MVC-前台调用后台action 传递upload file 参数问题

在后台获取upload file 数量的时候发现count一直为0，经检查发现了问题 ，代码如下：

前台：

var data = $("#DetailForm").serialize();

$.ajax({
url: ‘@Url.Action("SaveRequest", "RegistrationRequest")‘,
type: "POST",
dataType: "JSON",
data: data,
cache: false,
processData: false,
success: function (result) {
window.scrollTo(0, 0);
utility.hideMask();
FormSaveSuccess(result);
}
});

后台：

[HttpPost]
public ActionResult SaveRequest(DetailModel model)
{
   if (ModelState.IsValid)
   {

if (model.Type == Codes.VT.ToString() || model.Type == Codes.NT.ToString())
     {
     model.DocumentsList = Utility.BuildDocumentModel(Request.Files, model.DocumentSearchCriteria.ModuleCode,  "", "",  model.DocumentSearchCriteria.FunctionId);

if (model.DocumentsList.Count == 0)
    {
       return Json(new { HasError = true, ErrorMessage = MessageResources._NoUploadFile });
    }

}

}
}

Request.Files 里文件count ==0.

解决这个问题只需要在前台调用action脚本里加上 属性 mimeType: "mutipart/form-data",

$.ajax({
url: ‘@Url.Action("SaveRequest", "RegistrationRequest")‘,
type: "POST",
dataType: "JSON",
data: new FormData(this),

mimeType: "mutipart/form-data",

cache: false,
processData: false,
success: function (result) {
window.scrollTo(0, 0);
utility.hideMask();
FormSaveSuccess(result);
}
});