Event Bus

The event bus enables decoupled inter-module communication. Modules emit events, other modules react — without importing each other.

Emitting Events

From any controller, use the emit function from the request context:

export async function login(request, services) {
  const { body, send, emit } = request
  const { authService } = services

  const result = await authService.login(body.email, body.password)
  await emit('auth:login', { userId: result.data.user.id })
  send(result.data)
}

Listening for Events

In a module's module.js, declare event listeners in the on property:

// modules/notifications/module.js
export default {
  name: 'notifications',
  prefix: '/notifications',

  on: {
    'order:created': 'onOrderCreated',
    'auth:login':    'onUserLogin',
  },

  routes: [],
}

The handler function receives event data + services:

// modules/notifications/notifications.controller.js

export function onOrderCreated(data, services) {
  console.log('New order!', data.orderId, data.total)
  // Send email, push notification, etc.
}

export function onUserLogin(data, services) {
  console.log('User logged in:', data.userId)
}

Manual EventBus Usage

import { EventBus } from 'SpaceNode'

const bus = new EventBus()
bus.on('test', (data) => console.log(data))
bus.once('test', (data) => console.log('only once'))
await bus.emit('test', { hello: 'world' })
bus.off('test')
bus.clear()

EventBus API

Programmatic Access via app.events

You can subscribe to events directly on the app instance using app.events:

const app = await createApp()

app.events.on('user:registered', async (data) => {
  await sendWelcomeEmail(data.email)
})

Error Handling

If an event handler throws an error, it is not swallowed. SpaceNode catches the error, logs it, and re-emits it as an event:error event:

app.events.on('event:error', ({ event, errors }) => {
  console.error(`Errors in event "${event}":`, errors)
})

The event:error payload contains:

• event — the name of the event that had failures
• errors — array of { event, error } objects, one per failed handler