Introduction

In the realm of backend development, the ability to schedule tasks at specific times or intervals is often a critical requirement. Nest.js, a versatile Node.js framework, meets this need with its seamless integration of cron jobs. Cron, a time-based job scheduler found in Unix-like operating systems, empowers developers to schedule tasks to run periodically at fixed times, dates, or intervals. This blog aims to provide a comprehensive guide on utilizing cron jobs in Nest.js to efficiently schedule and manage recurring tasks within your application.

Setting Up a Nest.js Project

npm install -g @nestjs/cli
nest new nest-cron-example
cd nest-cron-example

Next, install the required dependencies.

npm install --save @nestjs/schedule

Before start using nestjs/schedule package we need to import in app.module.ts

// app.module.ts
import { Module } from '@nestjs/common';
import { ScheduleModule } from '@nestjs/schedule';

@Module({
  imports: [
    ScheduleModule.forRoot()
  ],
})
export class AppModule {}

Creating a Cron Service

In Nest.js, a service can be created to handle cron jobs. Let's generate a new service named CronService:

nest generate service cron

Now, open the cron.service.ts file and add a method to schedule a cron job:

import { Injectable, Logger } from '@nestjs/common';
import { Cron, CronExpression } from '@nestjs/schedule';

@Injectable()
export class CronService {
  private readonly logger = new Logger(CronService.name);
  @Cron(CronExpression.EVERY_5_SECONDS)
  cronisRunning() {
    this.logger.log('Cron job running...');
  }
}

In this example, we've created a new cron job that runs every 5 seconds.

Using the Cron Service

To utilize our CronService, we need to add it to a module. Open the app.module.ts file and import the CronService:

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { CronService } from './cron/cron.service';
import { ScheduleModule } from '@nestjs/schedule';

@Module({
  imports: [ScheduleModule.forRoot()],
  controllers: [AppController],
  providers: [AppService, CronService],
})
export class AppModule {}

Upon running your Nest.js application, you should observe the log message from the cron job every 5 seconds.

This guide explores how to schedule and manage recurring tasks in Nest.js using cron jobs. It covers setting up a Nest.js project, creating a Cron Service to handle scheduled tasks, and providing examples of scheduling tasks at various intervals, including a task that runs at midnight every day. Perfect for backend developers looking to implement time-based job scheduling in their applications.