Response caching strategies in Flask - Mini Project: Build & Apply

Response caching strategies in Flask

📖 Scenario: You are building a simple Flask web app that shows the current time. To make the app faster and reduce server load, you want to add caching strategies to store and reuse responses for a short time.

🎯 Goal: Build a Flask app with a route /time that returns the current time. Add a caching mechanism that stores the response for 10 seconds so repeated requests within that time return the cached response instead of recalculating the time.

📋 What You'll Learn

Create a Flask app with a route /time

Add a cache dictionary to store cached responses

Set a cache timeout of 10 seconds

Implement logic to return cached response if valid

Return fresh response and update cache if expired

💡 Why This Matters

🌍 Real World

Caching responses in web apps improves speed and reduces server load by reusing data instead of recalculating it every time.

💼 Career

Understanding caching strategies is important for backend developers to optimize web app performance and scalability.

1

Set up Flask app and route

Import Flask and datetime. Create a Flask app called app. Define a route /time with a function get_time that returns the current time as a string using datetime.datetime.now().

Flask

from flask import Flask
from datetime import datetime

app = Flask(__name__)

@app.route('/time')
def get_time():
    # Your code here

Need a hint?

Use datetime.now().strftime('%Y-%m-%d %H:%M:%S') to format the current time as a string.

2

Add cache dictionary and timeout

Create a dictionary called cache to store cached responses. Create a variable cache_timeout and set it to 10 seconds.

Flask

from flask import Flask
from datetime import datetime

app = Flask(__name__)

cache = {}
cache_timeout = 10

@app.route('/time')
def get_time():
    # Your code here

Need a hint?

Use a simple dictionary cache = {} and set cache_timeout = 10.

3

Implement caching logic in route

Inside get_time, import time. Check if 'time' key exists in cache and if the cached timestamp is within cache_timeout. If valid, return the cached response. Otherwise, get the current time string, store it in cache['time'] with the current timestamp, and return it.

Flask

from flask import Flask
from datetime import datetime
import time

app = Flask(__name__)

cache = {}
cache_timeout = 10

@app.route('/time')
def get_time():
    # Your code here

Need a hint?

Use time.time() to get current timestamp. Store tuple of (response, timestamp) in cache.

4

Add app run block

Add the block if __name__ == '__main__': and inside it call app.run(debug=True) to run the Flask app in debug mode.

Flask

from flask import Flask
from datetime import datetime
import time

app = Flask(__name__)

cache = {}
cache_timeout = 10

@app.route('/time')
def get_time():
    now = time.time()
    if 'time' in cache and now - cache['time'][1] < cache_timeout:
        return cache['time'][0]
    current_time = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    cache['time'] = (current_time, now)
    return current_time

# Your code here

Need a hint?

This block runs the Flask app when you run the script directly.