Request headers (Content-Type, Accept) in Rest API - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the Content-Type header in an HTTP request?

The Content-Type header tells the server the format of the data being sent in the request body, such as application/json or text/html.

beginner

What does the Accept header specify in an HTTP request?

The Accept header tells the server what content types the client can handle in the response, like application/json or text/html.

beginner

If a client sends Content-Type: application/json, what does it mean?

It means the client is sending data in JSON format in the request body, so the server should read it as JSON.

intermediate

Why is it important to set the Accept header correctly?

Setting the Accept header correctly helps the server send back data in a format the client understands, avoiding errors or confusion.

intermediate

What happens if the Content-Type header is missing in a POST request?

The server might not know how to interpret the request body, which can cause errors or unexpected behavior.

What does the Content-Type header in an HTTP request specify?

A The HTTP method used

B The format of the data the client wants to receive

C The server's IP address

D The format of the data sent in the request body

The Content-Type header tells the server the format of the data sent in the request body.

Which header tells the server what response formats the client can accept?

A Accept

B Authorization

C Content-Type

D User-Agent

The Accept header specifies the content types the client can handle in the response.

If a client wants JSON data back from the server, what should the Accept header be set to?

A application/json

B text/plain

C multipart/form-data

D text/html

Setting Accept: application/json tells the server the client wants JSON data.

What might happen if the Content-Type header is incorrect or missing when sending JSON data?

A The client automatically fixes the header

B The client will receive an error immediately

C The server may not parse the data correctly

D The server ignores the request

Without the correct Content-Type, the server may not understand the data format.

Which header would you use to tell the server you are sending form data?

A Accept: application/x-www-form-urlencoded

B Content-Type: application/x-www-form-urlencoded

C Accept: multipart/form-data

D Content-Type: text/plain

The Content-Type header should be set to application/x-www-form-urlencoded when sending form data.

Explain the roles of the Content-Type and Accept headers in an HTTP request.

Think about sending and receiving data formats.

Describe what could go wrong if the Content-Type header is missing or incorrect in a POST request.

Consider how the server reads the data you send.

Practice

1. What does the Content-Type header specify in an HTTP request?

easy

A. The format of the data being sent to the server

B. The format of the data the client wants to receive

C. The server's IP address

D. The HTTP method used in the request

Solution

1. Step 1: Understand the role of Content-Type

   The Content-Type header tells the server what format the request body data is in, such as JSON or XML.

2. Step 2: Differentiate from Accept header

   The Accept header tells the server what response format the client wants, not the data sent.

3. Final Answer:

   The format of the data being sent to the server -> Option A

4. Quick Check:

   Content-Type = request data format [OK]

Hint: Content-Type = your data format sent [OK]

Common Mistakes:

• Confusing Content-Type with Accept header
• Thinking Content-Type is about response format
• Ignoring the header completely

2. Which of the following is the correct way to set the Accept header to request JSON data in an HTTP request?

easy

A. Content-Type: application/json

B. Accept: text/html

C. Accept: application/json

D. Content-Type: text/plain

Solution

1. Step 1: Identify the Accept header usage

   The Accept header tells the server what response format the client wants, such as JSON.

2. Step 2: Match the correct MIME type for JSON

   The MIME type for JSON is application/json, so the header should be Accept: application/json.

3. Final Answer:

   Accept: application/json -> Option C

4. Quick Check:

   Accept header for JSON = application/json [OK]

Hint: Accept header = desired response format [OK]

Common Mistakes:

• Using Content-Type instead of Accept for response format
• Using wrong MIME type like text/html for JSON
• Mixing up header names

3. Given this HTTP request snippet:

POST /api/data HTTP/1.1
Host: example.com
Content-Type: application/json
Accept: application/xml

{"name": "Alice"}

What format will the server expect the request body to be, and what format will it try to respond with?

medium

A. Request body XML, response JSON

B. Request body XML, response XML

C. Request body JSON, response JSON

D. Request body JSON, response XML

Solution

1. Step 1: Analyze Content-Type header

   The Content-Type is application/json, so the server expects JSON data in the request body.

2. Step 2: Analyze Accept header

   The Accept header is application/xml, so the client wants the response in XML format.

3. Final Answer:

   Request body JSON, response XML -> Option D

4. Quick Check:

   Content-Type = JSON, Accept = XML [OK]

Hint: Content-Type = sent data, Accept = wanted response [OK]

Common Mistakes:

• Mixing up Content-Type and Accept roles
• Assuming response matches request format
• Ignoring headers and guessing defaults

4. You wrote this HTTP request:

POST /submit HTTP/1.1
Host: example.com
Content-Type: application/json
Accept: application/json

name=John&age=30

Why might the server reject this request or fail to parse the data?

medium

A. Because the HTTP method POST is not allowed

B. Because the Content-Type says JSON but the body is URL-encoded form data

C. Because Accept header is incorrect for JSON

D. Because the Host header is missing

Solution

1. Step 1: Check Content-Type and body format

   The Content-Type is application/json, but the body is name=John&age=30, which is URL-encoded form data, not JSON.

2. Step 2: Understand server parsing behavior

   The server expects JSON data but receives form data, so it may reject or fail to parse the request.

3. Final Answer:

   Because the Content-Type says JSON but the body is URL-encoded form data -> Option B

4. Quick Check:

   Content-Type must match body format [OK]

Hint: Match Content-Type with actual body format [OK]

Common Mistakes:

• Ignoring mismatch between Content-Type and body
• Assuming Accept header affects request body
• Thinking Host header is missing when it is present

5. You want to send JSON data to an API and receive a JSON response. Which headers should you set correctly in your HTTP request to ensure this communication?

hard

A. Content-Type: application/json and Accept: application/json

B. Content-Type: text/plain and Accept: application/json

C. Content-Type: application/json and Accept: text/html

D. Content-Type: application/xml and Accept: application/json

Solution

1. Step 1: Set Content-Type for request data

   Since you are sending JSON data, set Content-Type: application/json so the server knows the format of the data you send.

2. Step 2: Set Accept for response format

   To receive JSON response, set Accept: application/json to tell the server you want JSON back.

3. Final Answer:

   Content-Type: application/json and Accept: application/json -> Option A

4. Quick Check:

   Both headers set to application/json for JSON exchange [OK]

Hint: Both headers must match JSON for send and receive [OK]

Common Mistakes:

• Setting Content-Type and Accept to different formats
• Using text/plain or XML when JSON is needed
• Forgetting to set Accept header