What are event listeners?

Event listeners, as the name suggests, listen to events that have been assigned to them. This means that listeners have to first be manually mapped for which events they should listen to.

Mappings for Event Listeners are declared in the appropriate Service Provider, depending on what part of the platform it affects - for example, it could be a Module Service Provider or the EventServiceProvider in the app directory of Aero.

How do I add a listener to an event?

<?php

namespace App\Providers;

use Illuminate\Auth\Events\Registered;
use Illuminate\Auth\Listeners\SendEmailVerificationNotification;
use Illuminate\Foundation\Support\Providers\EventServiceProvider as ServiceProvider;
use Illuminate\Support\Facades\Event;

class EventServiceProvider extends ServiceProvider
{
    /**
     * The event listener mappings for the application.
     *
     * @var array
     */
    protected $listen = [
        Registered::class => [
            SendEmailVerificationNotification::class,
        ],
    ];

    /**
     * Register any events for your application.
     *
     * @return void
     */
    public function boot()
    {
        parent::boot();

        //
    }
}

The listener is always nested within the event which it affects so that it can pass on the event to the listener’s handle method. Remember that the listener always goes within the array instantiating from the event class.