public function actionPay()
{
$modelDetail = new MerBase();
//实例化商家信息
$modelStu = new Students();
//实例化学生
$session = yii::$app->session;
$mer_id = $session->get('mer_id');
$user_info = $session->get('userinfo');
$payDetail = $modelDetail->getSmall($mer_id);
$user = $modelStu->getPassword($user_info['user_id']);
return $this->render('payment', ['payDetail' => $payDetail, 'user' => $user]);
}