Events & Listeners - Decoupled Architecture

Events & Listeners

// Create event and listener
// php artisan make:event OrderPlaced
// php artisan make:listener SendOrderConfirmation --event=OrderPlaced

// Event class
class OrderPlaced
{
    public function __construct(
        public Order $order
    ) {}
}

// Listener class
class SendOrderConfirmation implements ShouldQueue
{
    public function handle(OrderPlaced $event): void
    {
        Mail::to($event->order->user)
            ->send(new OrderConfirmationMail($event->order));
    }
}

// Register in EventServiceProvider (or auto-discovery)
protected $listen = [
    OrderPlaced::class => [
        SendOrderConfirmation::class,
        UpdateInventory::class,
        NotifyWarehouse::class,
        RecordAnalytics::class,
    ],
];

// Fire the event
event(new OrderPlaced($order));
// OR
OrderPlaced::dispatch($order);

Why Events Matter

• Single Responsibility: Your controller just creates the order and fires the event. Email, inventory, analytics, and notifications are handled by separate listeners
• Open/Closed Principle: Adding new behavior (e.g., send SMS) means adding a new listener - no changes to existing code
• Queueable Listeners: Add implements ShouldQueue to run listeners in the background. Sending emails shouldn't slow down the order process
• Event Subscribers: Group multiple listeners for related events in one class (UserEventSubscriber handles registered, login, logout)

Industry Best Practices

• Always write tests for this functionality - it's the most reliable way to catch regressions when you refactor or update packages
• Document your implementation decisions in code comments, especially when you deviate from Laravel conventions - future team members (including yourself) will thank you
• Follow the single responsibility principle: each class does one thing. If a method grows beyond 20 lines, consider extracting helper methods or moving logic to a service class
• Profile performance with Laravel Debugbar (composer require barryvdh/laravel-debugbar) during development - it shows query counts, memory usage, and timeline for every request
• Keep dependencies up to date: run composer audit regularly to check for security vulnerabilities in your package dependencies

Industry Best Practices

• Always write tests for this functionality - it's the most reliable way to catch regressions when you refactor or update packages
• Document your implementation decisions in code comments, especially when you deviate from Laravel conventions - future team members (including yourself) will thank you
• Follow the single responsibility principle: each class does one thing. If a method grows beyond 20 lines, consider extracting helper methods or moving logic to a service class
• Profile performance with Laravel Debugbar (composer require barryvdh/laravel-debugbar) during development - it shows query counts, memory usage, and timeline for every request
• Keep dependencies up to date: run composer audit regularly to check for security vulnerabilities in your package dependencies

Industry Best Practices

• Always write tests for this functionality - it's the most reliable way to catch regressions when you refactor or update packages
• Document your implementation decisions in code comments, especially when you deviate from Laravel conventions - future team members (including yourself) will thank you
• Follow the single responsibility principle: each class does one thing. If a method grows beyond 20 lines, consider extracting helper methods or moving logic to a service class
• Profile performance with Laravel Debugbar (composer require barryvdh/laravel-debugbar) during development - it shows query counts, memory usage, and timeline for every request
• Keep dependencies up to date: run composer audit regularly to check for security vulnerabilities in your package dependencies

Tip

Practice Task

Quick Quiz

Common Mistake