TTL configuration in NestJS - Mini Project: Build & Apply

TTL Configuration in NestJS Cache Module

📖 Scenario: You are building a NestJS application that caches user data to improve performance. You want to configure the cache so that cached data expires automatically after a certain time (TTL - Time To Live).

🎯 Goal: Configure the NestJS CacheModule with a TTL of 5 seconds and create a service that caches and retrieves user data.

📋 What You'll Learn

Import CacheModule with TTL configuration set to 5 seconds

Create a service called UserCacheService

Use cacheManager to set and get cached user data

Ensure cached data expires after 5 seconds automatically

💡 Why This Matters

🌍 Real World

Caching user data with TTL helps improve app performance by reducing repeated database calls and automatically cleaning up stale data.

💼 Career

Understanding TTL configuration and cache management is essential for backend developers working with NestJS to build scalable and efficient applications.

1

Import CacheModule with TTL configuration

In your AppModule, import CacheModule from @nestjs/cache-manager and configure it with ttl: 5 inside CacheModule.register().

NestJS

import { Module } from '@nestjs/common';
import { CacheModule } from '@nestjs/cache-manager';

@Module({
  imports: [
    // Register CacheModule with TTL 5 seconds
  ],
})
export class AppModule {}

Need a hint?

Use CacheModule.register({ ttl: 5 }) inside the imports array of @Module.

2

Create UserCacheService with cacheManager injection

Create a service class called UserCacheService. Inject CACHE_MANAGER using @Inject and assign it to a private variable called cacheManager.

NestJS

import { Injectable, Inject, CACHE_MANAGER } from '@nestjs/common';
import { Cache } from 'cache-manager';

@Injectable()
export class UserCacheService {
  constructor(
    // Inject CACHE_MANAGER here
  ) {}
}

Need a hint?

Use @Inject(CACHE_MANAGER) in the constructor to get the cache manager instance.

3

Add methods to set and get cached user data

Inside UserCacheService, add an async method cacheUserData that takes userId and data and uses this.cacheManager.set() to cache the data. Also add an async method getUserData that takes userId and returns cached data using this.cacheManager.get().

NestJS

import { Injectable, Inject, CACHE_MANAGER } from '@nestjs/common';
import { Cache } from 'cache-manager';

@Injectable()
export class UserCacheService {
  constructor(
    @Inject(CACHE_MANAGER) private cacheManager: Cache,
  ) {}

  // Add async cacheUserData(userId: string, data: any) method
  // Add async getUserData(userId: string) method
}

Need a hint?

Use this.cacheManager.set(key, value) to store and this.cacheManager.get(key) to retrieve cached data.

4

Register UserCacheService in AppModule providers

Add UserCacheService to the providers array in AppModule so it can be injected and used in the application.

NestJS

import { Module } from '@nestjs/common';
import { CacheModule } from '@nestjs/cache-manager';
import { UserCacheService } from './user-cache.service';

@Module({
  imports: [
    CacheModule.register({ ttl: 5 }),
  ],
  // Add UserCacheService to providers array
})
export class AppModule {}

// UserCacheService code remains unchanged

Need a hint?

Add UserCacheService inside the providers array of @Module.