Why status codes communicate outcomes in Rest API - Quick Recap

Recall & Review

beginner

What is the main purpose of HTTP status codes in REST APIs?

HTTP status codes tell the client if a request was successful or if there was a problem. They communicate the outcome clearly and quickly.

beginner

What does a 200 status code mean?

A 200 status code means the request was successful and the server sent back the requested data.

intermediate

Why is it important for status codes to be standardized?

Standardized status codes let different systems understand each other easily without confusion, like a common language for success or errors.

beginner

What category of status codes indicates client errors?

Status codes in the 400 range (like 404) indicate client errors, meaning the client sent a bad request or asked for something that doesn't exist.

intermediate

How do status codes help developers during debugging?

Status codes quickly show if a request failed and why, helping developers find and fix problems faster.

What does a 404 status code usually mean?

A The request was successful

B The requested resource was not found

C The server is busy

D The client is unauthorized

A 404 status code means the server could not find the requested resource.

Which status code indicates a successful HTTP request?

A 500

B 301

C 403

D 200

200 means the request was successful and the server returned the expected response.

Why do REST APIs use status codes?

A To communicate the outcome of requests

B To encrypt data

C To store user data

D To speed up the server

Status codes communicate whether a request succeeded or failed and why.

Which status code category signals server errors?

A 500s

B 100s

C 300s

D 200s

Status codes in the 500s indicate server errors.

What does a 401 status code mean?

A Request timeout

B Resource moved permanently

C Unauthorized access

D Bad request syntax

401 means the client must authenticate to get the requested resource.

Explain why HTTP status codes are important for communicating outcomes in REST APIs.

Think about how a simple number can tell if a request worked or not.

Describe the difference between 4xx and 5xx status codes and what they tell the client.

Who caused the problem: client or server?

Practice

1. What is the main purpose of HTTP status codes in REST APIs?

easy

A. To style the webpage content

B. To communicate the outcome of a server request

C. To store user data on the server

D. To encrypt the data sent between client and server

Solution

1. Step 1: Understand the role of status codes

   Status codes are 3-digit numbers sent by the server to tell the client if the request was successful or if there was an error.

2. Step 2: Identify the correct purpose

   They do not style content, store data, or encrypt data; their main job is to communicate the outcome of the request.

3. Final Answer:

   To communicate the outcome of a server request -> Option B

4. Quick Check:

   Status codes = communicate outcome [OK]

Hint: Status codes show if request worked or failed [OK]

Common Mistakes:

• Thinking status codes style pages
• Confusing status codes with data storage
• Assuming status codes encrypt data

2. Which of the following is the correct syntax to send a 404 status code in a REST API response?

easy

A. response.status(404).send('Not Found')

B. response.code(404).send('Not Found')

C. response.sendStatus(200)

D. response.statusCode(500).send('Error')

Solution

1. Step 1: Recall correct method to set status code

   In many REST frameworks, the method to set status code is status(), not code() or statusCode().

2. Step 2: Match status code and message

   404 means 'Not Found', so response.status(404).send('Not Found') is correct syntax.

3. Final Answer:

   response.status(404).send('Not Found') -> Option A

4. Quick Check:

   Use status() to set code [OK]

Hint: Use response.status(code) to set HTTP status [OK]

Common Mistakes:

• Using response.code() instead of response.status()
• Sending wrong status code for error
• Mixing status code and message methods

3. Consider this code snippet in a REST API handler:

if (userFound) {
  res.status(200).json({ message: 'User found' });
} else {
  res.status(404).json({ error: 'User not found' });
}

What will be the HTTP status code if the user is not found?

medium

A. 500

B. 200

C. 404

D. 400

Solution

1. Step 1: Analyze the condition when user is not found

   If userFound is false, the else block runs, sending status 404.

2. Step 2: Identify the status code sent in else block

   The else block uses res.status(404), which means 'Not Found'.

3. Final Answer:

   404 -> Option C

4. Quick Check:

   User missing = 404 status [OK]

Hint: 404 means resource not found [OK]

Common Mistakes:

• Confusing 404 with 200 success
• Assuming 500 server error instead
• Mixing 400 bad request with 404

4. This REST API code tries to send a 201 status but has a bug:

res.sendStatus(201).json({ message: 'Created' });

What is the error and how to fix it?

medium

A. Change 201 to 200 to fix the bug

B. Use res.send(201).json(...) to fix it

C. No error; code works fine

D. sendStatus ends response; use res.status(201).json(...) instead

Solution

1. Step 1: Understand sendStatus behavior

   sendStatus(201) sends the status and ends the response immediately, so chaining .json() after it causes an error.

2. Step 2: Correct way to send status with JSON

   Use res.status(201).json(...) to set status and send JSON in one response.

3. Final Answer:

   sendStatus ends response; use res.status(201).json(...) instead -> Option D

4. Quick Check:

   sendStatus ends response; use status() + json() [OK]

Hint: sendStatus ends response; use status() before json() [OK]

Common Mistakes:

• Chaining json() after sendStatus()
• Using send(201) instead of status(201)
• Changing status code instead of fixing method

5. You want your REST API to return a 204 status code when a DELETE request succeeds but with no content in the response body. Which code snippet correctly implements this?

hard

A. res.status(204).send();

B. res.status(204).json({ message: 'Deleted' });

C. res.sendStatus(204).json({ message: 'Deleted' });

D. res.status(200).send('Deleted');

Solution

1. Step 1: Understand 204 status meaning

   204 means 'No Content', so the response must not include a body.

2. Step 2: Choose code that sends 204 with no body

   res.status(204).send(); sends status 204 with empty body, which is correct. Sending JSON or message body breaks 204 rules.

3. Final Answer:

   res.status(204).send(); -> Option A

4. Quick Check:

   204 = no content, so send empty response [OK]

Hint: 204 means no content; send empty response [OK]

Common Mistakes:

• Sending JSON body with 204 status
• Using 200 instead of 204 for delete success
• Chaining json() after sendStatus(204)