Dynamic Module's service import

Question

I have a global dynamic module with a service named KafkaService, I want to use this service in my AuthenticationService, but NestJS seems can't inject the KafkaService

I have a KafkaModule which is a Dynamic and Global module

import { DynamicModule, Global, Module } from '@nestjs/common';
import { KafkaService } from './kafka.service';
import { KafkaConfig } from './kafka.types';

@Global()
@Module({})
export class KafkaModule {
  static register(kafkaConfig: KafkaConfig): DynamicModule {
    return {
      module: KafkaModule,
      global: true,
      providers: [
        {
          provide: KafkaService,
          useValue: new KafkaService(kafkaConfig),
        },
      ],
      exports: [KafkaService],
    };
  }
}

registered in AppModule

import { Module } from '@nestjs/common';
import { KafkaModule } from './common/kafka/kafka.module';
import { AuthenticationModule } from './modules/authentication.module';

@Module({
  imports: [
    KafkaModule.register({
      clientId: 'abc',
      brokers: ['localhost:9092'],
      groupId: 'def',
    }),
    AuthenticationModule,
  ],
})
export class AppModule {}

I want to use it in my service

import { Injectable } from '@nestjs/common';
import { SubscribeTo } from 'src/common/kafka/kafka.decorator';
import { KafkaService } from 'src/common/kafka/kafka.service';
import { Constant } from 'src/constant';

type LoginPayload = {
  username: string;
  password: string;
};

@Injectable()
export class AuthenticationService {
  constructor(private kafkaService: KafkaService) {}

  @SubscribeTo(Constant.TOPIC_LOGIN)
  async login(payload: LoginPayload) {
    console.log(this.kafkaService);
  }
}

UPDATE Apparently, the decorator is called before service injection

The decorator @SubscribeTo(Constant.TOPIC_LOGIN) will save the function in a variable that will be called later, and when this decorator is run the service is not yet injected to the class

So, I'm not using decorator to subscribe to the topic, and then modifying the Kafka module so that the consumer will not start at module initialization

Adding the error would be helpful here – Jay McDoniel Jan 04 '23 at 06:45 — Jay McDoniel, Jan 04 '23 at 06:45
No error, only `undefined` when I print `this.kafkaService` – Rahandi Noor Pasha Jan 04 '23 at 10:01 — Rahandi Noor Pasha, Jan 04 '23 at 10:01

score 0 · Answer 1 · answered Jan 04 '23 at 10:06

Apparently, the decorator is called before service injection

The decorator @SubscribeTo(Constant.TOPIC_LOGIN) will save the function in a variable that will be called later, and when this decorator is run the service is not yet injected to the class

So, I'm not using decorator to subscribe to the topic, and then modifying the Kafka module so that the consumer will not start at module initialization

Dynamic Module's service import

1 Answers1