Using extracted data in next request in Postman - Test Execution Trace

Test Overview

This test sends a first API request to get a user ID, extracts that ID from the response, and uses it in the next API request to fetch user details. It verifies that the user details response contains the correct user ID.

Test Code - Postman

Postman

pm.test("Extract user ID and use in next request", function () {
    pm.sendRequest({
        url: 'https://api.example.com/users',
        method: 'GET'
    }, function (err, res) {
        pm.expect(err).to.be.null;
        pm.expect(res).to.have.property('code', 200);
        const userId = res.json().data[0].id;
        pm.environment.set('userId', userId);

        pm.sendRequest({
            url: `https://api.example.com/users/${userId}`,
            method: 'GET'
        }, function (err2, res2) {
            pm.expect(err2).to.be.null;
            pm.expect(res2).to.have.property('code', 200);
            pm.expect(res2.json().id).to.eql(userId);
        });
    });
});

Execution Trace - 4 Steps

Step	Action	System State	Assertion	Result
1	Test starts and sends GET request to 'https://api.example.com/users' to get list of users	API server is reachable and returns a JSON list of users	Response status code is 200	PASS
2	Extract the first user's ID from the response JSON and save it to environment variable 'userId'	Environment variable 'userId' is set with extracted user ID	Extracted user ID is not null or undefined	PASS
3	Send GET request to 'https://api.example.com/users/{userId}' using extracted user ID	API server returns user details for the specified user ID	Response status code is 200	PASS
4	Verify that the returned user details JSON contains the same user ID as extracted	Response JSON contains user ID matching environment variable	User ID in response equals extracted user ID	PASS

Failure Scenario

Failing Condition: The first API request fails or returns no users, so user ID cannot be extracted

Execution Trace Quiz - 3 Questions

What is the purpose of extracting the user ID in the first request?

A To set the request method

B To verify the response status code

C To use it in the next request URL to get specific user details

D To check the server availability

Key Result

Always extract dynamic data from one API response and reuse it in subsequent requests to create reliable and connected tests.

Practice

1. What is the main purpose of extracting data from one Postman response to use in the next request?

easy

A. To speed up the test execution by skipping requests

B. To automatically generate random data for requests

C. To avoid writing tests for each request separately

D. To simulate real workflows where requests depend on each other

Solution

1. Step 1: Understand data dependency in workflows

   In real APIs, some requests need data from previous responses to work correctly.

2. Step 2: Recognize the role of data extraction

   Extracting data lets you pass dynamic values from one request to the next, simulating real user flows.

3. Final Answer:

   To simulate real workflows where requests depend on each other -> Option D

4. Quick Check:

   Data extraction = simulate dependent requests [OK]

Hint: Remember: Extract to reuse data in next request [OK]

Common Mistakes:

• Thinking extraction speeds up tests by skipping requests
• Believing extraction replaces writing tests
• Confusing extraction with random data generation

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

easy

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

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

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

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

Solution

1. Step 1: Identify correct method to set environment variable

   The correct method is pm.environment.set to save a variable in environment scope.

2. Step 2: Check syntax correctness

   pm.environment.set('userId', pm.response.json().id); uses pm.environment.set('userId', pm.response.json().id); which is correct syntax and usage.

3. Final Answer:

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

4. Quick Check:

   Use pm.environment.set() to save variables [OK]

Hint: Use pm.environment.set('var', value) to save data [OK]

Common Mistakes:

• Using pm.setEnvironment which does not exist
• Using pm.environment.save which is invalid
• Using pm.variables.set which sets local variables, not environment

3. Given this test script in Postman after a response:

pm.environment.set('token', pm.response.json().authToken);

And the next request uses the header:

Authorization: Bearer {{token}}

What will be the value of the Authorization header if the response JSON is {"authToken": "abc123"}?

medium

A. Authorization: Bearer {{token}}

B. Authorization: Bearer abc123

C. Authorization: Bearer pm.response.json().authToken

D. Authorization: Bearer

Solution

1. Step 1: Extract token from response JSON

   The script saves the value of authToken which is "abc123" into environment variable token.

2. Step 2: Use environment variable in next request header

   The header uses {{token}} which Postman replaces with the saved value "abc123".

3. Final Answer:

   Authorization: Bearer abc123 -> Option B

4. Quick Check:

   {{token}} replaced by saved value [OK]

Hint: Saved variables replace {{var}} placeholders automatically [OK]

Common Mistakes:

• Expecting {{token}} to remain as literal text
• Using wrong variable name causing empty header
• Confusing script syntax with header value

4. You wrote this test script to save a user ID:

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

But the next request using {{userId}} fails with an empty value. What is the most likely cause?

medium

A. The JSON path is incorrect; user ID is at pm.response.json().id, not pm.response.json().user.id

B. You must use pm.variables.set instead of pm.environment.set

C. You forgot to add double curly braces around userId in the next request

D. Environment variables cannot be used in headers

Solution

1. Step 1: Check JSON path correctness

   If the response JSON has user ID at id root, then pm.response.json().user.id is wrong and returns undefined.

2. Step 2: Understand effect of wrong path

   Saving undefined sets empty variable, so {{userId}} is empty in next request causing failure.

3. Final Answer:

   The JSON path is incorrect; user ID is at pm.response.json().id, not pm.response.json().user.id -> Option A

4. Quick Check:

   Correct JSON path = correct variable value [OK]

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

Common Mistakes:

• Using wrong JSON path causing undefined variable
• Confusing pm.variables.set with pm.environment.set
• Forgetting to use {{}} in next request
• Thinking environment variables can't be used in headers

5. You want to extract a session ID from a login response and use it in the next request's URL as a path parameter. The login response JSON is:

{"session": {"id": "sess789"}}

Which is the correct way to extract and use this session ID in the next request URL https://api.example.com/data/{{sessionId}}?

hard

A. In test script: pm.environment.set('sessionId', pm.response.json().session.id); Use URL with {{sessionId}}

B. In test script: pm.variables.set('sessionId', pm.response.json().session.id); Use URL with {{sessionId}}

C. In test script: pm.environment.set('sessionId', pm.response.json().id); Use URL with {{sessionId}}

D. In test script: pm.environment.set('sessionId', pm.response.json().sessionId); Use URL with {{sessionId}}

Solution

1. Step 1: Extract session ID correctly from nested JSON

   The session ID is at pm.response.json().session.id, so use this path to extract it.

2. Step 2: Save to environment variable and use in URL

   Use pm.environment.set('sessionId', ...) to save it, then use {{sessionId}} in the next request URL.

3. Final Answer:

   In test script: pm.environment.set('sessionId', pm.response.json().session.id); Use URL with {{sessionId}} -> Option A

4. Quick Check:

   Correct path + environment set + {{var}} usage [OK]

Hint: Match JSON path exactly and use pm.environment.set [OK]

Common Mistakes:

• Using wrong JSON path like pm.response.json().id
• Using pm.variables.set which is temporary
• Using incorrect variable name in URL
• Extracting from wrong JSON key