NestJS Events

Alternative event module for NestJS.

Install

yarn add nestjs-events

nestjs-events works with NestJS (9 or 10) and RxJS 7, ensure your have those installed.

yarn add @nestjs/common@^10 rxjs@^7

Usage

Register the event module in your app to be available globally

import { Module } from "@nestjs/common";
import { EventModule } from "nestjs-events";

@Module({
  imports: [
    EventModule.forRoot({
      prefix: "", // optional
    }),
  ],
})
export class AppModule {}

Or only for a specific module

import { Module } from "@nestjs/common";
import { EventModule } from "nestjs-events";

@Module({
  imports: [
    EventModule.register({
      prefix: "", // optional
    }),
  ],
})
export class MyOtherModule {}

Declare your events.

export class MyEvent {
  public readonly value: number;
  public readonly other: string;

  constructor(parameters: { value: number; other: string }) {
    this.value = parameters.value;
    this.other = parameters.other;
  }
}

You can also use the EventBuilder helper.

import { EventBuilder } from "nestjs-events";

export class MyEvent extends EventBuilder<{ value: number; other: string }>() {}

Emit events with the EventService.

import { Injectable } from "@nestjs/common";
import { EventService } from "nestjs-events";

import { MyEvent } from "./my-event.event.ts";

@Injectable()
export class MyService {
  constructor(private readonly eventService: EventService) {}

  someMethod() {
    this.eventService.emit(new MyEvent({ value: 1, other: "hello" }));
  }
}

Listen to events through the @OnEvent decorator.

import { Injectable } from "@nestjs/common";
import { OnEvent } from "nestjs-events";

import { MyEvent } from "./my-event.event.ts";

@Injectable()
export class MyService {
  @OnEvent(MyEvent)
  handleMyEvent(event: MyEvent) {
    // event.value
    // event.other
  }
}

You can subscribe to events as well, returning an Observable.

import { Injectable } from "@nestjs/common";
import { OnEvent } from "nestjs-events";

import { MyEvent } from "./my-event.event.ts";

@Injectable()
export class MyService {
  constructor(private readonly eventService: EventService) {}

  someMethod() {
    eventService.on(MyEvent).pipe().subscribe();
  }
}