在EventSubscriber中如何从URL获取参数?

$id 当它不应该是空的时候总是空的。我可以通过控制器检索$id值,但不能从EventSubscriber检索。

FilterControllerEvent

class TestVerificationSubscriber implements EventSubscriberInterface
{

    private $testService;
    public function __construct(TestService $testService)
    {
        $this->testService = $testService;
    }

    /**
     * Returns an array of event names this subscriber wants to listen to.
     *
     * The array keys are event names and the value can be:
     *
     *  * The method name to call (priority defaults to 0)
     *  * An array composed of the method name to call and the priority
     *  * An array of arrays composed of the method names to call and respective
     *    priorities, or 0 if unset
     *
     * For instance:
     *
     *  * array('eventName' => 'methodName')
     *  * array('eventName' => array('methodName', $priority))
     *  * array('eventName' => array(array('methodName1', $priority), array('methodName2')))
     *
     * @return array The event names to listen to
     */
    public static function getSubscribedEvents()
    {
        return array(
            KernelEvents::CONTROLLER => 'onKernelController',
        );
    }

    public function onKernelController(FilterControllerEvent $event){
        $controller = $event->getController();

        /*
         * $controller passed can be either a class or a Closure.
         * This is not usual in Symfony but it may happen.
         * If it is a class, it comes in array format
         */
        if (!is_array($controller)) {
            return;
        }

        if ($controller[0] instanceof TestVerificationController) {
            //this always returns null
            $id = $event->getRequest()->query->get('id');
            if(!$id){
                throw new CustomApiException(Response::HTTP_BAD_REQUEST, "Could not verify that the test exists.");
            }
            $this->testService->checkAndUpdateWithId($id);
        }
    }

}

我现在唯一的假设是,也许在这个特定的时刻,symfony还没有完全处理请求?