MVC实现下拉框联动的实例详解

@using (Html.BeginForm("aaai003sch", "aaa", FormMethod.Post, new { @class = "form-horizontal", role = "form" }))
{
 @Html.AntiForgeryToken()
 <p class="modal-body">
  <p class="form-horizontal">
    <p class="form-group">
     @Html.LabelFor(m => m.dept, new { @class = "col-sm-2 control-label" })
      <p class="col-sm-10">
       @Html.DropDownListFor(model => model.dept, Model.deptlist, new { @class = "form-control select2 ", style = "width: 100%;" })
       @Html.ValidationMessageFor(m => m.dept, "", new { @class = "text-danger" })
      </p>
    </p>
    <p class="form-group">
    @ Html.LabelFor(m => m.job, new { @class = "col-sm-2 control-label" })
      <p class="col-sm-10">
       @Html.DropDownListFor(model => model.job, Model.joblist, new { @class = "form-control select2 page-select2-area", style = "width: 100%;" })
       @Html.ValidationMessageFor(m => m.job, "", new { @class = "text-danger" })
      </p>
    </p>
  </p>
 </p>
</p>

//根据城市获取酒店
 $("#dept").change(function () {
  var url = rootUrl + "aaa/GetJobByDept";
   var dept = $(this).val(); //获取部门的值
   var job = $("#job");
   job.empty();  //清空当前职位的值
   //这句很重要，因我们用的是select2插件，若没有用这个插件可以去掉这句
   job.select2('val', '');
   $.ajax({
    cache: false,
    type: "GET",
    url: url,
    data: { "Dept": dept},
    success: function (data) {
     $.each(data, function (id, option) {

      job.append($('<option></option>').val(option.Id).html(option.Name));
     });
     job.trigger('change');
    },
    error: function (xhr, ajaxOptions, thrownError) {
     toastr["error"]("请选择部门");
    }
   });
 });

  [Description("根据部门获取职位")]
  [AcceptVerbs(HttpVerbs.Get)]
  [LoginAllowView]
  public ActionResult GetJobByDept(string dept)
  {
   if (String.IsNullOrEmpty(dept))
   {
    throw new ArgumentNullException("dept");
   }
   StringBuilder sb = new StringBuilder();
   sb = new StringBuilder();
   sb.Append(" SELECT jobid,jobname ");
   sb.Append(" FROM job_file ");
   sb.Append(" LEFT JOIN dept_file ON jobdept = deptid ");
   sb.AppendFormat(" WHERE deptid='{0}'", dept);
   DataTable dt = sqlHelper.getData(sb.ToString());
   var result = dt.AsEnumerable().Select(row => new Item
   {
    Name = Utils.ObjToStr(row["jobname"]),
    Id = Utils.ObjToInt(row["jobid"], 0)
   }).ToList();
   return Json(result, JsonRequestBehavior.AllowGet);
  }