在nestjs提供cache http request by url/microservice message by key的module，cache module也是第三方套件cache manager的wrapper。

基本設定

先安裝cache-manager套件，提供簡易in-memory cache功能

yarn add cache-manager

要啟用cache先import module

假設要cache get Users

修改src/user/user.module.ts

@Module({
    imports: [
        ...
        CacheModule.register(),
    ],
    controllers: [
       ...controllersForUser,
    ],
    providers: [
        ...servicesForUser,
    ],
    exports: [
        ...servicesForUser,
    ]
})
export class UserModule {}

再到users.controller.ts對應的方法套用CacheInterceptor

@Controller('users')
export class UsersController {
    constructor(
        private usersService: UsersService,
    ){}

  @ApiOkResponse({description:'Return Users Array'})
  @MessagePattern({accountData:'users'})
  @Get()
  @UseInterceptors(CacheInterceptor) // 套用Cache Interceptor
  userList(){
    return this.usersService.getUsers();
  }
  
  ...
}

如果要cache microservice TCP request的話，改用@CacheKey()，傳入@MessagePattern中的key，如account data

  @ApiOkResponse({description:'Return Users Array'})
  @CacheKey('accountData')
  @MessagePattern({accountData:'users'})
  @Get()
  @UseInterceptors(CacheInterceptor)
  userList(){
    return this.usersService.getUsers();
  }

使用Redis As Cache Store

要改用redis也相當容易，cache-manager有cache-manager-redis-store套件

yarn add cache-manager-redis-store

在Cache Module Register時傳入設定物件

import * as redisStore from 'cache-manager-redis-store';
@Module({
    imports: [
        ...
        CacheModule.register({
            store: redisStore, // import from cache-manager-redis-store
            host: '192.168.99.100', // redis server host ip
            post: 6379, // port
            ttl: 5, // 5秒有效
            max: 50, // 50個items
        }),
    ],
   ...
})
export class UserModule {}

當然如果沒有設定對，沒有找到redis server是會app crash的