Caching

Caching is a great and simple technique that helps improve your app's performance. It acts as a temporary data store providing high performance data access.

Installation

First install required packages:

$ npm install @nestjs/cache-manager cache-manager

warning Warning cache-manager version 4 uses seconds for TTL (Time-To-Live). The current version of cache-manager (v5) has switched to using milliseconds instead. NestJS doesn't convert the value, and simply forwards the ttl you provide to the library. In other words:

If using cache-manager v4, provide ttl in seconds

If using cache-manager v5, provide ttl in milliseconds

Documentation is referring to seconds, since NestJS was released targeting version 4 of cache-manager.

In-memory cache

Nest provides a unified API for various cache storage providers. The built-in one is an in-memory data store. However, you can easily switch to a more comprehensive solution, like Redis.

In order to enable caching, import the CacheModule and call its register() method.

import { Module } from '@nestjs/common';
import { CacheModule } from '@nestjs/cache-manager';
import { AppController } from './app.controller';

@Module({
  imports: [CacheModule.register()],
  controllers: [AppController],
})
export class AppModule {}

Interacting with the Cache store

To interact with the cache manager instance, inject it to your class using the CACHE_MANAGER token, as follows:

constructor(@Inject(CACHE_MANAGER) private cacheManager: Cache) {}

info Hint The Cache class is imported from the cache-manager, while CACHE_MANAGER token from the @nestjs/cache-manager package.

The get method on the Cache instance (from the cache-manager package) is used to retrieve items from the cache. If the item does not exist in the cache, null will be returned.

const value = await this.cacheManager.get('key');

To add an item to the cache, use the set method:

await this.cacheManager.set('key', 'value');

warning Note The in-memory cache storage can only store values of types that are supported by the structured clone algorithm.

The default expiration time of the cache is 5 seconds.

You can manually specify a TTL (expiration time in seconds) for this specific key, as follows:

await this.cacheManager.set('key', 'value', 1000);

To disable expiration of the cache, set the ttl configuration property to 0:

await this.cacheManager.set('key', 'value', 0);

To remove an item from the cache, use the del method:

await this.cacheManager.del('key');

To clear the entire cache, use the reset method:

await this.cacheManager.reset();

Auto-caching responses

warning Warning In GraphQL applications, interceptors are executed separately for each field resolver. Thus, CacheModule (which uses interceptors to cache responses) will not work properly.

To enable auto-caching responses, just tie the CacheInterceptor where you want to cache data.

@Controller()
@UseInterceptors(CacheInterceptor)
export class AppController {
  @Get()
  findAll(): string[] {
    return [];
  }
}

warningWarning Only GET endpoints are cached. Also, HTTP server routes that inject the native response object (@Res()) cannot use the Cache Interceptor. See response mapping for more details.

To reduce the amount of required boilerplate, you can bind CacheInterceptor to all endpoints globally:

import { Module } from '@nestjs/common';
import { CacheModule, CacheInterceptor } from '@nestjs/cache-manager';
import { AppController } from './app.controller';
import { APP_INTERCEPTOR } from '@nestjs/core';

@Module({
  imports: [CacheModule.register()],
  controllers: [AppController],
  providers: [
    {
      provide: APP_INTERCEPTOR,
      useClass: CacheInterceptor,
    },
  ],
})
export class AppModule {}

Customize caching

All cached data has its own expiration time (TTL). To customize default values, pass the options object to the register() method.

CacheModule.register({
  ttl: 5, // seconds
  max: 10, // maximum number of items in cache
});

Use module globally

When you want to use CacheModule in other modules, you'll need to import it (as is standard with any Nest module). Alternatively, declare it as a global module by setting the options object's isGlobal property to true, as shown below. In that case, you will not need to import CacheModule in other modules once it's been loaded in the root module (e.g., AppModule).

CacheModule.register({
  isGlobal: true,
});

Global cache overrides

While global cache is enabled, cache entries are stored under a CacheKey that is auto-generated based on the route path. You may override certain cache settings (@CacheKey() and @CacheTTL()) on a per-method basis, allowing customized caching strategies for individual controller methods. This may be most relevant while using different cache stores.

You can apply the @CacheTTL() decorator on a per-controller basis to set a caching TTL for the entire controller. In situations where both controller-level and method-level cache TTL settings are defined, the cache TTL settings specified at the method level will take priority over the ones set at the controller level.

@Controller()
@CacheTTL(50)
export class AppController {
  @CacheKey('custom_key')
  @CacheTTL(20)
  findAll(): string[] {
    return [];
  }
}

info Hint The @CacheKey() and @CacheTTL() decorators are imported from the @nestjs/cache-manager package.

