Header-based versioning in Rest API - Mini Project: Build & Apply

Header-based Versioning in a REST API

📖 Scenario: You are building a simple REST API for a book store. You want to support different versions of the API using HTTP headers. This way, clients can specify which version of the API they want to use by sending a custom header.

🎯 Goal: Create a REST API endpoint that returns book information. Implement header-based versioning so that when the client sends X-API-Version: 1, the API returns the book title only, and when the client sends X-API-Version: 2, the API returns the book title and author.

📋 What You'll Learn

Create a dictionary called book with keys title and author and values 'The Great Gatsby' and 'F. Scott Fitzgerald' respectively.

Create a variable called version_header that simulates reading the 'X-API-Version' header from a request.

Use an if-elif-else statement to check the value of version_header and create a dictionary called response with the correct data for version 1 or 2.

Print the response dictionary.

💡 Why This Matters

🌍 Real World

APIs often need to support multiple versions so that old clients keep working while new features are added. Header-based versioning is one way to do this cleanly.

💼 Career

Understanding how to handle API versioning is important for backend developers and anyone working with web services to ensure smooth upgrades and backward compatibility.

1

DATA SETUP: Create the book data

Create a dictionary called book with these exact entries: 'title': 'The Great Gatsby' and 'author': 'F. Scott Fitzgerald'.

Rest API

# Create the book dictionary with title and author
# Your code here

Hint

Use curly braces {} to create a dictionary with the keys and values exactly as shown.

2

CONFIGURATION: Simulate reading the version header

Create a variable called version_header and set it to the string '1' to simulate the 'X-API-Version' header value.

Rest API

book = {'title': 'The Great Gatsby', 'author': 'F. Scott Fitzgerald'}
# Create version_header variable with value '1'
# Your code here

Hint

Assign the string '1' to the variable version_header.

3

CORE LOGIC: Create response based on version header

Use an if-elif-else statement to check if version_header is '1' or '2'. Create a dictionary called response that contains only 'title' from book if version is '1', or both 'title' and 'author' if version is '2'. If the version is neither, set response to {'error': 'Unsupported API version'}.

Rest API

book = {'title': 'The Great Gatsby', 'author': 'F. Scott Fitzgerald'}
version_header = '1'
# Use if-elif-else to create response dictionary based on version_header
# Your code here

Hint

Use if to check for version '1', elif for version '2', and else for unsupported versions.

4

OUTPUT: Print the response

Write a print statement to display the response dictionary.

Rest API

book = {'title': 'The Great Gatsby', 'author': 'F. Scott Fitzgerald'}
version_header = '1'

if version_header == '1':
    response = {'title': book['title']}
elif version_header == '2':
    response = {'title': book['title'], 'author': book['author']}
else:
    response = {'error': 'Unsupported API version'}

# Print the response dictionary
# Your code here

Hint

Use print(response) to show the final output.

Practice

1. What is the main purpose of header-based versioning in REST APIs?

easy

A. To change the API URL structure for each version

B. To specify the API version using HTTP headers instead of URLs

C. To embed version info inside the request body

D. To use query parameters for version control

Solution

1. Step 1: Understand header-based versioning concept

   Header-based versioning uses HTTP headers to indicate which API version the client wants.

2. Step 2: Compare with other versioning methods

   Unlike URL or query parameter versioning, header-based keeps URLs clean and uses headers instead.

3. Final Answer:

   To specify the API version using HTTP headers instead of URLs -> Option B

4. Quick Check:

   Header versioning = version in HTTP headers [OK]

Hint: Remember: header versioning hides version in HTTP headers [OK]

Common Mistakes:

• Confusing header versioning with URL versioning
• Thinking version is in request body
• Assuming query parameters are used

2. Which HTTP header is commonly used to specify API version in header-based versioning?

easy

A. Content-Type

B. User-Agent

C. Accept

D. Authorization

Solution

1. Step 1: Identify common headers for versioning

   The Accept header is often used to specify the desired API version by content negotiation.

2. Step 2: Exclude unrelated headers

   Content-Type specifies data format sent, Authorization is for credentials, and User-Agent identifies client software.

3. Final Answer:

   Accept -> Option C

4. Quick Check:

   Version in Accept header = D [OK]

Hint: Version info usually goes in the Accept header [OK]

Common Mistakes:

• Using Content-Type instead of Accept for versioning
• Confusing Authorization with version header
• Thinking User-Agent controls version

3. Given this HTTP request header:
Accept: application/vnd.example.v2+json
Which API version is the client requesting?

medium

A. Version 2

B. Version 1

C. Version 3

D. No version specified

Solution

1. Step 1: Parse the Accept header value

   The value application/vnd.example.v2+json includes v2, indicating version 2.

2. Step 2: Confirm version number meaning

   The v2 part is a common pattern to specify version 2 of the API.

3. Final Answer:

   Version 2 -> Option A

4. Quick Check:

   v2 in Accept header means version 2 [OK]

Hint: Look for 'v' followed by number in Accept header [OK]

Common Mistakes:

• Ignoring the 'v2' part and guessing version 1
• Assuming no version if not in URL
• Confusing +json suffix with version

4. A developer wrote this code snippet to check API version from headers:

version = request.headers.get('Content-Type')
if version == 'application/vnd.example.v1+json':
    return 'Version 1'
else:
    return 'Unknown version'

What is the main issue here?

medium

A. Using request.headers.get instead of request.get_header

B. Comparing version string incorrectly

C. Missing else condition

D. Using Content-Type header instead of Accept header for versioning

Solution

1. Step 1: Identify header used for versioning

   Header-based versioning typically uses the Accept header, not Content-Type.

2. Step 2: Explain why Content-Type is wrong here

   Content-Type describes the data format sent by the client, not the requested API version.

3. Final Answer:

   Using Content-Type header instead of Accept header for versioning -> Option D

4. Quick Check:

   Version header should be Accept, not Content-Type [OK]

Hint: Version info is in Accept header, not Content-Type [OK]

Common Mistakes:

• Checking Content-Type for version info
• Assuming request.headers.get is invalid
• Ignoring else branch

5. You want to support two API versions (v1 and v2) simultaneously using header-based versioning. Which approach correctly handles this in your server code?

hard

A. Check the Accept header for 'application/vnd.example.v1+json' or 'application/vnd.example.v2+json' and route accordingly

B. Use URL paths like /v1/resource and /v2/resource to separate versions

C. Ignore headers and always serve the latest version

D. Use query parameters like ?version=1 or ?version=2 to select version

Solution

1. Step 1: Understand header-based versioning goal

   It requires checking the HTTP headers to determine which API version to serve.

2. Step 2: Identify correct version detection method

   Checking the Accept header for specific version strings and routing requests accordingly is the right approach.

3. Final Answer:

   Check the Accept header for 'application/vnd.example.v1+json' or 'application/vnd.example.v2+json' and route accordingly -> Option A

4. Quick Check:

   Route by Accept header version strings [OK]

Hint: Route requests by Accept header version values [OK]

Common Mistakes:

• Mixing header versioning with URL or query parameter versioning
• Ignoring version headers and serving one version only
• Using wrong headers for version detection