asp.net-mvc – ViewBag分配

public ActionResult SettingsList() {


        using (podio_doc_db db = new podio_doc_db() ) {

            string app_id = db.Configs.Where(r => r.Key == "app.id").Select(r => r.Value).First();
            ViewBag["app_id"] = app_id;

        }

        return View();
    }

但是我一直收到这个错误

Cannot apply indexing with [] to an expression of type 'System.Dynamic.DynamicObject'

ViewBag.app_id = app_id;

ViewBag是一种动态类型,这意味着您可以在运行时添加app_id等参数.