204 No Content in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the HTTP status code returned?

You send a DELETE request to remove a resource from a REST API. The server successfully deletes the resource but returns no content in the response body.

What HTTP status code should the server return?

A 200 OK

B 204 No Content

C 404 Not Found

D 500 Internal Server Error

💡 Hint

Think about a status code that means success but no response body.

204 No Content means the request was successful but the server has no content to return. It is commonly used for DELETE requests.

🧠 Conceptual

intermediate

Why use 204 No Content instead of 200 OK with empty body?

When a REST API successfully processes a request but has no content to return, why is 204 No Content preferred over 200 OK with an empty response body?

A 200 OK causes the client to retry the request automatically.

B 200 OK is only for GET requests, so it cannot be used here.

C 204 No Content allows caching, 200 OK does not.

D 204 No Content explicitly tells the client there is no body, so it can skip parsing.

💡 Hint

Think about how clients handle response bodies.

204 No Content tells clients explicitly that there is no response body, so clients can avoid unnecessary parsing or rendering.

❓ Predict Output

advanced

What is the output of this Express.js code?

Consider this Node.js Express server code snippet:

app.delete('/item/:id', (req, res) => {
  // Assume item is deleted successfully
  res.status(204).send();
});

What will the client receive as the HTTP status and body?

Rest API

app.delete('/item/:id', (req, res) => {
  // Assume item is deleted successfully
  res.status(204).send();
});

A Status 204 with empty body

B Status 204 with JSON body {"message":"Deleted"}

C Status 200 with empty body

D Status 404 with error message

💡 Hint

Check what res.status(204).send() does.

Setting status 204 and calling send() sends a response with status 204 and no content in the body.

🔧 Debug

advanced

Why does this API client fail to handle 204 response?

This JavaScript fetch client code tries to parse JSON from a 204 No Content response:

fetch('/api/delete/123', { method: 'DELETE' })
  .then(res => res.json())
  .then(data => console.log(data))
  .catch(err => console.error('Error:', err));

What error will occur and why?

Rest API

fetch('/api/delete/123', { method: 'DELETE' })
  .then(res => res.json())
  .then(data => console.log(data))
  .catch(err => console.error('Error:', err));

A SyntaxError because response body is empty and cannot be parsed as JSON

B TypeError because fetch does not support DELETE method

C ReferenceError because 'res' is undefined

D No error, logs empty object

💡 Hint

Think about parsing empty response as JSON.

Calling res.json() on an empty response body causes a SyntaxError because there is no JSON to parse.

🚀 Application

expert

How to correctly handle 204 No Content in a React app fetch call?

You make a DELETE request in a React app using fetch. The server returns 204 No Content. You want to update the UI after deletion without errors.

Which code snippet correctly handles the 204 response?

A

fetch('/api/item/1', { method: 'DELETE' })
  .then(res => {
    if (res.ok) return res.json();
  })
  .then(data => updateUI(data));

B

fetch('/api/item/1', { method: 'DELETE' })
  .then(res => res.json())
  .then(data => updateUI(data));

C

fetch('/api/item/1', { method: 'DELETE' })
  .then(res => {
    if (res.status === 204) return null;
    return res.json();
  })
  .then(data => {
    if (data !== null) updateUI(data);
    else updateUI(null);
  });

D

fetch('/api/item/1', { method: 'DELETE' })
  .then(res => res.text())
  .then(text => updateUI(text));

💡 Hint

Check how to avoid parsing JSON when no content is returned.

Option C checks for 204 status and returns null instead of calling res.json(), avoiding parsing errors. Then it updates UI accordingly.

Practice

1. What does the HTTP status code 204 No Content indicate in a REST API response?

easy

A. The request failed due to a client error.

B. The request was successful but there is no content to return.

C. The server encountered an error processing the request.

D. The resource was created successfully.

Solution

1. Step 1: Understand the meaning of 204 status code

   The 204 status code means the server successfully processed the request but does not return any content in the response body.

2. Step 2: Compare with other status codes

   Other codes like 4xx indicate client errors, 5xx indicate server errors, and 201 indicates resource creation, so they do not match 204's meaning.

