Event Dispatcher

The event dispatcher provides a simple pub/sub system. Components fire events when things happen; other components listen and react. Events are notifications-they inform you that something occurred but shouldn't be used to modify the core flow.

Listening for Events #

$events = app('events');

$events->listen('page.saved', function (array $page) {
    // React to page being saved
    $this->cache->flush('pages');
    $this->searchIndex->update($page);
});

Listeners receive whatever payload was passed when the event was dispatched.

Dispatching Events #

$events->dispatch('page.saved', [
    'id' => $page->id,
    'slug' => $page->slug,
    'title' => $page->title,
]);

The second argument can be any value-typically an array with relevant data.

Multiple Listeners #

You can register multiple listeners for the same event. They run in registration order:

$events->listen('user.registered', function ($user) {
    // Send welcome email
});

$events->listen('user.registered', function ($user) {
    // Log registration
});

$events->listen('user.registered', function ($user) {
    // Notify admin
});

Checking for Listeners #

if ($events->hasListeners('cache.cleared')) {
    // At least one listener is registered
}

Listing Registered Events #

$eventNames = $events->getEvents();
// ['page.saved', 'user.registered', ...]

Removing Listeners #

Remove all listeners for an event:

$events->forget('page.saved');

Common Patterns #

Cache Invalidation #

$events->listen('page.saved', function ($page) {
    app('cache.tags')->flush('pages');
    app('cache')->delete('page:' . $page['slug']);
});

$events->listen('page.deleted', function ($page) {
    app('cache.tags')->flush('pages');
});

Audit Logging #

$events->listen('page.saved', function ($page) {
    app('logger')->info('Page saved', [
        'slug' => $page['slug'],
        'user' => auth_user()?->id,
    ]);
});

Webhooks #

$events->listen('order.completed', function ($order) {
    // Queue webhook notification
    dispatch(new SendWebhook('order.completed', $order));
});

Registering in Service Providers #

The best place to register listeners is in your service provider's boot() method:

class BlogServiceProvider extends ServiceProvider
{
    public function boot(): void
    {
        $events = $this->app->make('events');
        
        $events->listen('page.saved', [$this, 'onPageSaved']);
        $events->listen('page.deleted', [$this, 'onPageDeleted']);
    }
    
    public function onPageSaved(array $page): void
    {
        // Handle event
    }
}

Best Practices #

• Keep listeners fast - don't do heavy work synchronously
• Don't modify core flow - events are for side effects, not control
• Use descriptive names - entity.action format works well
• Pass minimal data - include IDs rather than full objects when possible
• Handle failures gracefully - one listener failing shouldn't break others