PUT request in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding PUT request idempotency

Which statement best describes the idempotency property of a PUT request in REST API testing?

A A PUT request always creates a new resource regardless of repetition.

B A PUT request can be repeated multiple times with the same effect as a single request.

C A PUT request cannot be repeated without causing errors.

D A PUT request is used only for retrieving data without changes.

💡 Hint

Think about what happens if you send the same update multiple times.

PUT requests are idempotent, meaning sending the same request multiple times results in the same state as sending it once.

❓ Predict Output

intermediate

Output of a PUT request test in Postman

Given this Postman test script for a PUT request, what will be the test result?

Postman

pm.test('Status code is 200', function () {
    pm.response.to.have.status(200);
});
pm.test('Response body has updated name', function () {
    var jsonData = pm.response.json();
    pm.expect(jsonData.name).to.eql('Alice');
});

A Both tests fail if the response body is empty.

B The tests pass regardless of response content.

C The first test fails if status is 200, second test always passes.

D Both tests pass if the server returns status 200 and the updated name 'Alice'.

💡 Hint

Check what each test is verifying in the response.

The first test checks the HTTP status code is 200. The second test checks the JSON response has the updated name 'Alice'. Both must be true to pass.

❓ locator

advanced

Best locator for verifying PUT request response field

In Postman test scripts, which is the best way to access the 'email' field from a JSON response after a PUT request?

A var email = pm.response.json().email;

B var email = pm.response.body.email;

C var email = pm.response.get('email');

D var email = pm.response.text().email;

💡 Hint

Consider how to parse JSON response in Postman scripts.

pm.response.json() parses the response body as JSON, allowing direct access to fields like 'email'.

❓ assertion

advanced

Correct assertion for PUT response status and content

Which Postman test assertion correctly verifies the PUT response has status 204 and an empty body?

A pm.test('Status is 204', () => pm.response.to.have.status(204)); pm.test('Body is empty', () => pm.expect(pm.response.text()).to.eql(''));

B pm.test('Status is 204', () => pm.response.to.have.status(204)); pm.test('Body is empty', () => pm.expect(pm.response.json()).to.eql({}));

C pm.test('Status is 204', () => pm.response.to.have.status(204)); pm.test('Body is empty', () => pm.expect(pm.response.body).to.be.null);

D pm.test('Status is 204', () => pm.response.to.have.status(204)); pm.test('Body is empty', () => pm.expect(pm.response.text()).to.be.null);

💡 Hint

Think about how to check an empty response body as text.

pm.response.text() returns the response body as a string. For empty body, it should equal an empty string ''.

❓ framework

expert

Automating PUT request tests with Newman CLI

You want to run a Postman collection with PUT request tests automatically in your CI pipeline using Newman. Which command correctly runs the collection and outputs a JSON report?

A newman start collection.json -r json -o report.json

B newman execute collection.json --output json report.json

C newman run collection.json -r json --reporter-json-export report.json

D newman run collection.json --json-report report.json

💡 Hint

Check Newman documentation for JSON reporter options.

The correct Newman command uses '-r json' to specify JSON reporter and '--reporter-json-export' to set output file.

Practice

1. What is the main purpose of a PUT request in Postman?

easy

A. To update or replace an existing resource on the server

B. To retrieve data from the server

C. To delete a resource from the server

D. To create a new resource without replacing existing data

Solution

1. Step 1: Understand HTTP methods

   PUT is used to update or replace existing data, unlike GET which retrieves data or DELETE which removes data.

2. Step 2: Match PUT request purpose

   PUT requires sending the full new data to replace the existing resource, so it updates or replaces it.

3. Final Answer:

   To update or replace an existing resource on the server -> Option A

4. Quick Check:

   PUT updates/replaces resource = A [OK]

Hint: PUT replaces full resource data, not partial updates [OK]

Common Mistakes:

• Confusing PUT with GET or POST
• Thinking PUT creates new resources only
• Assuming PUT partially updates data

2. Which of the following is the correct way to set up a PUT request body in Postman to update a user's name to "Alice"?

easy

A. { name = "Alice" }

B. [ "name": "Alice" ]

C. "name": "Alice"

D. { "name": "Alice" }

Solution

1. Step 1: Identify correct JSON syntax

   JSON objects use curly braces with key-value pairs in double quotes and colon separators.

2. Step 2: Validate syntax of options

   Only { "name": "Alice" } is valid JSON. The others have syntax errors like using = instead of :, square brackets, or incomplete structure.

3. Final Answer:

   { "name": "Alice" } -> Option D

4. Quick Check:

   Valid JSON body = D [OK]

Hint: Use curly braces and double quotes for JSON body [OK]

Common Mistakes:

• Using square brackets instead of braces
• Missing quotes around keys or values
• Using equals sign instead of colon

3. Given this PUT request in Postman to update a product's price:

{
  "id": 101,
  "name": "Coffee Mug",
  "price": 12.99
}

If the server replaces the entire product resource with this data, what will be the product's name after the update?

medium

A. null

B. Original name before update

C. Coffee Mug

D. Error: Missing fields

Solution

1. Step 1: Understand PUT replaces full resource

   The server replaces the entire product data with the provided JSON, so all fields sent become the new state.

2. Step 2: Check the name field in the request body

   The name is "Coffee Mug" in the JSON, so after update, the product's name will be "Coffee Mug".

3. Final Answer:

   Coffee Mug -> Option C

4. Quick Check:

   PUT replaces resource fully = Coffee Mug [OK]

Hint: PUT replaces all fields sent, so name updates to given value [OK]

Common Mistakes:

• Assuming PUT only updates changed fields
• Thinking missing fields stay unchanged
• Expecting error if some fields are missing

4. You send a PUT request in Postman but receive a 400 Bad Request error. Which of these is the most likely cause?

medium

A. The server does not support PUT requests

B. The request body is missing required fields or has invalid JSON

C. The URL is incorrect but the body is fine

D. The GET method was used instead of PUT

Solution

1. Step 1: Understand 400 Bad Request meaning

   400 error means the server could not understand the request due to invalid syntax or missing data.

2. Step 2: Analyze causes for 400 in PUT requests

   Invalid JSON or missing required fields in the body commonly cause 400 errors for PUT requests.

3. Final Answer:

   The request body is missing required fields or has invalid JSON -> Option B

4. Quick Check:

   400 error = invalid request body [OK]

Hint: Check JSON syntax and required fields for 400 errors [OK]

Common Mistakes:

• Confusing 400 with 404 Not Found
• Assuming server disallows PUT causes 400
• Mixing up HTTP methods in error cause

5. You want to update a user's profile with a PUT request in Postman. The user has fields: id, name, email, and phone. You only want to change the phone number. What is the best practice to avoid accidentally deleting other fields?

hard

A. Include all fields with current values, changing only the phone number in the PUT body

B. Send only the phone field in the PUT body

C. Use a GET request to update the phone number

D. Send an empty body with the PUT request

Solution

1. Step 1: Recall PUT replaces entire resource

   PUT replaces the whole resource with the data sent, so missing fields will be removed.

2. Step 2: Include all fields to preserve data

   To avoid deleting fields, send all current fields with updated phone number in the PUT body.

3. Final Answer:

   Include all fields with current values, changing only the phone number in the PUT body -> Option A

4. Quick Check:

   PUT replaces full data, so send all fields [OK]

Hint: Send full resource data in PUT to avoid data loss [OK]

Common Mistakes:

• Sending partial data with PUT causing data loss
• Using GET to update data
• Sending empty body expecting no changes