of order.

❓ framework

advanced

Which Postman feature best supports chaining multiple requests with dynamic data?

You want to run a sequence of requests where each request uses data from the previous response. Which Postman feature helps automate this chaining?

A Running requests in separate tabs simultaneously

B Collection Runner with environment variables and pre-request scripts

C Using Postman monitors without variables

D Manual execution of requests one by one

💡 Hint

Think about automating sequences and passing data between requests.

Collection Runner allows running multiple requests in order, using environment variables and scripts to pass data dynamically between requests. Manual execution or running requests simultaneously does not automate chaining effectively.

🧠 Conceptual

expert

What is the best practice to securely chain sensitive data between Postman requests?

You need to chain an authentication token from Request A to Request B, but want to avoid exposing it in logs or sharing it accidentally. What is the best practice?

A Store the token in a Postman environment variable with <code>secret</code> flag enabled and clear it after use

B Save the token in a global variable for easy access across collections

C Hardcode the token in Request B's headers to avoid variable exposure

D Print the token in console logs for debugging and remove later

💡 Hint

Consider how Postman handles sensitive data and variable scopes.

Marking environment variables as secret hides their values in the UI and logs. Clearing them after use reduces exposure risk. Global variables are shared widely and less secure. Hardcoding tokens is insecure. Printing tokens in logs risks exposure.

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'