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Expressots-cron

About

Expressots-cron package is a provider for Expressots that facilitates using cron jobs through a decorator and a cron provider. Expressots-cron is buit on top of cron package for Nodejs and it includes most of it's features. Check out blew sections for further details on how to use and API.

Table of Contents

Installation

Install the package via npm:

npm install expressots-cron

Usage

Make sure to register your provider inside your app.provider.ts

import { AppExpress } from "@expressots/adapter-express";
import {
    Env,
    IMiddleware,
    Middleware,
    provide,
    ProviderManager,
} from "@expressots/core";
import { container } from "../../app.container";
import { CronProvider } from "expressots-cron";

@provide(App)
export class App extends AppExpress {
    private middleware: IMiddleware;
    private provider: ProviderManager;

    constructor() {
        super();
        this.middleware = container.get<IMiddleware>(Middleware);
        this.provider = container.get(ProviderManager);
    }

    protected configureServices(): void {
        this.provider.register(Env);
        this.provider.register(CronProvider); // register here
    }

    protected postServerInitialization(): void {
        if (this.isDevelopment()) {
            this.provider.get(Env).checkAll();
        }
    }

    protected serverShutdown(): void {}
}

use it inside a controller file or a usecase.

using the decorator:

import { controller } from "@expressots/adapter-express";
import { AppUseCase } from "./app.usecase";
import { CronProvider, Cron } from "expressots-cron";
import { postConstruct } from "inversify";

@controller("/")
export class AppController {
    constructor(
        private appUseCase: AppUseCase,
        private cronProvider: CronProvider,
    ) {}

    @postConstruct() // must use postConstruct from inversify, if not the cron will not run automatically.
    init() {
        this.runCron();
    }

    @Cron("*/2 * * * * *", { name: "cronjob", timezone: "America/New_York" }) // if no name is assigned, a random uuid is generated
    public runCron() {
        console.log("cron running !");
        //
        const job = this.cronProvider.getTask("cronjob"); // retrieves a job by a provided name
        console.log(job); // typeof job is CronJob
    }
}

using the provider:

import { controller } from "@expressots/adapter-express";
import { AppUseCase } from "./app.usecase";
import { CronProvider, Cron } from "expressots-cron";
import { postConstruct } from "inversify";

@controller("/")
export class AppController {
    constructor(
        private appUseCase: AppUseCase,
        private cronProvider: CronProvider,
    ) {}

    @postConstruct()
    init() {
        this.runCron();
    }

    public runCron() {
        const job = this.cronProvider.schedule(
            "*/2 * * * * *",
            () => {
                console.log("cron running");
            },
            {
                name: "MyCronJob",
                startImmediately: false, // set to true to start the job immediately
            },
        );

        job.start();
    }
}

API

The cron package uses a simple and familiar cron syntax to define recurring tasks. The syntax consists of five fields:

* * * * *
| | | | |
| | | | └── Day of the week (0 - 7) (Sunday to Saturday)
| | | └──── Month (1 - 12)
| | └────── Day of the month (1 - 31)
| └──────── Hour (0 - 23)
└────────── Minute (0 - 59)

For example:

  • * * * * * – Run the task every minute.
  • 0 0 * * * – Run the task every day at midnight.

Cron Decorator

@Cron("*/2 * * * * *", options)

options are:

export interface ScheduleOptions {
  /**
   * The timezone that is used for job scheduling
   */
  timezone?: string;

  /**
   * Specifies whether to start the job immediately
   *
   * Defaults to `true`
   */

  startImmediately?: boolean;

  /**
   * The function to execute when the job completes
   * @returns void
   */

  onCompleted?: () => void;

  /**
   * The schedule name
   */
  name?: string;
}

Cron Provider

methods that are available on the provider:

export interface ICron {
  /**
   * Creates a new task to execute the given function when the cron expression ticks.
   * @param cronExpression
   * @param func
   * @param options
   */
  schedule(cronExpression: string, func: () => void, options?: ScheduleOptions): CronJob;

  /**
   * Get the list of tasks created using the `schedule` function
   */
  getTasks(): Map<string, CronJob>;

  /**
   * Get a specific task created using the `schedule` function
   * @param name
   */
  getTask(name: string): CronJob;
}

Methods

start: Initiates the job.

stop: Halts the job.

setTime: Modifies the time for the CronJob. Parameter must be a CronTime.

lastDate: Provides the last execution date.

nextDate: Indicates the subsequent date that will activate an onTick.

nextDates(count): Supplies an array of upcoming dates that will initiate an onTick.

fireOnTick: Allows modification of the onTick calling behavior.

addCallback: Permits addition of onTick callbacks.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Author Lhon Rafaat Mohammed