laravel Junior

What is the difference between events and listeners?

Short Answer

Events represent something that happened. Listeners react to events. This decouples the triggering code from the side effects.

Detailed Answer

Events and Listeners: Events: - Represent something that happened (UserRegistered, OrderPlaced) - Carry data about what happened - Dispatched with event() helper or Dispatchable trait - Decouple the main action from side effects Listeners: - React to specific events - Perform side effects (send email, update cache, sync data) - One event can have multiple listeners - Can be queued for background processing Benefits: - Open/Closed principle: add new behaviors without modifying existing code - Testability: test listeners independently - Decoupling: core logic doesn't know about side effects - Multiple responses to one event without code changes

Code Example

Example

<?php
// Event class
class OrderPlaced
{
    use Dispatchable, SerializesModels;
    
    public function __construct(
        public readonly Order $order
    ) {}
}

// Listener
class SendOrderConfirmation
{
    public function __construct(private Mailer $mailer) {}
    
    public function handle(OrderPlaced $event): void
    {
        $this->mailer->to($event->order->user->email)
                     ->send(new OrderConfirmationMail($event->order));
    }
}

// EventServiceProvider
protected $listen = [
    OrderPlaced::class => [
        SendOrderConfirmation::class,
        UpdateInventory::class,
        NotifyAdmin::class,
    ],
];

event(new OrderPlaced($order)); // Triggers all 3 listeners

What is the difference between events and listeners?

Short Answer

Detailed Answer

Code Example

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