The @CacheKey() decorator may be used with or without a corresponding @CacheTTL() decorator and vice versa. One may choose to override only the @CacheKey() or only the @CacheTTL(). Settings that are not overridden with a decorator will use the default values as registered globally (see Customize caching).

WebSockets and Microservices

You can also apply the CacheInterceptor to WebSocket subscribers as well as Microservice's patterns (regardless of the transport method that is being used).

@@filename()
@CacheKey('events')
@UseInterceptors(CacheInterceptor)
@SubscribeMessage('events')
handleEvent(client: Client, data: string[]): Observable<string[]> {
  return [];
}
@@switch
@CacheKey('events')
@UseInterceptors(CacheInterceptor)
@SubscribeMessage('events')
handleEvent(client, data) {
  return [];
}

However, the additional @CacheKey() decorator is required in order to specify a key used to subsequently store and retrieve cached data. Also, please note that you shouldn't cache everything. Actions which perform some business operations rather than simply querying the data should never be cached.

Additionally, you may specify a cache expiration time (TTL) by using the @CacheTTL() decorator, which will override the global default TTL value.

@@filename()
@CacheTTL(10)
@UseInterceptors(CacheInterceptor)
@SubscribeMessage('events')
handleEvent(client: Client, data: string[]): Observable<string[]> {
  return [];
}
@@switch
@CacheTTL(10)
@UseInterceptors(CacheInterceptor)
@SubscribeMessage('events')
handleEvent(client, data) {
  return [];
}

info Hint The @CacheTTL() decorator may be used with or without a corresponding @CacheKey() decorator.

Adjust tracking

By default, Nest uses the request URL (in an HTTP app) or cache key (in websockets and microservices apps, set through the @CacheKey() decorator) to associate cache records with your endpoints. Nevertheless, sometimes you might want to set up tracking based on different factors, for example, using HTTP headers (e.g. Authorization to properly identify profile endpoints).

In order to accomplish that, create a subclass of CacheInterceptor and override the trackBy() method.

@Injectable()
class HttpCacheInterceptor extends CacheInterceptor {
  trackBy(context: ExecutionContext): string | undefined {
    return 'key';
  }
}

Different stores

This service takes advantage of cache-manager under the hood. The cache-manager package supports a wide-range of useful stores, for example, Redis store. A full list of supported stores is available here. To set up the Redis store, simply pass the package together with corresponding options to the register() method.

import type { RedisClientOptions } from 'redis';
import * as redisStore from 'cache-manager-redis-store';
import { Module } from '@nestjs/common';
import { CacheModule } from '@nestjs/cache-manager';
import { AppController } from './app.controller';

@Module({
  imports: [
    CacheModule.register<RedisClientOptions>({
      store: redisStore,

      // Store-specific configuration:
      host: 'localhost',
      port: 6379,
    }),
  ],
  controllers: [AppController],
})
export class AppModule {}

warningWarning cache-manager-redis-store does not support redis v4. In order for the ClientOpts interface to exist and work correctly you need to install the latest redis 3.x.x major release. See this issue to track the progress of this upgrade.

Async configuration

You may want to asynchronously pass in module options instead of passing them statically at compile time. In this case, use the registerAsync() method, which provides several ways to deal with async configuration.

One approach is to use a factory function:

CacheModule.registerAsync({
  useFactory: () => ({
    ttl: 5,
  }),
});

Our factory behaves like all other asynchronous module factories (it can be async and is able to inject dependencies through inject).

CacheModule.registerAsync({
  imports: [ConfigModule],
  useFactory: async (configService: ConfigService) => ({
    ttl: configService.get('CACHE_TTL'),
  }),
  inject: [ConfigService],
});

Alternatively, you can use the useClass method:

CacheModule.registerAsync({
  useClass: CacheConfigService,
});

The above construction will instantiate CacheConfigService inside CacheModule and will use it to get the options object. The CacheConfigService has to implement the CacheOptionsFactory interface in order to provide the configuration options:

@Injectable()
class CacheConfigService implements CacheOptionsFactory {
  createCacheOptions(): CacheModuleOptions {
    return {
      ttl: 5,
    };
  }
}

If you wish to use an existing configuration provider imported from a different module, use the useExisting syntax:

CacheModule.registerAsync({
  imports: [ConfigModule],
  useExisting: ConfigService,
});

This works the same as useClass with one critical difference - CacheModule will lookup imported modules to reuse any already-created ConfigService, instead of instantiating its own.

info Hint CacheModule#register and CacheModule#registerAsync and CacheOptionsFactory has an optional generic (type argument) to narrow down store-specific configuration options, making it type safe.

Example

A working example is available here.

Installation​

In-memory cache​

Interacting with the Cache store​

Auto-caching responses​

Customize caching​

Use module globally​

Global cache overrides​

WebSockets and Microservices​

Adjust tracking​

Different stores​

Async configuration​

Example​