public function renderExcel()
    {
        $this->beforeRender();
        $list = $this->getListViewData();

        $helper = new ExcelHelper();
 
        $helper->setHeaderClosure(function ($key, $value) {
            $this->getSlim()->response()->header($key, $value);
        });

        $helper->genExcel($this, $list, $this->getExportFilename());
    }