Exceptions in microservices on nestjs

Question

I have a microservice application, an api gateway and a service. RabbitMQ is used as a message broker. I realized that in the service you need to use RpcException with message and statusCode instead of HttpException. But I ran into difficulty when using ValidationPipe when validating data in DTO, I get 500 statusCode from api gateway. Because under the hood it throws a BadRequestException. I honestly do not understand what I need to do to convert this exception to the rpc format, or maybe I need to do something else. Perhaps some kind of exceptionFilter is needed, but I do not understand how to do it.

api gateway

@Controller()
export class ApiGateway {
constructor(
    @Inject('AUTH_SERVICE') private authService: ClientProxy,
  ) {}
@Post('auth/register')
  async register(
    @Body('email') email: string,
    @Body('password') password: string | number,
  ) {
    return this.authService.send({ cmd: 'register' }, { email, password });
  }
}

main.ts auth

async function bootstrap() {
  const app = await NestFactory.create(AuthModule);

  const configService = app.get(ConfigService);
  const rmqService = app.get(RmqService);
  const queue = configService.get('RABBITMQ_AUTH_QUEUE');
  app.connectMicroservice(rmqService.getOptions(queue));
  await app.startAllMicroservices();
}
bootstrap();

auth.controller

@Controller()
export class AuthController {
constructor(
    private readonly authService: AuthService,
    private readonly rmqService: RmqService,
  ) {}
@MessagePattern({ cmd: 'register' })
  async register(@Ctx() ctx: RmqContext, @Payload() newUser: UserDto) {
    this.rmqService.acknowledgeMessage(ctx);

    return this.authService.register(newUser);
  }
}

UserDto

@UsePipes(new ValidationPipe({ whitelist: true }))
export class UserDto {
  @IsEmail()
  email: string;

  @IsString()
  @IsNotEmpty()
  password: string;
}

Answer 1

I managed to override HttpException with RpcException. I also redefined the form in which I will receive validation error messages, maybe it will be useful to someone

export const VALIDATION_PIPE_OPTIONS = {
  transform: true,
  whitelist: true,
  exceptionFactory: (errors) => {
    return new RpcException({
      message: validationErrorsConversion(errors),
      statusCode: 400,
    });
  },
};

export function validationErrorsConversion(arr) {
  const result = [];

  arr.forEach((obj) => {
    const { property, constraints } = obj;
    const values = Object.keys(constraints).map(
      (key) => VALIDATION_ERRORS_CONST[key] || constraints[key],
    );

    result.push({
      [property]: values,
    });
  });

  return result;
}

export const VALIDATION_ERRORS_CONST = {
  isEmail: 'Is not email',
  isString: 'It should be a string',
};