NestjsHow-ToBeginner · 4 min read

How to Use Bull Queue in NestJS: Simple Guide

To use Bull queue in NestJS, install @nestjs/bull and bull packages, then import BullModule in your module with queue configuration. Create a processor class with @Processor decorator to handle jobs and add jobs to the queue using Queue service injected via @InjectQueue.

📐

Syntax

Using Bull in NestJS involves three main parts:

Importing BullModule: Register your queue with configuration.
Creating a Processor: Use @Processor('queueName') to define job handlers.
Adding Jobs: Inject Queue and use add() to enqueue jobs.

typescript

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

@Module({
  imports: [
    BullModule.forRoot({
      redis: { host: 'localhost', port: 6379 },
    }),
    BullModule.forFeature([{ name: 'myQueue' }]),
  ],
})
export class AppModule {}

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

@Processor('myQueue')
export class MyProcessor {
  @Process()
  async handleJob(job: Job) {
    // job processing logic
  }
}

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

export class SomeService {
  constructor(@InjectQueue('myQueue') private myQueue: Queue) {}

  async addJob(data: any) {
    await this.myQueue.add(data);
  }
}

💻

Example

This example shows a NestJS module that sets up a Bull queue named email. It includes a processor that logs job data and a service that adds jobs to the queue.

typescript

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

@Processor('email')
export class EmailProcessor {
  @Process()
  async handleEmailJob(job: any) {
    console.log('Processing email job:', job.data);
  }
}

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

  async sendEmail(emailData: { to: string; subject: string; body: string }) {
    await this.emailQueue.add(emailData);
  }
}

@Module({
  imports: [
    BullModule.forRoot({
      redis: { host: 'localhost', port: 6379 },
    }),
    BullModule.forFeature([{ name: 'email' }]),
  ],
  providers: [EmailProcessor, EmailService],
})
export class AppModule {}

// Usage example (e.g., in a controller or service):
// await emailService.sendEmail({ to: 'user@example.com', subject: 'Hello', body: 'Welcome!' });

Output

Processing email job: { to: 'user@example.com', subject: 'Hello', body: 'Welcome!' }

⚠️

Common Pitfalls

Common mistakes when using Bull in NestJS include:

Not importing BullModule.forRoot() with Redis config, causing connection errors.
Forgetting to register the queue with BullModule.forFeature().
Not using @Processor decorator on the processor class, so jobs are not processed.
Injecting Queue with wrong queue name or missing @InjectQueue.
Not awaiting queue.add(), which can cause lost jobs.

typescript

/* Wrong: Missing BullModule.forRoot() */
@Module({
  imports: [
    BullModule.forFeature([{ name: 'task' }]),
  ],
})
export class TaskModule {}

/* Right: Include Redis config */
@Module({
  imports: [
    BullModule.forRoot({ redis: { host: 'localhost', port: 6379 } }),
    BullModule.forFeature([{ name: 'task' }]),
  ],
})
export class TaskModule {}

📊

Quick Reference

Remember these key points when using Bull in NestJS:

Use BullModule.forRoot() once with Redis settings.
Register each queue with BullModule.forFeature().
Define processors with @Processor('queueName') and @Process().
Inject queues with @InjectQueue('queueName') to add jobs.
Always await queue.add() to ensure job is queued.

✅

Key Takeaways

Always configure BullModule.forRoot() with Redis connection before using queues.

Use @Processor and @Process decorators to handle jobs in a processor class.

Inject queues with @InjectQueue to add jobs from services or controllers.

Await queue.add() calls to ensure jobs are properly added to the queue.