404 Not Found in Rest API - Mini Project: Build & Apply

Handling 404 Not Found in a REST API

📖 Scenario: You are building a simple REST API for a bookstore. Users can request information about books by their ID. If a book is not found, the API should respond with a 404 Not Found error.

🎯 Goal: Create a REST API endpoint that returns book details by ID. If the book ID does not exist, return a 404 Not Found response with a clear message.

📋 What You'll Learn

Create a dictionary called books with exact book IDs and titles

Create a variable called requested_id with the ID to look up

Write code to check if requested_id is in books

If found, return the book title; if not, return a 404 Not Found message

Print the final response

💡 Why This Matters

🌍 Real World

APIs often need to tell users when requested data is missing. Returning a 404 Not Found status is a standard way to do this.

💼 Career

Understanding how to handle missing data and return proper error messages is essential for backend developers and API designers.

1

Create the books data

Create a dictionary called books with these exact entries: 1: 'The Great Gatsby', 2: '1984', 3: 'To Kill a Mockingbird'.

Rest API

# Create the books dictionary with IDs and titles
# Your code here

Need a hint?

Use curly braces to create a dictionary with integer keys and string values.

2

Set the requested book ID

Create a variable called requested_id and set it to 4 to simulate a user requesting a book that does not exist.

Rest API

books = {1: 'The Great Gatsby', 2: '1984', 3: 'To Kill a Mockingbird'}
# Set the requested book ID to 4
# Your code here

Need a hint?

Assign the number 4 to the variable requested_id.

3

Check if the book exists and prepare response

Write an if statement to check if requested_id is in books. If yes, create a variable response with the book title. Otherwise, set response to the string '404 Not Found: Book does not exist.'.

Rest API

books = {1: 'The Great Gatsby', 2: '1984', 3: 'To Kill a Mockingbird'}
requested_id = 4
# Check if requested_id is in books and set response accordingly
# Your code here

Need a hint?

Use if requested_id in books: to check existence, then assign response accordingly.

4

Print the response

Write a print statement to display the response variable.

Rest API

books = {1: 'The Great Gatsby', 2: '1984', 3: 'To Kill a Mockingbird'}
requested_id = 4
if requested_id in books:
    response = books[requested_id]
else:
    response = '404 Not Found: Book does not exist.'
# Print the response
# Your code here

Need a hint?

Use print(response) to show the message.