layui upload 后台获取不到值

后台获取不到值方法一：

<script>layui.use('upload', function () {var upload = layui.upload;//执行实例var uploadInst = upload.render({elem: '#test1' //绑定元素, url: '/Home/UploadFiles' //上传接口  , field: "fileNames"     //添加这个属性与后台名称保存一致, accept: 'file' //允许上传的文件类型, size: 500000 //最大允许上传的文件大小, before: function (obj) { //obj参数包含的信息，跟 choose回调完全一致，可参见上文。layer.load(); //上传loading
            }, done: function (res) {//上传完毕回调
                alert(res.tc);}, error: function () {//请求异常回调
            }});});
</script>

 

 public ActionResult UploadFiles(HttpPostedFileBase fileNames){string path = "";//小于20Mif (fileNames.ContentLength > 0 && fileNames.ContentLength <= 120971520){var fileName = Path.GetFileName(fileNames.FileName);string q_FN = fileName.Substring(0, fileName.LastIndexOf("."));string h_FN = fileName.Substring(fileName.LastIndexOf("."));string NewFileName = q_FN + DateTime.Now.ToString("yyyyMMddHHmmss") + h_FN;path = Path.Combine(Server.MapPath("/Uploadfile/"), NewFileName);fileNames.SaveAs(path);path = "/Uploadfile/" + NewFileName;var relt = new { tc = path };return Content(JsonConvert.SerializeObject(relt));}else{var relt = new { tc = "上传文件要小于20M" };return Content(JsonConvert.SerializeObject(relt));}}