Caching with Redis

import { createClient } from 'redis';

const redis = createClient({ url: process.env.REDIS_URL });
await redis.connect();

// Basic key-value operations
await redis.set('key', 'value');
await redis.set('key', 'value', { EX: 3600 }); // expire in 1 hour
const value = await redis.get('key');
await redis.del('key');

// Working with objects (serialize with JSON)
await redis.set('user:42', JSON.stringify(userObject));
const user = JSON.parse(await redis.get('user:42') ?? 'null');

// Increment (for rate limiting, counts)
await redis.incr('api:hits');
await redis.expire('api:hits', 60); // reset every minute

// Lists (for queues)
await redis.lPush('job-queue', JSON.stringify(job));
const job = await redis.rPop('job-queue');

// Hash (efficient for partial updates)
await redis.hSet('product:42', { name: 'Laptop', price: 45000 });
const name = await redis.hGet('product:42', 'name');

import { createClient } from 'redis';

const redis = createClient({ url: process.env.REDIS_URL });
await redis.connect();

// Cache-Aside Pattern: Check cache first, then DB
async function getProduct(productId: string) {
  const cacheKey = `product:${productId}`;

  // 1. Check cache
  const cached = await redis.get(cacheKey);
  if (cached) {
    console.log('Cache HIT for', productId);
    return JSON.parse(cached);
  }

  // 2. Cache miss — fetch from DB
  console.log('Cache MISS for', productId);
  const product = await prisma.product.findUnique({
    where: { id: productId },
    include: { category: true, images: true },
  });

  if (!product) return null;

  // 3. Store in cache for 5 minutes
  await redis.set(cacheKey, JSON.stringify(product), { EX: 300 });
  return product;
}

// Rate limiting with Redis sliding window
async function checkRateLimit(userId: string, limit = 100, window = 60): Promise<boolean> {
  const key = `rate:${userId}`;
  const current = await redis.incr(key);
  if (current === 1) await redis.expire(key, window); // set expiry on first request
  return current <= limit;
}

// Invalidate cache when product is updated
async function updateProduct(id: string, data: Partial<Product>) {
  const product = await prisma.product.update({ where: { id }, data });
  await redis.del(`product:${id}`); // invalidate cache
  return product;
}