Content negotiation in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this HTTP Accept header handling code?

Consider a REST API server that supports JSON and XML responses. The server code snippet below processes the Accept header to decide the response format.

accept_header = 'application/xml,application/json;q=0.9'

if 'application/json' in accept_header:
    response = 'JSON response'
elif 'application/xml' in accept_header:
    response = 'XML response'
else:
    response = 'Default response'

What will be the value of response after running this code?

Rest API

accept_header = 'application/xml,application/json;q=0.9'

if 'application/json' in accept_header:
    response = 'JSON response'
elif 'application/xml' in accept_header:
    response = 'XML response'
else:
    response = 'Default response'

A JSON response

B XML response

C Default response

D Error: header parsing failed

💡 Hint

Check the order of if and elif conditions and how substring matching works.

The code checks if the string 'application/json' is anywhere in the accept_header. Since it is present (after the comma), the first if condition is true, so response is set to 'JSON response'. The elif is not checked after that.

🧠 Conceptual

intermediate

Which HTTP header is primarily used for content negotiation?

In REST APIs, clients specify the desired response format using a specific HTTP header. Which header is this?

A User-Agent

B Authorization

C Content-Type

D Accept

💡 Hint

It tells the server what media types the client can handle.

The Accept header is used by clients to tell the server which content types they prefer. The server uses this to perform content negotiation and respond accordingly.

❓ Predict Output

advanced

What is the output of this server content negotiation snippet?

Given the following Python code snippet simulating content negotiation, what will be printed?

accept_header = 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'

if 'application/json' in accept_header:
    print('Send JSON')
elif 'application/xml' in accept_header:
    print('Send XML')
elif 'text/html' in accept_header:
    print('Send HTML')
else:
    print('Send default')

Rest API

accept_header = 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'

if 'application/json' in accept_header:
    print('Send JSON')
elif 'application/xml' in accept_header:
    print('Send XML')
elif 'text/html' in accept_header:
    print('Send HTML')
else:
    print('Send default')

A Send XML

B Send HTML

C Send JSON

D Send default

💡 Hint

Check the order of conditions and presence of substrings in the header string.

The string 'application/json' is not present, so first if fails. The string 'application/xml' is present (with quality factor), so the second elif is true and prints 'Send XML'. The later conditions are not checked.

🔧 Debug

advanced

Why does this content negotiation code always return JSON?

Look at this Python code snippet:

accept_header = 'application/xml'

if accept_header == 'application/json' or 'application/xml':
    response = 'JSON response'
else:
    response = 'Default response'

Why does response always become 'JSON response' even when accept_header is 'application/xml'?

Rest API

accept_header = 'application/xml'

if accept_header == 'application/json' or 'application/xml':
    response = 'JSON response'
else:
    response = 'Default response'

A Because accept_header is overwritten before the if statement

B Because the code compares accept_header to both strings correctly

C Because 'application/xml' is always truthy, so the condition is always true

D Because the else block is never reached due to syntax error

💡 Hint

Look carefully at how the or operator is used in the condition.

The condition accept_header == 'application/json' or 'application/xml' is evaluated as (accept_header == 'application/json') or ('application/xml'). Since non-empty strings are always true in Python, the condition always evaluates to true, so response is always 'JSON response'.

🚀 Application

expert

How many media types will this content negotiation dictionary contain?

Given this Python dictionary comprehension that parses an Accept header string into media types and their quality factors:

accept_header = 'text/html,application/json;q=0.8,application/xml;q=0.9'

media_types = {part.split(';')[0]: float(part.split('q=')[1]) if 'q=' in part else 1.0 for part in accept_header.split(',')}

print(len(media_types))

What is the output of the print statement?

Rest API

accept_header = 'text/html,application/json;q=0.8,application/xml;q=0.9'

media_types = {part.split(';')[0]: float(part.split('q=')[1]) if 'q=' in part else 1.0 for part in accept_header.split(',')}

print(len(media_types))

A 2

B 3

C 1

D Raises ValueError

💡 Hint

Count how many unique media types are extracted from the header string.

The dictionary comprehension splits the header by commas, then for each part extracts the media type before any semicolon and assigns a quality factor (default 1.0 if missing). The header has three media types: 'text/html', 'application/json', and 'application/xml'. So the dictionary has 3 keys, and len(media_types) is 3.