使用CascadingDropDown联动下拉菜单，我希望提交后保持每个菜单的选择项不变

悬赏园豆：40 [已关闭问题] 关闭于 2013-04-18 09:48

我的controller页面是这样的：

 public ActionResult Index(int? id,string lb)
        {
            ViewBag.DlistProClass = new SelectList(_db.ProClasses, "CodeClass", "Name",lb);

            var stockslist = _db.Stocks.Where(s=>s.AddDate==DateTime.Today).OrderBy(s=>s.Id).ToPagedList(id?? 1,20);
            return View(stockslist);
        }

        //根据产品类型编码返回材质列表
        public ActionResult MaterialByClass(string lb)
        {
            var materials = _db.Products.Where(m => m.CodeClass == lb).ToList().Select(a => new SelectListItem() { Text = a.Material.Name != null ? a.Material.Name : "[NO Date}", Value = a.CodeMaterial});
            return Json(materials.Distinct());
        }
        //根据材质编码返回产品规格
        public ActionResult SpecByMaterial(string cz)
        {
            var specs = _db.Products.Where(s => s.CodeMaterial == cz).ToList().Select(s => new SelectListItem() { Text = s.Spec.Name != null ? "Φ"+s.Spec.Name+"mm" : "[No Date]", Value = s.CodeSpec,Selected=true  });
            return Json(specs);
        }

View页面是这样的：

 <script type="text/javascript">
        $(document).ready(function () {
            $("#CodeMaterial").CascadingDropDown("#lb", '/Home/MaterialByClass');
            $("#CodeSpec").CascadingDropDown("#CodeMaterial", '/Home/SpecByMaterial');
        });
        $(document).ready(function () {
            $("#lb").change();
        });

    </script>
<div id="Fiter">
  <div id="search">
  @using (Html.BeginForm("Index", "Home", FormMethod.Get, new { name = "nbform" }))
  {
  <table width="770" border="0" cellspacing="0" cellpadding="0">

  <tr>
    <td width="50" align="right">品名：</td>
    <td>@Html.DropDownList("lb", ViewBag.DListProClass as SelectList, "--全部--", new { @style = "width:80px" })</td>
    <td width="50" align="right">材质：</td>
    <td>    
        <select id="CodeMaterial" name="cz"></select>    
    </td>
    <td width="50" align="right">规格：</td>
    <td>
     <select id="CodeSpec" name="gg"></select>
    </td>
    
    <td width="260"><img alt="点击搜索" src="/Content/images/searchbtn.gif" onclick="document.forms['nbform'].submit()" style="cursor:pointer"/></td>
  </tr>
  </table>
  }