Status codes and headers in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a 201 status code in a NestJS controller method.

NestJS

return response.status([1]).send('Created');

Drag options to blanks, or click blank then click option'

A201

B200

C404

D500

Attempts:

3 left

💡 Hint

Common Mistakes

Using 200 instead of 201 for resource creation.

Using error codes like 404 or 500 by mistake.

The status code 201 means 'Created'. It tells the client that a new resource was successfully created.

2fill in blank

medium

Complete the code to set a custom header 'X-Custom-Header' with value 'NestJS' in the response.

NestJS

response.[1]('X-Custom-Header', 'NestJS');

Drag options to blanks, or click blank then click option'

Asend

BsetHeader

Cheader

Dset

Attempts:

3 left

💡 Hint

Common Mistakes

Using send instead of set to set headers.

Using setHeader which is not a NestJS response method.

The set method sets headers in the response object in NestJS.

3fill in blank

hard

Fix the error in setting the status code and sending JSON response.

NestJS

return response.[1](200).json({ message: 'OK' });

Drag options to blanks, or click blank then click option'

Asend

Bstatus

Cset

Dheader

Attempts:

3 left

💡 Hint

Common Mistakes

Using send to set status code causes errors.

Using set or header instead of status.

The status method sets the HTTP status code before sending the response.

4fill in blank

hard

Fill both blanks to set status 404 and a custom header 'X-Error' with value 'NotFound'.

NestJS

return response.[1](404).[2]('X-Error', 'NotFound').send();

Drag options to blanks, or click blank then click option'

Astatus

Bset

Cheader

Dsend

Attempts:

3 left

💡 Hint

Common Mistakes

Using header instead of set for headers.

Using send to set status code.

Use status to set the status code and set to add headers.

5fill in blank

hard

Fill all three blanks to set status 204, add header 'X-Info' with 'No Content', and send the response.

NestJS

return response.[1](204).[2]('X-Info', 'No Content').[3]();

Drag options to blanks, or click blank then click option'

Astatus

Bset

Csend

Djson

Attempts:

3 left

💡 Hint

Common Mistakes

Using json with 204 status which should have no body.

Using header instead of set.

Use status to set status, set to add header, and send to send the response.

Practice

1. In NestJS, what does the HTTP status code 201 usually indicate in a response?

easy

A. A new resource was successfully created

B. The request was malformed or invalid

C. The requested resource was not found

D. The server encountered an internal error

Solution

1. Step 1: Understand HTTP status codes

   HTTP status codes communicate the result of a client's request. Code 201 means "Created".

2. Step 2: Match 201 with its meaning

   201 specifically means a new resource was successfully created on the server.

3. Final Answer:

   A new resource was successfully created -> Option A

4. Quick Check:

   201 = Created [OK]

Hint: 201 means resource created successfully [OK]

Common Mistakes:

• Confusing 201 with 404 (not found)
• Thinking 201 means server error
• Mixing 201 with 400 (bad request)

2. Which of the following is the correct way to set a custom header X-Custom-Header with value 123 in a NestJS controller using Express response?

easy

A. res.setHeader('X-Custom-Header', 789);

B. res.set('X-Custom-Header', '123');

C. res.header('X-Custom-Header', '789');

D. res.addHeader('X-Custom-Header', '123');

Solution

1. Step 1: Recall Express response methods

   Express response object uses res.set() to set headers.

2. Step 2: Check method and value types

   res.set() accepts header name and string value. res.set('X-Custom-Header', '123'); uses correct method and string value.

3. Final Answer:

   res.set('X-Custom-Header', '123'); -> Option B

4. Quick Check:

   Use res.set() to set headers [OK]

Hint: Use res.set() to set headers in NestJS [OK]

Common Mistakes:

• Using res.setHeader (not Express method)
• Passing number instead of string as header value
• Using non-existent res.addHeader method

3. What will be the HTTP status code and header in the response when this NestJS controller method runs?

async getData(@Res() res) {
  res.status(204).set('X-Info', 'No Content').send();
}

medium

A. Status 204 with no headers

B. Status 200 with header X-Info: No Content

C. Status 204 with header X-Info: No Content

D. Status 404 with header X-Info: No Content

Solution

1. Step 1: Analyze status and header setting

   The code sets status to 204 and header 'X-Info' to 'No Content'.

2. Step 2: Understand 204 status behavior

   Status 204 means "No Content" and allows custom headers. The header is set correctly.

3. Final Answer:

   Status 204 with header X-Info: No Content -> Option C

4. Quick Check:

   Status 204 + header set = Status 204 with header X-Info: No Content [OK]

Hint: res.status(204).set() sets status and headers [OK]

Common Mistakes:

• Assuming 204 means no headers allowed
• Confusing default status 200 with explicit 204
• Ignoring header set after status

4. Identify the error in this NestJS controller method that tries to set status and headers:

async update(@Res() res) {
  res.status(200);
  res.set('Content-Type', 'application/json');
  res.send({ success: true });
  res.status(201);
}

medium

A. Calling res.status(201) after res.send() has no effect

B. res.set() must be called before res.status()

C. res.send() cannot send JSON objects

D. res.status() cannot be called twice

Solution

1. Step 1: Review response flow

   res.send() sends the response and ends it. Any code after it won't affect response.

2. Step 2: Check status calls order

   Calling res.status(201) after res.send() does nothing because response is already sent.

3. Final Answer:

   Calling res.status(201) after res.send() has no effect -> Option A

4. Quick Check:

   res.send() ends response, later status calls ignored [OK]

Hint: Set status before res.send(), not after [OK]

Common Mistakes:

• Trying to set status after sending response
• Thinking res.send() can't send JSON
• Believing res.set() must come before res.status()

5. You want to send a 202 Accepted status with a custom header X-Request-ID and a JSON body in NestJS. Which code snippet correctly achieves this?

hard

A. res.send({ message: 'Accepted' }).status(202).set('X-Request-ID', requestId);

B. res.set('X-Request-ID', requestId).status(202).send('Accepted');

C. res.status(202).send({ message: 'Accepted' }).set('X-Request-ID', requestId);

D. res.status(202).set('X-Request-ID', requestId).json({ message: 'Accepted' });

Solution

1. Step 1: Order of method calls matters

   In Express, chaining status, set, and json works if status is set before sending.

2. Step 2: Check each option's correctness

   Options A and C call send before completing status/header setup, invalid. res.set('X-Request-ID', requestId).status(202).send('Accepted'); sets header and status but uses res.send('Accepted') sending plain text instead of JSON object. res.status(202).set('X-Request-ID', requestId).json({ message: 'Accepted' }); correctly sets status, header, sends JSON.

3. Step 3: Confirm best practice

   res.status(202).set('X-Request-ID', requestId).json({ message: 'Accepted' }); is the clearest and most common pattern: status, set header, then send JSON.

4. Final Answer:

   res.status(202).set('X-Request-ID', requestId).json({ message: 'Accepted' }); -> Option D

5. Quick Check:

   Status then headers then send JSON [OK]

Hint: Chain status, set, then send/json in that order [OK]

Common Mistakes:

• Calling send before setting status or headers
• Using send instead of json for JSON body
• Setting headers after sending response