Extracting data from responses in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Extracting a single value from JSON response

Given the following Postman test script, what will be the value of userId after execution if the response body is {"user":{"id":42,"name":"Alice"}}?

Postman

const responseJson = pm.response.json();
const userId = responseJson.user.id;

A "42"

B undefined

C null

D 42

💡 Hint

Remember that JSON numbers are parsed as numbers, not strings.

The response JSON has a user object with an id property of number 42. Accessing responseJson.user.id returns the number 42.

❓ assertion

intermediate

Correct assertion to check extracted value

Which Postman test assertion correctly verifies that the extracted token from the JSON response {"auth":{"token":"abc123"}} is exactly "abc123"?

Postman

const responseJson = pm.response.json();
const token = responseJson.auth.token;

A pm.test('Token is abc123', () => { pm.expect(token).to.be.a('number'); });

B pm.test('Token is abc123', () => { pm.expect(token).to.be.true; });

C pm.test('Token is abc123', () => { pm.expect(token).to.eql('abc123'); });

D pm.test('Token is abc123', () => { pm.expect(token).to.have.length(5); });

💡 Hint

Check the exact value and type of the token string.

Option C correctly asserts that token equals the string 'abc123'. Other options check unrelated conditions.

🔧 Debug

advanced

Debugging extraction from nested JSON array

You want to extract the id of the first item in the items array from this response: {"data":{"items":[{"id":10},{"id":20}]}}. The code below returns undefined. What is the problem?

Postman

const responseJson = pm.response.json();
const firstItemId = responseJson.items[0].id;

A The code should access responseJson.data.items[0].id instead of responseJson.items[0].id.

B The responseJson is not parsed correctly; use pm.response.text() instead.

C The items array is empty, so accessing index 0 returns undefined.

D The id property does not exist on the items objects.

💡 Hint

Check the full path to the items array in the JSON structure.

The items array is inside the data property, so the correct path is responseJson.data.items[0].id.

🧠 Conceptual

advanced

Understanding Postman environment variable extraction

Which statement correctly describes how to extract a value from a JSON response and save it as an environment variable in Postman?

A Use pm.environment.set('varName', value) after extracting the value from pm.response.json().

B Use pm.variables.get('varName') to save the extracted value.

C Use pm.response.save('varName', value) to store the value.

D Use pm.request.set('varName', value) to save the extracted value.

💡 Hint

Remember the method to set environment variables in Postman scripts.

pm.environment.set('varName', value) saves a variable in the environment scope for later use.

❓ framework

expert

Choosing the correct Postman test script for conditional extraction

You want to extract the sessionId from the response only if the status code is 200. Which Postman test script correctly implements this conditional extraction?

A if (pm.response.statusCode === 200) { const sessionId = pm.response.json().sessionId; pm.environment.set('sessionId', sessionId); }

B if (pm.response.code === 200) { const sessionId = pm.response.json().sessionId; pm.environment.set('sessionId', sessionId); }

C if (pm.response.code == '200') { const sessionId = pm.response.json().sessionId; pm.environment.set('sessionId', sessionId); }

D if (pm.response.status === 200) { const sessionId = pm.response.json().sessionId; pm.environment.set('sessionId', sessionId); }

💡 Hint

Check the exact property name for status code in Postman response object.

pm.response.code is the correct property for the numeric status code. pm.response.status is a string like 'OK'.