Nestjs Provider

nodejs

字数统计: 204阅读时长: 1 min

 2023/08/31 

基础使用

// cat.service.ts

import { Injectable } from '@nestjs/common';
import { Cat } from './interfaces/cat.interface';

@Injectable()
export class CatsService {
  private readonly cats: Cat[] = [];

  findAll(): Cat[] {
    return this.cats;
  }
}

// App.module.ts

@Module({
	controllers: [CatController],
	providers: [CatService]
})
export class AppModule {
  
}

Value Provider

用于替换 class 的对象。可用于 mock。

import { CatsService } from './cats.service';

const mockCatsService = {
  /* mock implementation
  ...
  */
};

@Module({
  imports: [CatsModule],
  providers: [
    {
      provide: CatsService,
      useValue: mockCatsService,
    },
  ],
})
export class AppModule {}

Non-class-based provider tokens

用于传递参数和配置。

import { connection } from './connection';

@Module({
  providers: [
    {
      provide: 'CONNECTION',
      useValue: connection,
    },
  ],
})
export class AppModule {}

使用方式：

@Injectable()
export class CatsRepository {
  constructor(@Inject('CONNECTION') connection: Connection) {}
}

Class providers

用于通过参数的方式来传递类。

const configServiceProvider = {
  provide: ConfigService,
  useClass:
    process.env.NODE_ENV === 'development'
      ? DevelopmentConfigService
      : ProductionConfigService,
};

@Module({
  providers: [configServiceProvider],
})
export class AppModule {}