The event system in ThinkPHP 6 offers a decoupled approach to handling application logic, allowing components to react to specific actions without tight dependencies.

Registering Listeners

Using Closures

Closures provide a quick way to define lightweight listeners inline.

use think\facade\Event;

Event::listen('user_login', function() {
    echo 'User login detected.';
});

Event::listen('user_login', function() {
    echo 'Logging login details.';
});

Method-Based Listeners

Stadnard Handling

Define a class where the default handle method acts as the listener.

// app/common/events/AuthAction.php
namespace app\common\events;

class AuthAction
{
    public function handle()
    {
        echo 'Authentication action executed.';
    }
}

Register it in your bootstrap or controller:

Event::listen('auth_action', 'app\common\events\AuthAction');

Custom Methods

You can map specific methods within a class to different events.

// app/common/events/AuthAction.php
namespace app\common\events;

class AuthAction
{
    public function logAttempt()
    {
        echo 'Attempt logged.';
    }

    public function notifyAdmin()
    {
        echo 'Admin notified.';
    }

    public static function writeAudit()
    {
        echo 'Audit trail written.';
    }
}

Event::listen('auth_attempt', 'app\common\events\AuthAction::writeAudit');
Event::listen('auth_attempt', ['app\common\events\AuthAction', 'logAttempt']);
Event::listen('auth_success', ['app\common\events\AuthAction', 'notifyAdmin']);

Batch Registration

To register multiple listeners for various events at once, use listenEvents.

Event::listenEvents([
    'auth_attempt' => [
        'app\common\events\AuthAction::writeAudit',
        ['app\common\events\AuthAction', 'logAttempt']
    ],
    'auth_success' => [
        ['app\common\events\AuthAction', 'notifyAdmin']
    ]
]);

Subscribers

Manual Subscription

A subscriber class can define its own binding logic via a subscribe method.

// app/common/events/AuthAction.php
namespace app\common\events;

use think\Event;

class AuthAction
{
    public function subscribe(Event $event)
    {
        $event->listen('auth_attempt', ['app\common\events\AuthAction', 'logAttempt']);
        $event->listen('auth_success', ['app\common\events\AuthAction', 'notifyAdmin']);
    }
}

Event::subscribe('app\common\events\AuthAction');

Automatic Discovery

If methods follow the on + EventName convention, they are automatically discovered.

// app/common/events/AuthAction.php
namespace app\common\events;

class AuthAction
{
    public function onAuthAttempt()
    {
        echo 'Automatic detection: AuthAttempt.';
    }

    public function onAuthSuccess()
    {
        echo 'Automatic detection: AuthSuccess.';
    }
}

Triggering the event uses the capitalized name:

Event::trigger('AuthAttempt');
Event::trigger('AuthSuccess');

Dispatching Events

Use the trigger method or the helper function to fire events.

Event::trigger('auth_success');
\event('auth_success');

Advanced Configuration

Prepending Listeners

Set the third argument of listen to true to add a listener to the beginning of the queue.

Event::listen('auth_attempt', 'app\common\events\AuthAction', true);

Triggering Only the First Listener

Pass true as the third argument to trigger to stop after the first listener executes.

Event::trigger('AuthAttempt', null, true);

Removing Listeners

Clear all listeners for a specific event using remove.

Event::remove('auth_attempt');

Event Aliasing

Create aliases to trigger the same event logic using different names.

Event::bind(['login_check' => 'app\common\events\AuthAction']);
Event::listen('login_check', ['app\common\events\AuthAction', 'logAttempt']);
Event::trigger('login_check');
Event::trigger('app\common\events\AuthAction');

Checking Listener Existence

Verify if an event has active listeners with hasListener.

if (Event::hasListener('auth_success')) {
    // Proceed with logic
}