How to make FlowProducer as a Provider?

[play-nopparat]

can you someone help me fix the problem here? Nest shows the error

Error: Nest can't resolve dependencies of the RegisterService (?). Please make sure that the argument "BullFlowProducer_REGISTER_PRODUCER" at index [0] is available in the AdminModule context.

I have 2 modules here

• RegisterQueueModule
• AdminModule

In RegisterQueueModule, I register the flowProducer by

@Module({
  imports: [
    QueueBoardModule.register({
      queues: [REGISTER_CHILD, REGISTER_MERGE],
      flows: [REGISTER_PRODUCER],
    }),
  ],
  providers: [
    RegisterEventsListener,
    RegisterChildProcessor,
    RegisterMergeProcessor,
    RegisterService,
  ],
  exports: [],
})
export class RegisterQueueModule {}

Here is the QueueBoardModule.

import { BullMQAdapter } from '@bull-board/api/bullMQAdapter'
import { BullBoardModule } from '@bull-board/nestjs'
import { BullModule } from '@nestjs/bullmq'
import { DynamicModule, Module } from '@nestjs/common'
import { ConfigModule, ConfigService } from '@nestjs/config'
import {
  ConfigurableModuleClass,
  OPTIONS_TYPE,
} from './queue-board.module-defination'

@Module({})
export class QueueBoardModule extends ConfigurableModuleClass {
  static register(options: typeof OPTIONS_TYPE): DynamicModule {
    const bullBoardModules = options.queues.map((name) =>
      BullBoardModule.forFeature({
        name,
        adapter: BullMQAdapter,
      }),
    )

    const bullModules = options.queues.map((name) =>
      BullModule.registerQueueAsync({
        name,
        imports: [ConfigModule],
        inject: [ConfigService],
        useFactory: async (configService: ConfigService) => {
          const redisUrl = configService.get('REDIS_URL')
          const urlParts = new URL(redisUrl)
          return {
            connection: {
              host: urlParts.hostname,
              port: urlParts.port ? parseInt(urlParts.port, 10) : 6379,
            },
            defaultJobOptions: {
              removeOnComplete: 1000,
              removeOnFail: 5000,
              attempts: 3,
            },
          }
        },
      }),
    )

    const flowProducers = (options.flows || []).map((flow) =>
      BullModule.registerFlowProducerAsync({
        name: flow,
        imports: [ConfigModule],
        inject: [ConfigService],
        useFactory: async (configService: ConfigService) => {
          const redisUrl = configService.get('REDIS_URL')
          const urlParts = new URL(redisUrl)
          return {
            connection: {
              host: urlParts.hostname,
              port: urlParts.port ? parseInt(urlParts.port, 10) : 6379,
            },
          }
        },
      }),
    )

    return {
      ...super.register(options),
      imports: [...bullModules, ...bullBoardModules, ...flowProducers],
      exports: [...bullModules, ...flowProducers],
    }
  }
}

In the RegisterService class, I inject the flowProducer

constructor(
    @InjectRegisterProducer() private readonly registerFlow: FlowProducer,
  ) {
    super()
  }

In custom decorator.

export const InjectRegisterProducer = () =>
  InjectFlowProducer(REGISTER_PRODUCER)

In the AdminModule,

@Module({
  imports: [
    CqrsModule
    RegisterQueueModule,
  ],
  controllers: [AdminController],
  providers: [
    RegisterService,
  ],
})
export class AdminModule {}

I found a solution but it seems not to be the right solution by importing the same flow again in the AdminModule, and the error is gone.

@Module({
  imports: [
    QueueBoardModule.register({
          queues: [],
          flows: [REGISTER_PRODUCER],
      }),
    CqrsModule
    RegisterQueueModule,
  ],

Does anyone know the issue here, could you help me fix it? thank you.

[manast]

I am not familiar with Nest but this is what ChatGPT had to say about it:

The error you're encountering with NestJS and the Bull Queue indicates a common issue with dependency injection and module scoping within the NestJS framework. The error message:

Error: Nest can't resolve dependencies of the RegisterService (?). Please make sure that the argument "BullFlowProducer_REGISTER_PRODUCER" at index [0] is available in the AdminModule context.

suggests that the RegisterService, which depends on the BullFlowProducer_REGISTER_PRODUCER (your custom provider), cannot be resolved within the AdminModule because the BullFlowProducer_REGISTER_PRODUCER is not available in the module's context where RegisterService is declared.

Here's a step-by-step guide to address this issue:

1. Ensure Proper Exports in RegisterQueueModule

First, ensure that the RegisterQueueModule exports all providers that are supposed to be used in other modules, including the RegisterService and any custom providers or tokens like your BullFlowProducer_REGISTER_PRODUCER.

@Module({
  imports: [
    // Your existing imports
  ],
  providers: [
    // Your existing providers
    RegisterService,
    // Any other service that needs to be injected elsewhere
  ],
  exports: [
    RegisterService,
    // Ensure to export the provider or token that represents your flow producer
    // This might require you to explicitly export the flow producer
  ],
})
export class RegisterQueueModule {}

2. Custom Provider Export

Make sure that your custom provider (BullFlowProducer_REGISTER_PRODUCER) is correctly exported from the RegisterQueueModule. If this provider is defined by using BullModule.registerFlowProducerAsync, you need to ensure that the resulting provider is included in the exports array of the module.

However, BullModule.registerFlowProducerAsync does not automatically make the provider globally available. You need to either:

• Make the provider global (not always recommended due to potential conflicts).
• Explicitly export the provider by adding it to the exports array of the module.

3. Use Global Modules (If Appropriate)

If the BullFlowProducer_REGISTER_PRODUCER is something that will be reused across many modules, consider making the module that provides it a global module. You can make a module global by adding @Global() decorator to the module definition. This makes its exports available throughout the application without needing to import the module everywhere.

@Global()
@Module({
  // Module contents
})
export class YourModuleProvidingFlowProducer {}

4. Verify Module Imports

Ensure that the AdminModule imports the RegisterQueueModule. You've already done this, but it's good to reiterate the importance of this step for resolving providers.

5. Consider Simplifying Dependency Injection

If the issue persists, consider revising how the BullFlowProducer_REGISTER_PRODUCER is provided and injected. The custom decorator and injection token should be correctly defined and consistent across the application. Ensure that InjectRegisterProducer correctly abstracts the injection token or provider name used to register the flow producer.

Conclusion

The solution you found works because importing QueueBoardModule.register with the flows array including REGISTER_PRODUCER in the AdminModule directly makes the BullFlowProducer_REGISTER_PRODUCER available in the AdminModule context. However, this might not be the cleanest solution if it leads to duplication or circular dependencies.

Ideally, you should ensure that all necessary providers are exported by the modules that declare them and are imported by any module that needs them. This might require adjusting the exports of RegisterQueueModule or rethinking how the flow producers are made available across modules.