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How to Add The Inbox Pattern To a NestJS Microservice

1. Enable the modules in AppModule​

./src/AppModule.ts
import { NestMicroserviceInboxModule } from '@tsm/nest/microservice-inbox';

@Module({})
export class AppModule extends BaseAppModule {
  public static imports(config: FrameworkModuleOptions<AppConfig>): (Type<object> | DynamicModule)[] {
    return [
      // infra
      // ...
      NestMicroserviceInboxModule,
    ];
  }

  // ...
}

2. Include the Inbox Pattern Entities in the TypeORM Config​

In order for typeorm to recognize the entities, you need to include the glob path to the inbox entities in the entities array in the DataSourceOptions file.

./src/infrastructure/TypeOrm/DataSourceOptions.ts
import { PostgresConnectionOptions } from 'typeorm/driver/postgres/PostgresConnectionOptions';
import { SnakeNamingStrategy } from 'typeorm-naming-strategies';

export const options: Partial<PostgresConnectionOptions> = {
  // ...
  entities: [
    // ...
    `${__dirname}/../../../../../libs/nest/microservice-inbox/**/!(*.spec).{ts,js}`,
  ],
};

3. Add the Inbox Interceptor to the Microservice Module​

Import the NestMicroserviceInboxModule with any module that needs to use the inbox pattern.

./src/infrastructure/EventStream/EventStreamModule.ts
import { Module } from '@nestjs/common';
import { NestMicroserviceInboxModule } from '@tsm/nest/microservice-inbox';
import { MessageController } from './MessageController';

@Module({
  controllers: [MessageController],
  imports: [NestMicroserviceInboxModule],
})
export class EventStreamModule {}

4. Add the Interceptors to the Module's Message Controllers​

Within the module that has imported NestMicroserviceInboxModule, add the InboxInterceptor to the message controllers using the @UseInterceptors decorator.

./src/infrastructure/EventStream/MessageController.ts
import { Controller, UseInterceptors } from '@nestjs/common';
import { EventPattern, Payload } from '@nestjs/microservices';
import { InboxInterceptor } from '@tsm/nest/microservice-inbox';

@Controller()
export class MessageController {
  @EventPattern(`DomainEvent.PatternOne`)
  @UseInterceptors(InboxInterceptor)
  public async handle(@Payload() event: PatternOne): Promise<void> {
    // ...
  }

  @EventPattern(`DomainEvent.PatternTwo`)
  @UseInterceptors(InboxInterceptor)
  public async handleAnother(@Payload() event: PatternTwo): Promise<void> {
    // ...
  }
}