Real-time notification pattern in Redis - Mini Project: Build & Apply

Real-time Notification Pattern with Redis

📖 Scenario: You are building a simple real-time notification system for a social media app. Users receive notifications when someone likes their post.

🎯 Goal: Create a Redis data structure to store notifications, configure a threshold for unread notifications, implement the logic to add new notifications, and finalize the setup to mark notifications as read.

📋 What You'll Learn

Create a Redis list called notifications:user123 with three initial notifications

Add a variable max_unread set to 5 to limit unread notifications

Write a Redis command to add a new notification to notifications:user123

Write a Redis command to trim the list to keep only the latest max_unread notifications

💡 Why This Matters

🌍 Real World

Real-time notifications are essential in social media apps, messaging platforms, and online marketplaces to keep users engaged and informed instantly.

💼 Career

Understanding how to use Redis lists and commands like LPUSH and LTRIM is valuable for backend developers working on scalable, real-time systems.

1

DATA SETUP: Create initial notifications list

Create a Redis list called notifications:user123 and add these three notifications exactly: 'Like from Alice', 'Like from Bob', 'Like from Charlie' using LPUSH commands.

Redis

# Use LPUSH to add 'Like from Alice', 'Like from Bob', and 'Like from Charlie' to notifications:user123
# Your code here

Need a hint?

Use LPUSH to add items to the Redis list notifications:user123. Add each notification as a separate command.

2

CONFIGURATION: Set maximum unread notifications

Create a variable called max_unread and set it to 5 to limit the number of unread notifications stored.

Redis

LPUSH notifications:user123 'Like from Alice'
LPUSH notifications:user123 'Like from Bob'
LPUSH notifications:user123 'Like from Charlie'

# Set max_unread to 5
# Your code here

Need a hint?

Assign the number 5 to a variable named max_unread to represent the maximum unread notifications.

3

CORE LOGIC: Add a new notification

Use LPUSH to add a new notification 'Like from Dave' to the Redis list notifications:user123.

Redis

LPUSH notifications:user123 'Like from Alice'
LPUSH notifications:user123 'Like from Bob'
LPUSH notifications:user123 'Like from Charlie'

max_unread=5

# Add 'Like from Dave' notification
# Your code here

Need a hint?

Use LPUSH to add the new notification 'Like from Dave' to the list notifications:user123.

4

COMPLETION: Trim the notifications list

Use the LTRIM command to keep only the latest max_unread notifications in the list notifications:user123. Use the range 0 to max_unread - 1.

Redis

LPUSH notifications:user123 'Like from Alice'
LPUSH notifications:user123 'Like from Bob'
LPUSH notifications:user123 'Like from Charlie'

max_unread=5

LPUSH notifications:user123 'Like from Dave'

# Trim the list to max_unread notifications
# Your code here

Need a hint?

Use LTRIM notifications:user123 0 4 to keep only the first 5 notifications (index 0 to 4).