3. Final Answer:

   The request was successful but there is no content to return. -> Option B

4. Quick Check:

   204 means success with no content [OK]

Hint: 204 means success but no response body [OK]

Common Mistakes:

• Confusing 204 with 200 OK which usually returns content
• Thinking 204 means an error occurred
• Assuming 204 means resource creation

2. Which of the following is the correct way to send a 204 No Content response in a REST API using HTTP headers?

easy

A. Status: 200 OK\nContent-Length: 0

B. Status: 204 No Content\nContent-Type: application/json

C. Status: 204 No Content\nContent-Length: 0

D. Status: 404 Not Found

Solution

1. Step 1: Identify correct status and headers for 204

   204 No Content must have status line '204 No Content' and usually a 'Content-Length: 0' header to indicate no body.

2. Step 2: Eliminate incorrect options

   Status: 204 No Content\nContent-Type: application/json wrongly includes Content-Type which is unnecessary for no content; Status: 200 OK\nContent-Length: 0 uses 200 OK, not 204; Status: 404 Not Found is unrelated 404 error.

3. Final Answer:

   Status: 204 No Content\nContent-Length: 0 -> Option C

4. Quick Check:

   204 with Content-Length 0 is correct [OK]

Hint: 204 must have Content-Length: 0 header [OK]

Common Mistakes:

• Including Content-Type header unnecessarily
• Using 200 OK instead of 204
• Sending body content with 204 status

3. Consider this REST API code snippet in Python Flask:

from flask import Flask, jsonify, make_response
app = Flask(__name__)

@app.route('/delete_item/', methods=['DELETE'])
def delete_item(id):
    # Assume item is deleted successfully
    return make_response('', 204)

if __name__ == '__main__':
    app.run()

What will be the HTTP status code and response body when a client calls DELETE /delete_item/5?

medium

A. Status code 204 with empty response body

B. Status code 200 with JSON response body

C. Status code 404 with error message

D. Status code 500 with server error

Solution

1. Step 1: Analyze the return statement in the Flask route

   The function returns make_response with empty string and status 204, which means no content is sent back.

2. Step 2: Understand HTTP 204 behavior

   204 status means success with no response body, so the client receives status 204 and empty body.

3. Final Answer:

   Status code 204 with empty response body -> Option A

4. Quick Check:

   Flask returns 204 with no content [OK]

Hint: 204 means success with empty body in Flask [OK]

Common Mistakes:

• Expecting JSON response body with 204
• Confusing 204 with 200 OK
• Assuming error status codes

4. A developer wrote this Express.js code to send a 204 response:

app.delete('/item/:id', (req, res) => {
  res.status(204).send({ message: 'Deleted' });
});

What is the problem with this code regarding the 204 No Content response?

medium

A. 204 responses must not include a response body, but this sends JSON content.

B. The status code should be 200 instead of 204 for delete operations.

C. The route method should be GET, not DELETE.

D. The response is missing a Content-Type header.

Solution

1. Step 1: Understand 204 No Content rules

   204 status means no response body should be sent, but the code sends JSON content in the body.

2. Step 2: Identify the violation in the code

   Calling send() with an object adds a response body, which violates 204 semantics.

3. Final Answer:

   204 responses must not include a response body, but this sends JSON content. -> Option A

4. Quick Check:

   204 must not send body [OK]

Hint: Never send body with 204 status [OK]

Common Mistakes:

• Sending JSON or text body with 204 status
• Using wrong HTTP method for delete
• Confusing 204 with 200 OK

5. You are designing a REST API for updating user profiles. After a successful update, you want to respond with 204 No Content. Which of the following is the best practice to implement this behavior?

hard

A. Return status 204 with a JSON body confirming the update.

B. Return status 201 with a Location header pointing to the updated resource.

C. Return status 200 with the updated user profile in the response body.

D. Return status 204 with an empty response body and no Content-Type header.

Solution

1. Step 1: Understand 204 usage for update operations

   204 No Content is ideal for successful updates when no response body is needed.

2. Step 2: Identify best practice for 204 response

   Best practice is to send status 204 with empty body and omit Content-Type header to avoid confusion.

3. Final Answer:

   Return status 204 with an empty response body and no Content-Type header. -> Option D

4. Quick Check:

   204 means success with no content [OK]

Hint: 204 means success, no body, no Content-Type header [OK]

Common Mistakes:

• Sending JSON body with 204 status
• Using 201 Created for update instead of 204
• Returning 200 OK with body when 204 is preferred