Nestjs:从带有后缀钩子的模型/实体调用服务函数

Question

在NestJS中，我必须在entity/model中使用模块服务将数据填充到elastic-search索引中。填充弹性搜索索引逻辑是用Job.service.ts编写的。

我想从模型中出现的后缀钩子中调用来自Job.service.ts的Job.service.ts方法。

这是Job.ts模型/实体的代码-

import { Table, Model, Column, AutoIncrement, PrimaryKey } from "sequelize-typescript";

@Table({ schema: "job", tableName: "job" })
export class Job extends Model<Job> {
  @AutoIncrement
  @PrimaryKey
  @Column
  id: number;

  @Column
  title: string;

  @AfterCreate
  static async jobAfterCreate(instance, options) {
    // <--- need to call job service onCreate method here
  }

  @AfterUpdate
  static async jobAfterUpdate() {}

  @AfterDestroy
  static async jobAfterDestroy() {}
}

这是Job.service.ts的代码-

//imports not added
@Injectable()
export class JobService {
  constructor(
    @Inject("SEQUELIZE")
    private readonly sequelizeInstance: Sequelize,
    @Inject(forwardRef(() => ElasticsearchService))
    private readonly elasticsearchService: ElasticsearchService,
    @InjectModel(Job)
    private jobModel: typeof Job
  ) {}

  // here will write logic for updating elastic search index
  async onCreate(instance, options){
    console.log("ON CREATE INSTANCE:", instance);
    console.log("ON CREATE OPTIONS:", options);
  }
  async onDestroy(instance, options){
    console.log("ON DESTROY INSTANCE:", instance);
    console.log("ON DESTROY OPTIONS:", options);
  }
}

我尝试将服务注入Job模型，但没有奏效。而且我不能直接在模型中编写弹性搜索逻辑，因为我需要ElasticsearchService。

Answer 1

解决方案是覆盖提供程序。

向模型中注入信息的主要方法是重写注入行为。

首先，您需要添加引用模型中服务的静态属性。

我将以事件发射器为例。

你的模型类

import {Model, Table, Column, AfterCreate} from "sequelize-typescript"; 
import { EventEmitter2 } from "@nestjs/event-emitter";

@Table()
export class SomeModel extends <SomeModel> {

  // this would be your referencing
  public static EventEmitter: EventEmitter2;

  @Column
  public someColumn: string;


  @AfterCreate
  public static triggerSomeEvent(instance: SomeModel) {
    SomeModel.EventEmitter.emit('YourEvent', instance);
  } 
}

要使用模型的模块

现在，我们正在重写默认的注入过程。

import { EntitiesMetadataStorage } from '@nestjs/sequelize/dist/entities-metadata.storage';
import {
  getConnectionToken,
  getModelToken,
  SequelizeModule,
} from '@nestjs/sequelize';
import { EventEmitter2 } from '@nestjs/event-emitter';

// The provider override
const modelInjector: Provider = {
  provide: getModelToken(AccountabilityPartnerModel, DEFAULT_CONNECTION_NAME),
  useFactory: (connection: Sequelize, eventEmitter: EventEmitter2) => {
    SomeModel.EventEmitter = eventEmitter;
    if (!connection.repositoryMode) {
      return SomeModel;
    }
    return connection.getRepository(SomeModelas any);
  },
  inject: [getConnectionToken(DEFAULT_CONNECTION_NAME), EventEmitter2],
};

// Updating the meta information of sequelize-typescript package to handle connection injection in to the model overridden.

EntitiesMetadataStorage.addEntitiesByConnection(DEFAULT_CONNECTION_NAME, [
  SomeModel,
]);


// our custom module being used rather than the Sequelize.forFeature([SomeModel])
const someModelModule: DynamicModule = {
  module: SequelizeModule,
  providers: [modelInjector],
  exports: [modelInjector],
};


@Module({
  imports: [someModelModule],
  providers: [SomeService],
})
export class SomeModule {
}

像使用Sequlize.forFeature和InjectModel一样，将模型注入到服务中，如下所示。

@Injectable()
export class SomeService {
 constructor(@InjectModel(SomeModel) someModel: typeof SomeModel) {}

 public someFunction(data: any) {
   this.someModel.EventEmitter.emit('YourEvent', data);
 }
}