Expiration-based caching in Rest API - Mini Project: Build & Apply

Expiration-based caching in a REST API

📖 Scenario: You are building a simple REST API that returns data about products. To make your API faster and reduce repeated work, you want to add a cache that stores results temporarily. The cache should keep data only for a short time, then remove it automatically.

🎯 Goal: Build a basic expiration-based cache for your REST API. You will create a cache dictionary, set an expiration time, store data with timestamps, and return cached data only if it is still fresh.

📋 What You'll Learn

Create a cache dictionary to store product data and timestamps

Add a variable for cache expiration time in seconds

Write logic to check if cached data is still valid before returning it

Print the cached data or a message if cache expired

💡 Why This Matters

🌍 Real World

APIs often use caching to speed up responses and reduce repeated work. Expiration-based caching helps keep data fresh while saving resources.

💼 Career

Understanding caching is important for backend developers and API designers to build efficient and scalable web services.

1

Create the cache dictionary

Create a dictionary called cache that will store cached product data and their timestamps. Initialize it as an empty dictionary.

Rest API

# Create an empty dictionary called cache
# Your code here

Need a hint?

Use {} to create an empty dictionary in Python.

2

Set the cache expiration time

Create a variable called cache_expiration and set it to 10. This number means the cache will keep data for 10 seconds before it expires.

Rest API

cache = {}
# Set cache_expiration to 10 seconds
# Your code here

Need a hint?

Just assign the number 10 to the variable cache_expiration.

3

Add caching logic with expiration check

Write code to store product data in cache with the current time, and check if cached data is still valid before returning it. Use variables product_id set to 101 and product_data set to {'name': 'Book', 'price': 12.99}. Use time.time() to get the current time. If cached data exists and is not expired, use it. Otherwise, update the cache with new data and timestamp.

Rest API

cache = {}
cache_expiration = 10
import time

product_id = 101
product_data = {'name': 'Book', 'price': 12.99}

# Your code here

Need a hint?

Use time.time() to get current time and store it with the data in the cache dictionary.

4

Print the cached result

Write a print statement to display the cached_result variable.

Rest API

cache = {}
cache_expiration = 10
import time

product_id = 101
product_data = {'name': 'Book', 'price': 12.99}

current_time = time.time()
if product_id in cache and current_time - cache[product_id]['timestamp'] < cache_expiration:
    cached_result = cache[product_id]['data']
else:
    cache[product_id] = {'data': product_data, 'timestamp': current_time}
    cached_result = product_data

# Print the cached_result
# Your code here

Need a hint?

Use print(cached_result) to show the cached data.