asp.net mvc SelectList 的selected 失效及解决方案

在asp.net mvc的强类型视图（strongly typed view）下拉列表，在Controller中设定的选择项在View上选中失效了。下面是我的代码

[AcceptVerbs(HttpVerbs.Post)] public ActionResult AllUnSendMail(FormCollection collection) { int sysId = Convert.ToInt32(collection["ddlSysid"]); int selectedVal =-1; List<SystemInfoEntity> allSys = SystemInfoClient.GetAll(); allSys.Insert(0, new SystemInfoEntity { SysID = -1, Name = "请选择" }); if (sysId > 0) { selectedVal = sysId; } SelectList serviceList = new SelectList(allSys, "SysID", "Name", selectedVal); ViewData["ddlDataSysid"] = serviceList; ViewData["Subject"] = string.Empty; var viewData = MessageQueries.GetAllUnSendMails(sysId, 1, 15); return View(viewData); }

相应的视图的下列列表

<%=Html.DropDownList("ddlDataSysid", (SelectList)ViewData["ddlDataSysid"])%>

问题就出在DropDownList的Name和ViewData相同了，只要修改一下Name如下就可以了

<%=Html.DropDownList("ddlSysid", (SelectList)ViewData["ddlDataSysid"])%>

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