c# webapi 接收不到from表單傳過來的值？

如果前端不使用 application/json作爲請求content-type的話，webapi是接收不到from表單傳過來的值，查了很多資料，貼代碼

            HttpContextBase context = (HttpContextBase)Request.Properties["MS_HttpContext"];//獲取傳統context
            HttpRequestBase request = context.Request;//定義傳統request對象
            string OrderNo = request["OrderNo"];