NestJs Notifications

NestJs Notifications is a flexible multi-channel notification service inspired by Laravel Notifications: https://github.com/illuminate/notifications

This module is designed for sending short informational messages across a variety of delivery channels that notify users of something that occurred in your application. For example, if you are writing a billing application, you might send an "Invoice Paid" notification to your users via email and SMS channels.

You can use pre-built delivery channels in this package, or you can create your own custom channels that can be easily integrated with this package.

Installation

$ npm install nestjs-notifications --save

Usage

To make use of this package, you will need a Notification and at least one Channel. You can create your own custom channels, or you can use pre-built ones that come with this package.

Example Channels and example Notifications are below.

Once this has been done, you can be trigger notifications to be sent like so:

import { HttpService, Injectable } from '@nestjs/common';
import { NestJsNotificationsService } from 'nestjs-notifications';
import { ExampleNotification } from 'xxxx';

@Injectable()
export class ExampleService {
  constructor(private readonly notifications: NestJsNotificationsService) {}

  /**
   * Send the given notification
   */
  public async send(): Promise<void> {
    const notification = new ExampleNotification();
    this.notifications.send(notification);
  }
}

Example Channel

All channels are resolved inside the IOC container, so you can import services, such as the HttpService as you need them.

import { HttpService, Injectable } from '@nestjs/common';
import { NestJsNotificationChannel, NestJsNotification } from 'nestjs-notifications';

@Injectable()
export class ExampleHttpChannel implements NestJsNotificationChannel {
  constructor(private readonly httpService: HttpService) {}

  /**
   * Send the given notification
   * @param notification
   */
  public async send(notification: NestJsNotification): Promise<void> {
    const data = this.getData(notification);
    await this.httpService.post(notification.httpUrl(), data).toPromise();
  }

  /**
   * Get the data for the notification.
   * @param notification
   */
  getData(notification: NestJsNotification) {
    return notification.toPayload();
  }
}

Example Notification

You can specify as many channels as you want to in the broadcastOn() function.

When constructing payloads, you can specify functions to create customised payloads for each channel, or fallback to the default toPayload() method.

You can also pass any data you need into the constructor of the notification to pass to the payload constructors.

import { Type } from '@nestjs/common';
import { HttpChannel, NestJsNotificationChannel, NestJsNotification } from 'nestjs-notifications';
import { CustomChannel } from './src/your-project/custom-channel';
import { EmailChannel } from './src/your-project/email-channel';

export class ExampleNotification implements NestJsNotification {

  /**
   * Data passed into the notification to be used when
   * constructing the different payloads
   */
  private data: any;

  constructor(data: any) {
    this.data = data;
  }

  /**
   * Get the channels the notification should broadcast on
   * @returns {Type<NestJsNotificationChannel>[]} array
   */
  public broadcastOn(): Type<NestJsNotificationChannel>[] {
    return [
      HttpChannel,
      CustomChannel,
      EmailChannel
    ];
  }

  toHttp() { }

  toCustom() { }

  toEmail() { }

  /**
   * Get the json representation of the notification.
   * @returns {}
   */
  toPayload(): any {
    return this.data;
  }
}

Channels Included in this Package

HttpChannel

The HttpChannel is designed to post data to an external URL/webhook. In order to utilise the channel correctly, you need specify the httpUrl() function and return the URL. You can then choose between using the standard toPayload() method or toHttp() method to the payload specifically for this channel.

You can implement the HttpNotification interface on your Notification Class to ensure you include the right methods.

HttpChannel Class

import {
  HttpService,
  Injectable,
  InternalServerErrorException,
} from '@nestjs/common';
import { HttpNotification, NestJsNotificationChannel } from 'nestjs-notifications';

@Injectable()
export class HttpChannel implements NestJsNotificationChannel {

  constructor(private readonly httpService: HttpService) {}

  /**
   * Send the given notification
   * @param notification
   */
  public async send(notification: HttpNotification): Promise<void> {
    const message = this.getData(notification);
    await this.httpService.post(notification.httpUrl(), message).toPromise();
  }

  /**
   * Get the data for the notification.
   * @param notification
   */
  getData(notification: HttpNotification) {
    if (typeof notification.toHttp === 'function') {
      return notification.toHttp();
    }

    if (typeof notification.toPayload === 'function') {
      return notification.toPayload();
    }

    throw new InternalServerErrorException(
      'Notification is missing toPayload method.',
    );
  }
}

HttpNotification Interface

import { NestJsNotification } from 'nestjs-notifications';

export interface HttpNotification extends NestJsNotification {
  /**
   * Define the Http url to send the notification to
   * @returns {string}
   */
  httpUrl(): string;

  /**
   * Get the Http representation of the notification.
   * @returns {any} http payload data
   */
  toHttp?(): any;
}

Test

# unit tests
$ npm run test

# e2e tests
$ npm run test:e2e

# test coverage
$ npm run test:cov

Collaborating

Would appreciate any support anyone may wish to offer. Please get in contact.

License

NestJs Notifications is MIT licensed.