Events

App events are handle by emmitter service.

The service allow to emit and listen to events throughout the application.

import { emmitter } from '@sidekick-coder/zenith/server';

emmitter.on('user:created', ({ user }) => {
    console.log('New user created:', user);
});

Listening to events

To listen to an event, use the emmitter.on(eventName, handler) method. The handler function will receive the payload of the event as an argument.

emmitter.on('order:placed', ({ orderId, userId }) => {
    console.log(`Order ${orderId} placed by user ${userId}`);
});

Emitting events

To emit an event, use the emmitter.emit(eventName, payload) method. The payload can be any data you want to pass to the listeners.

emmitter.emit('user:created', { user: { id: 1, name: 'Alice' } });

EventContract

The EventContract interface is a helper to define the types of events and their payloads. It is a mapping of event names to their payload types.

But the event names are not limited to the keys of EventContract.

You can emit and listen to any string event name, but using EventContract allows you to have type safety and autocompletion for your events.

Also you can extend the EventContract interface in your own code to add custom events and their payload types.

// src/server/contracts/events.ts
declare module '@sidekick-coder/zenith/server' {
    export interface EventContract {
        'order:placed': { orderId: number; userId: number };
    }
}