Yii2:多个事件附加视图

Hi,
I want try to make some dynamic sidebar and content, I have trigger event multiple times in view,
here my code:

后端/视图/布局/_sidebar.php

use commoncomponentHook;
use yiiaseEvent;

Event::trigger(Hook::className(), Hook::SIDEBAR_MENU);

后端/视图/ext/index.php

use commoncomponentHook;
use yiiaseEvent;

Event::trigger(Hook::className(), Hook::PlUGIN_CONTENT);

common/component/Hook.php

namespace commoncomponent;

use yiiaseComponent;

class Hook extends Component{

    const SIDEBAR_MENU = '';
    const PlUGIN_CONTENT = '';

}

后端插件插件index.php

namespace backendpluginsPlugin;

use Yii;
use commoncomponentHook;
use yiiaseEvent;
use yiihelpersHtml;

class Index extends Event{
    function sidebar() {
        echo '<li>' . Html::a('Menu Plugin 1', ['/ext?n=Plugin']) . '</li>';
    }

    function renderContent(){
        echo 'this is content';
    }
}

Event::on(Hook::className(), Hook::SIDEBAR_MENU, [new Index, 'sidebar']);
Event::on(Hook::className(), Hook::PlUGIN_CONTENT, [new Index, 'renderContent']);

后端pluginsPlugin2index.php

namespace backendpluginsPlugin2;

use Yii;
use commoncomponentHook;
use yiiaseEvent;
use yiihelpersHtml;

Event::on(Hook::className(), Hook::SIDEBAR_MENU, function () {
    echo '<li>' . Html::a('Menu Plugin 2', ['/ext?n=Plugin2']) . '</li>';
});

这里是我的控制器 backend/controller/ExtController.php

namespace backendcontrollers;

use Yii;
use yiiwebController;

class ExtController extends Controller
{
    public function actionIndex(){    
        return $this->render('index');
    }

}

问题:

1. 为什么它们在_sidebar.php 中出现多次?我只是在sidebar.php 中触发了SIDEBAR MENU，为什么它们同时触发了SIDEBAR_MENU 和PLUGIN_CONTENT?
2. 我在 backend/view/ext/index.php 中也有触发事件，但是没有触发 PLUGIN_CONTENT，所以内容没有出现

推荐答案

在hook.php中，它们都有相同的值，即空字符串""，它们必须有值

namespace commoncomponent;

use yiiaseComponent;

class Hook extends Component{

    const SIDEBAR_MENU = 'sidebarMenu';
    const PlUGIN_CONTENT = 'pluginContent';

}