Named jobs in NestJS - Mini Project: Build & Apply

Named Jobs with NestJS Bull Queue

📖 Scenario: You are building a NestJS application that processes background tasks using Bull queues. You want to organize your jobs by giving each job a specific name. This helps you identify and manage different types of jobs easily.

🎯 Goal: Create a Bull queue in NestJS and add named jobs to it. Then, set up a processor that listens for jobs by their names and handles them accordingly.

📋 What You'll Learn

Create a Bull queue named emailQueue

Add a named job sendWelcomeEmail with data containing userId: 123

Add a named job sendPasswordReset with data containing userId: 456

Create a processor that listens for sendWelcomeEmail jobs and logs the userId

Create a processor that listens for sendPasswordReset jobs and logs the userId

💡 Why This Matters

🌍 Real World

Named jobs help organize background tasks like sending different types of emails or processing different workflows in a clear way.

💼 Career

Understanding named jobs in queues is important for backend developers working with task queues, microservices, and scalable applications.

1

Setup Bull queue in NestJS

Import BullModule in your module and register a queue named emailQueue using BullModule.registerQueue.

NestJS

import { Module } from '@nestjs/common';
import { BullModule } from '@nestjs/bull';

@Module({
  imports: [
    // Register the queue here
  ],
})
export class AppModule {}

Need a hint?

Use BullModule.registerQueue({ name: 'emailQueue' }) inside the imports array.

2

Add named jobs to the queue

Inject the emailQueue using @InjectQueue('emailQueue') in a service. Add two named jobs: sendWelcomeEmail with data { userId: 123 } and sendPasswordReset with data { userId: 456 } using emailQueue.add.

NestJS

import { Injectable } from '@nestjs/common';
import { InjectQueue } from '@nestjs/bull';
import { Queue } from 'bull';

@Injectable()
export class EmailService {
  constructor(@InjectQueue('emailQueue') private emailQueue: Queue) {}

  async addJobs() {
    // Add sendWelcomeEmail job
    // Add sendPasswordReset job
  }
}

Need a hint?

Use this.emailQueue.add('sendWelcomeEmail', { userId: 123 }) and similarly for sendPasswordReset.

3

Create processors for named jobs

Create a processor class decorated with @Processor('emailQueue'). Add two methods decorated with @Process('sendWelcomeEmail') and @Process('sendPasswordReset'). Each method receives a job and logs job.data.userId.

NestJS

import { Processor, Process } from '@nestjs/bull';
import { Job } from 'bull';

@Processor('emailQueue')
export class EmailProcessor {
  @Process('sendWelcomeEmail')
  async handleWelcomeEmail(job: Job) {
    // Log userId from job.data
  }

  @Process('sendPasswordReset')
  async handlePasswordReset(job: Job) {
    // Log userId from job.data
  }
}

Need a hint?

Use @Processor('emailQueue') on the class and @Process('sendWelcomeEmail') and @Process('sendPasswordReset') on methods.

4

Trigger job addition in application

In the EmailService, add a method called start that calls addJobs(). Then, in the AppModule, inject EmailService and call start() in the constructor to trigger job addition when the app starts.

NestJS

import { Module } from '@nestjs/common';
import { BullModule, Processor, Process } from '@nestjs/bull';
import { Injectable } from '@nestjs/common';
import { InjectQueue } from '@nestjs/bull';
import { Queue, Job } from 'bull';

@Injectable()
export class EmailService {
  constructor(@InjectQueue('emailQueue') private emailQueue: Queue) {}

  async addJobs() {
    await this.emailQueue.add('sendWelcomeEmail', { userId: 123 });
    await this.emailQueue.add('sendPasswordReset', { userId: 456 });
  }

  // Add start method here
}

@Processor('emailQueue')
export class EmailProcessor {
  @Process('sendWelcomeEmail')
  async handleWelcomeEmail(job: Job) {
    console.log(`Welcome email userId: ${job.data.userId}`);
  }

  @Process('sendPasswordReset')
  async handlePasswordReset(job: Job) {
    console.log(`Password reset userId: ${job.data.userId}`);
  }
}

@Module({
  imports: [
    BullModule.registerQueue({
      name: 'emailQueue',
    }),
  ],
  providers: [EmailService, EmailProcessor],
})
export class AppModule {
  constructor(private emailService: EmailService) {
    // Call start method here
  }
}

Need a hint?

Create a start method in EmailService that calls addJobs(). Then call this.emailService.start() in AppModule constructor.