NESTJS Emittery

NESTJS async Event Emitter

Installation

NPM

npm install @haorama/nestjs-emittery

YARN

yarn add @haorama/nestjs-emittery

Usage

import { EmitteryModule } from '@haorama/nestjs-emittery';
import { Module } from '@nestjs/common';

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

Dispatching Events

To dispatch (i.e., fire) an event, first inject EmitteryService using standard constructor injection:

import {EmitteryService} from '@haorama/nestjs-emittery';

constructor(private emitteryService: EmitteryService) {}

Then use it in a class as follows:

this.emitteryService.emit(
  'order.created',
  new OrderCreatedEvent({
    orderId: 1,
    payload: {},
  }),
);

or directly using class, this will automatically use constructor.name as eventName:

this.emitteryService.emit(
  new OrderCreatedEvent({
    orderId: 1,
    payload: {},
  }),
);

//eventName = 'OrderCreatedEvent'

Listening to Events

To declare an event listener, decorate a method with the @OnEvent() decorator preceding the method definition containing the code to be executed, as follows:

import { OnEvent } from '@haorama/nestjs-emittery';

@OnEvent('order.created')
handleOrderCreatedEvent(payload: OrderCreatedEvent) {
  // handle and process "OrderCreatedEvent" event
}

//if using class as name
@OnEvent(OrderCreatedEvent.name)
handleOrderCreatedEvent(payload: OrderCreatedEvent) {
  // handle and process "OrderCreatedEvent" event
}