@goodie-ts/events

Event publishing and listener support for goodie-ts. Compile-time discovery with sequential async dispatch.

Install

pnpm add @goodie-ts/events

Overview

Declarative event handling using the ApplicationEventListener abstract class pattern. The transformer plugin discovers listener subclasses at compile time and generates static wiring code. At runtime, EventBus dispatches events sequentially to registered listeners with error isolation.

Usage

import {
  ApplicationEvent,
  ApplicationEventListener,
  EventPublisher,
} from '@goodie-ts/events';
import { Singleton, Inject } from '@goodie-ts/decorators';

// Define an event class
class UserCreatedEvent extends ApplicationEvent {
  constructor(public readonly userId: string) {
    super();
  }
}

// Listen for events
@Singleton()
class UserCreatedListener extends ApplicationEventListener<UserCreatedEvent> {
  readonly eventType = UserCreatedEvent;

  async onApplicationEvent(event: UserCreatedEvent) {
    console.log(`User created: ${event.userId}`);
  }
}

// Optional: override supports() for conditional filtering
@Singleton()
class HighValueOrderListener extends ApplicationEventListener<OrderEvent> {
  readonly eventType = OrderEvent;

  supports(event: OrderEvent) {
    return event.total > 10_000;
  }

  async onApplicationEvent(event: OrderEvent) {
    console.log('High value order!');
  }

  // Optional: control execution order (lower = earlier, default 0)
  get order() {
    return 10;
  }
}

// Publish events
@Singleton()
class UserService {
  @Inject() accessor events!: EventPublisher;

  async createUser(name: string) {
    const userId = '123';
    await this.events.publish(new UserCreatedEvent(userId));
  }
}

Setup

No plugin configuration needed -- @goodie-ts/events is auto-discovered by the transformer at build time via package.json goodie.plugin field.

License

MIT