DefaultController::actionExplain PHP Method

    public function actionExplain($tag, $num, $connection)
    {
        $this->loadData($tag);
        $dbPanel = $this->getOwner()->panels['db'];
        if (!$dbPanel instanceof Yii2DbPanel) {
            throw new Exception('Yii2DbPanel not found');
        }
        if (!$dbPanel->canExplain) {
            throw new CHttpException(403, 'Forbidden');
        }
        $message = $dbPanel->messageByNum($num);
        if ($message === null) {
            throw new Exception("Not found query by number {$num}");
        }
        $query = $dbPanel->formatSql($message, true);
        /* @var CDbConnection $db */
        $db = Yii::app()->getComponent($connection);
        if (!Yii::app()->request->isAjaxRequest) {
            $this->getOwner()->setLock($tag, true);
            $this->render('explain', array('tag' => $tag, 'summary' => $this->summary, 'manifest' => $this->getManifest(), 'panels' => $this->getOwner()->panels, 'dbPanel' => $dbPanel, 'connection' => $db, 'procedure' => Yii2DbPanel::getExplainQuery($query, $db->driverName), 'explainRows' => Yii2DbPanel::explain($query, $db)));
        } else {
            $this->renderPartial('_explain', array('connection' => $db, 'explainRows' => Yii2DbPanel::explain($query, $db)));
        }
    }