I'm building a NestJS app with the @golevelup/nestjs-rabbitmq library to publish messages to a rabbitmq exchange.

我正在使用@goevelup/nestjs-rabbitmq库构建一个NestJS应用程序，以便将消息发布到rabbitmq交易所。

I'm importing and configuring the RabbitMQ module in the AppModule (this part appears to work correctly).

我正在AppModule中导入和配置RabbitMQ模块(这部分似乎工作正常)。

I've created a module called MessagingModule and a service MessagingService. However, when I attempt to create the MessagingService and inject the AmqpConnection object into the constructor, there is an error.

我已经创建了一个名为MessagingModule的模块和一个服务MessagingService。但是，当我尝试创建MessagingService并将AmqpConnection对象注入构造函数时，出现错误。

Error:

错误：

error:  Nest can't resolve dependencies of the RabbitMQModule (DiscoveryService, ExternalContextCreator, ?, AmqpConnectionManager). Please make sure that the argument RabbitRpcParamsFactory at index [2] is available in the RabbitMQModule context.

Potential solutions:
- Is RabbitMQModule a valid NestJS module?
- If RabbitRpcParamsFactory is a provider, is it part of the current RabbitMQModule?
- If RabbitRpcParamsFactory is exported from a separate @Module, is that module imported within RabbitMQModule?

App module

应用程序模块

import { ConfigModule } from '@nestjs/config';
import { configuration } from './config/configuration';
import { MessagingModule } from './messaging/messaging.module';
import { RabbitMQModule } from '@golevelup/nestjs-rabbitmq';
import { ConfigService } from '@nestjs/config';

@Module({
  imports: [
    ConfigModule.forRoot({
      isGlobal: true,
      cache: true,
      load: [configuration],
      validationSchema,
      validationOptions: {
        allowUnkown: false,
        abortEarly: true,
      },
    }),
    RabbitMQModule.forRootAsync(RabbitMQModule, {
      imports: [ConfigModule],
      inject: [ConfigService],
      useFactory: async (configService: ConfigService) => ({
        exchanges: [
          {
            name: configService.get<string>('RABBITMQ_EXCHANGE'),
            type: configService.get<string>('RABBITMQ_EXCHANGE_TYPE'),
          },
        ],
        uri: configService.get<string>('RABBITMQ_URL'),
        channels: {
          'channel-1': {
            prefetchCount: 15,
            default: true,
          },
          'channel-2': {
            prefetchCount: 2,
          },
        },
        connectionInitOptions: { wait: false },
        enableControllerDiscovery: true,
      }),
    }),
    MessagingModule,
  ],
  controllers: [],
  providers: [],
})
export class AppModule {}

Messaging module

消息模块

import { RabbitMQModule } from '@golevelup/nestjs-rabbitmq';
import { Module } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { MessagingService } from './messaging.service';
import { MessagingController } from './messaging.controller';

@Module({
  
  imports: [
    RabbitMQModule,
    MessagingModule,
  ],
  providers: [ConfigService, MessagingService],
  controllers: [MessagingController],
  exports: [MessagingService],
})
export class MessagingModule {}

Messaging Service

消息传送服务

import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { AmqpConnection } from '@golevelup/nestjs-rabbitmq';

@Injectable()
export class MessagingService {
  constructor(private readonly amqpConnection: AmqpConnection) {}

  // Publish the event to the exchange
  public async publish<T>(exchange: string, event: T): Promise<void> {
    await this.amqpConnection.publish(exchange, '', event);
  }

}

Every time you want to use the RabbitMQModule, you need to use the forRoot/forRootAsync method to ensure all of the providers the module needs are set up. If you want to only need to call this once, you can set up a wrapper module for it like so:

每次你想使用RabbitMQModule时，你都需要使用forRoot/forRootAsync方法来确保模块所需的所有提供程序都已设置。如果你想只调用一次，你可以为它设置一个包装器模块，如下所示：

@Module({
  imports: [
    RabbitMQModule.forRootAsync(RabbitMQModule, {
      imports: [ConfigModule],
      inject: [ConfigService],
      useFactory: async (configService: ConfigService) => ({
        exchanges: [
          {
            name: configService.get<string>('RABBITMQ_EXCHANGE'),
            type: configService.get<string>('RABBITMQ_EXCHANGE_TYPE'),
          },
        ],
        uri: configService.get<string>('RABBITMQ_URL'),
        channels: {
          'channel-1': {
            prefetchCount: 15,
            default: true,
          },
          'channel-2': {
            prefetchCount: 2,
          },
        },
        connectionInitOptions: { wait: false },
        enableControllerDiscovery: true,
      }),
    }),
  ],
  exports: [RabbitMQModule],
})
export class RabbitModule {}

Now you can add the RabbitModule instead of RabbitMQModule and you'll get the same RabbitMQModule that's pre-configured each time.

现在，您可以添加RabbitModule而不是RabbitMQModule，您将得到每次都预先配置的RabbitMQModule。