asp.net mvc前端post提交json数据给controller，后台参数怎么对应接收

asp.net mvc前端post提交json数据给controller，后台参数如何对应接收？
前端程序

<div class="right_body">

    <div class="body">

        <div class="top_subnav">CMS内容管理平台 > 首页 > 发布文章</div>

        <div class="title_h3">

            发布文章

        </div>

        <p class="line" style="margin-top:0;">

        </p>

        <div class="news">

            <div>

                @using (Html.BeginForm(null, null, FormMethod.Post, new { id = "newsinsertform" }))

                {

                    <p><span>文章标题:</span>@Html.TextBoxFor(a => a.News_Title, new { @class = "newstitle" })</p>

                    <p><span>文章类别:</span>@Html.DropDownListFor(a => a.NewsTypes.Id, (SelectList)ViewData["NewsType"], new { @class = "newstype" })</p>

                    <p><span>图片新闻:</span>@Html.CheckBoxFor(a => a.IsPic, new { @class = "IsPic" })<input type="file" id="fileupload" name="fileupload" class="upload" /></p>

                    <p><span>文章内容:</span></p>

                    <hr />

                    <div class="htmleditor">@Html.TextAreaFor(a => a.News_Content, new { @class = "newscontent" })</div>

                }

            </div>

        </div>

        <p class="line" style="margin-top:0;">

        </p>

        <div class="f">

            <img src="~/Content/themes/manage/images/submit.gif" id="sub" />

        </div>

        <div id="element_to_pop_up">

            <div class="message">恭喜你，提交成功了！</div>

        </div>

    </div>

</div>

js代码如下：

 $("#sub").click(function () {

            if ($(".newstitle").val() != "" && $(".newstitle").val() != "标题不能为空") {

                $("#newsinsertform").ajaxSubmit({

                    type: "post",

                    dataType: "json",

                    url: "/Manage/NewsInsert",

                    data: JSON.stringify({ News_Title: $(".newstitle").val().trim(), News_Content: editor.document.getBody().getHtml(), News_Writer: "admin", IsPic: $(".IsPic").val().trim(), News_TypeId: $(".newstype").val() }),

                    success: function () {//提示提交成功

                        $("#element_to_pop_up").bPopup({

                            autoClose: true,

                            speed: 1500

                        });

                    },

                    error: function (xmlHttpRqquest, textStatus, errorThrown) {

                        alert(errorThrown);

                    }

                });

                

            } else {

                $(".newstitle").Text("<span style='color:red'>*标题不能为空<span>");

            }

        });

后台对应的controller

        /// <summary>

        /// 发布页面（）

        /// </summary>

        /// <returns></returns>

        public ActionResult NewsInsert()

        {

            var b = new NewsTypes();

            var newstypelist = b.GetList();

            var selectlist = new SelectList(newstypelist, "Id", "TypeName");

            ViewData["NewsType"] = selectlist;

            return View();

        }


        /// <summary>

        /// 发布页面

        /// </summary>

        /// <param name="str"></param>

        /// <returns></returns>

        [HttpPost]

        public ActionResult NewsInsert(M.News str)

        {

            if (!ModelState.IsValid)

            {

                return View("NewsInsert", str);

            }

            HttpFileCollection hfc = System.Web.HttpContext.Current.Request.Files;

            if (hfc.Count > 0)

            {

                String imgPath = "";

                string filename = Guid.NewGuid() + "." + hfc[0].FileName.Substring(hfc[0].FileName.LastIndexOf(".", StringComparison.Ordinal) + 1);

                imgPath = "/images/" + filename;

                String physicalPath = Server.MapPath(imgPath);

                hfc[0].SaveAs(physicalPath);

                str.News_Picture = filename;

            }

            _bn.Insert(str);

            return Json(str, JsonRequestBehavior.AllowGet);

        }

现在的问题是后台M.News str这个参数获取到的参数不全，请大家指点一下！谢谢！！！
------解决思路----------------------
model.news=request[ " 前台要穿过来的参数 "] 这样就传给model了 
------解决思路----------------------
用Request.Form["News_Title"]试一试
------解决思路----------------------
1:不用加JSON.stringify
2:js有.trim()的用法吗...我记得应该是$.trim()....

3:你的data:{}里没有把图片传过来....