事件系统（Events System）¶

// 在事件执行前的配置文件或者代码片段中
use Cake\Event\EventManager;

EventManager::instance()->on(
    'Model.Order.afterPlace',
    $aCallback
);

$eventsFired = EventManager::instance()->getEventList();
$firstEvent = $eventsFired[0];

use Cake\Log\Log;

$this->Orders->eventManager()->on('Model.Order.afterPlace', function ($event) {
    Log::write(
        'info',
        'A new order was placed with id: ' . $event->getSubject()->id
    );
});

$events = [
    'email-sending' => 'EmailSender::sendBuyEmail',
    'inventory' => [$this->InventoryManager, 'decrement'],
];
foreach ($events as $callable) {
    $eventManager->on('Model.Order.afterPlace', $callable);
}

// 在存储操作之前，你可以
// 创建如下, ie. config/bootstrap.php
use Cake\ORM\TableRegistry;
// 如果发送邮件
use Cake\Mailer\Email;

TableRegistry::getTableLocator()->get('ThirdPartyPlugin.Feedbacks')
    ->eventManager()
    ->on('Model.afterSave', function($event, $entity)
    {
        // 比方说我们可以给管理者发送一封邮件
        $email = new Email('default');
        $email->from('[email protected]' => 'Your Site')
            ->setTo('[email protected]')
            ->setSubject('New Feedback - Your Site')
            ->send('Body of message');
    });

// 登录监听器到事件管理器
$this->eventManager()->on('User.Registration', [$this, 'userRegistration']);
$this->eventManager()->on('User.Verification', [$this, 'userVerification']);
$this->eventManager()->on('User.Authorization', [$this, 'userAuthorization']);

// 应用的其它地方。
$events = $this->eventManager()->matchingListeners('Verification');
if (!empty($events)) {
    // 实行存在'Verification'事件监听器的逻辑
    // 比方说如果存在就移除该监听器
    $this->eventManager()->off('User.Verification');
} else {
    // 实行不存在'Verification'事件监听器的逻辑
}

// 给回调函数设定优先级
$callback = [$this, 'doSomething'];
$this->eventManager()->on(
    'Model.Order.afterPlace',
    ['priority' => 2],
    $callback
);

// 给监听器设定优先级
class UserStatistic implements EventListenerInterface
{
    public function implementedEvents()
    {
        return [
            'Model.Order.afterPlace' => [
                'callable' => 'updateBuyStatistic',
                'priority' => 100
            ],
        ];
    }
}

$this->eventManager()
    ->dispatch(new Event('View.afterRender', $this, ['view' => $viewFileName]));

function (Event $event, $viewFileName)

public function doSomething($event)
{
    // ...
    return false; // 停止事件
}

public function updateBuyStatistic($event)
{
    // ...
    $event->stopPropagation();
}

public function place($order)
{
    $event = new Event('Model.Order.beforePlace', $this, ['order' => $order]);
    $this->eventManager()->dispatch($event);
    if ($event->isStopped()) {
        return false;
    }
    if ($this->Orders->save($order)) {
        // ...
    }
    // ...
}

// 一个监听器的回调函数
public function doSomething($event)
{
    // ...
    $alteredData = $event->getData('order') + $moreData;
    return $alteredData;
}

// 另一个监听器的回调函数
public function doSomethingElse($event)
{
    // ...
    $event->setResult(['order' => $alteredData] + $this->result());
}

// 使用事件结果
public function place($order)
{
    $event = new Event('Model.Order.beforePlace', $this, ['order' => $order]);
    $this->eventManager()->dispatch($event);
    if (!empty($event->getResult()['order'])) {
        $order = $event->getResult()['order'];
    }
    if ($this->Orders->save($order)) {
        // ...
    }
    // ...
}

// 登录一个函数
$this->eventManager()->on('My.event', [$this, 'doSomething']);

// 删除一个函数
$this->eventManager()->off('My.event', [$this, 'doSomething']);

// 登录一个匿名函数
$myFunction = function ($event) { ... };
$this->eventManager()->on('My.event', $myFunction);

// 删除匿名函数
$this->eventManager()->off('My.event', $myFunction);

// 添加一个事件监听器
$listener = new MyEventLister();
$this->eventManager()->on($listener);

// 从监听器删除一个简单的事件键
$this->eventManager()->off('My.event', $listener);

// 删除监听器包含的所有回调函数
$this->eventManager()->off($listener);