Batch update patterns in Rest API - Mini Project: Build & Apply

Batch Update Patterns with REST API

📖 Scenario: You are building a simple REST API for a bookstore. The store wants to update the prices of multiple books at once to run a sale.Batch updates let you change many items in one request, saving time and effort.

🎯 Goal: Create a batch update endpoint that accepts a list of book IDs and new prices, then updates the prices in the data store.

📋 What You'll Learn

Create a data structure to hold books with their IDs and prices

Add a configuration variable for the discount percentage

Write the batch update logic to apply the discount to selected books

Print the updated books after the batch update

💡 Why This Matters

🌍 Real World

Batch updates are common in online stores to quickly change prices or stock for many products at once.

💼 Career

Understanding batch update patterns helps backend developers build efficient APIs that handle multiple changes in one request.

1

DATA SETUP: Create the initial books data

Create a dictionary called books with these exact entries: 1: {'title': 'Book A', 'price': 100}, 2: {'title': 'Book B', 'price': 150}, 3: {'title': 'Book C', 'price': 200}

Rest API

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

Need a hint?

Use a dictionary with keys as book IDs and values as dictionaries holding title and price.

2

CONFIGURATION: Set the discount percentage

Create a variable called discount_percent and set it to 10 to represent a 10% discount

Rest API

books = {
    1: {'title': 'Book A', 'price': 100},
    2: {'title': 'Book B', 'price': 150},
    3: {'title': 'Book C', 'price': 200}
}
# Set the discount_percent variable
# Your code here

Need a hint?

Just create a variable with the exact name and value.

3

CORE LOGIC: Apply batch update to selected books

Write a function called batch_update_prices that takes book_ids (a list) and updates each book's price in books by reducing it by discount_percent. Use a for loop with book_id to iterate over book_ids and update the price inside the function.

Rest API

books = {
    1: {'title': 'Book A', 'price': 100},
    2: {'title': 'Book B', 'price': 150},
    3: {'title': 'Book C', 'price': 200}
}
discount_percent = 10

# Define batch_update_prices function below
# Your code here

Need a hint?

Use a function with a for loop to update prices by applying the discount.

4

OUTPUT: Run batch update and print updated books

Call batch_update_prices with the list [1, 3] and then print the books dictionary to show updated prices

Rest API

books = {
    1: {'title': 'Book A', 'price': 100},
    2: {'title': 'Book B', 'price': 150},
    3: {'title': 'Book C', 'price': 200}
}
discount_percent = 10

def batch_update_prices(book_ids):
    for book_id in book_ids:
        if book_id in books:
            old_price = books[book_id]['price']
            new_price = old_price * (100 - discount_percent) / 100
            books[book_id]['price'] = round(new_price, 2)

# Call batch_update_prices and print books
# Your code here

Need a hint?

Call the function with the list [1, 3] and print the books dictionary.