Versioning best practices in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this API versioning example?

Consider a REST API that uses URL path versioning. The client requests /api/v2/users. The server code routes this to the version 2 handler, which returns a JSON list of users with an added email field.

What JSON response will the client receive?

Rest API

def get_users(version):
    if version == 'v1':
        return [{'id': 1, 'name': 'Alice'}, {'id': 2, 'name': 'Bob'}]
    elif version == 'v2':
        return [{'id': 1, 'name': 'Alice', 'email': '[e-mail]'}, {'id': 2, 'name': 'Bob', 'email': '[e-mail]'}]

response = get_users('v2')
print(response)

A [{'id': 1, 'name': 'Alice'}, {'id': 2, 'name': 'Bob'}]

B Error: Version not supported

C [{'id': 1, 'name': 'Alice', 'email': '[e-mail]'}, {'id': 2, 'name': 'Bob', 'email': '[e-mail]'}]

D []

💡 Hint

Check which version the function returns with the email field included.

Version 2 adds the email field to each user. Since the client requested v2, the response includes emails.

🧠 Conceptual

intermediate

Which versioning method is best for backward compatibility?

There are several ways to version REST APIs: URL path versioning, query parameter versioning, and header versioning.

Which method is generally considered best for maintaining backward compatibility and clean URLs?

A Using URL path versioning like /api/v1/resource

B Using query parameters like /api/resource?version=1

C Using custom headers like X-API-Version: 1

D No versioning, just update the API directly

💡 Hint

Think about what makes URLs clear and easy to cache.

URL path versioning clearly separates versions and is easy to cache and document, making it best for backward compatibility.

🔧 Debug

advanced

Why does this API versioning code return 'default handler' unexpectedly?

The following Python code tries to parse the API version from a header and route the request. It returns 'default handler' even though the header has value 2. Why?

Rest API

def route_request(headers):
    version = headers.get('X-API-Version')
    if version == '1':
        return 'v1 handler'
    elif version == '2':
        return 'v2 handler'
    else:
        return 'default handler'

headers = {'X-API-Version': 2}
print(route_request(headers))

A SyntaxError due to missing colon

B KeyError because 'X-API-Version' is missing

C TypeError because header value is int, not string

D Returns 'default handler' because version is int, not string

💡 Hint

Check the type of the header value and how it is compared.

The header value is an integer 2, but the code compares it to strings '1' and '2'. Since 2 == '2' is False, it falls to the 'default handler'.

📝 Syntax

advanced

Which option correctly defines a versioned API route in Flask?

Given Flask web framework, which route decorator correctly defines a versioned API endpoint for version 1?

Rest API

from flask import Flask
app = Flask(__name__)

@app.route('/api/v1/users')
def get_users():
    return 'Users v1'

A @app.route('/api/users?version=1')

B @app.route('/api/v1/users')

C @app.route('/api/users/v1')

D @app.route('/api/users', version='1')

💡 Hint

Think about how URL paths are defined in Flask routes.

Flask routes match URL paths literally. Version in the path should come before the resource name for clarity.

🚀 Application

expert

How many distinct API versions are supported by this versioning logic?

Consider this API versioning logic in pseudocode:

if 'version' in request.headers:
    if request.headers['version'] in ['1', '2', '3']:
        use that version
    else:
        use default version 1
else:
    use default version 1

How many distinct API versions can clients explicitly request?

A 3

B 4

C 1

D 0

💡 Hint

Count the versions listed in the allowed list.

The code allows clients to request versions '1', '2', or '3' explicitly. Any other or missing version defaults to '1'.