public ActionResult Index3()

         {

             ViewBag.departments = new SelectList(getDepartments(),"d_id","d_name");//部门数据

             return View();

         }

         private List<department> getDepartments()

         {

             List<department> list = db.department.ToList();

             return list;

         }

         public JsonResult GetEmployye(int departmentId)

         {

            //通过部门id，获取该部门的员工

               var list= db.employee.Where(a => a.e_d_id == departmentId).ToList().Select(a => new SelectListItem(){Text = a.e_name,Value = a.e_id+""});

             return Json(list,JsonRequestBehavior.AllowGet);

         }

@{

    Layout = null;

}

<!DOCTYPE html>

<html>

<head>

    <meta name="viewport" content="width=device-width" />

    <script src="~/Scripts/jquery-1.8.2.min.js"></script>

    <script src="~/Scripts/knockout-2.2.0.debug.js"></script>

    <title>Index3</title>

</head>

    <body>

        <div>

            <p>选择部门：@Html.DropDownList("department",ViewBag.departments as SelectList,"请选择",new{onchange="searchEmployee();"})

            </p>

            <p data-bind="visible: selectOptions().length > 0"></p>

            <b style="color:#0094ff">员工：</b>

            <select data-bind="options: selectOptions, optionsText: 'Text', optionsValue: 'Value', optionsCaption: '请选择'"></select>

        </div>

    </body>

    <script type="text/javascript">

        function ViewModel() {

            this.selectOptions = ko.observableArray([]);

        }

        var vm = new ViewModel();

        ko.applyBindings(vm);

        function searchEmployee() {

            var id = $("#department").val();

            $.getJSON(

                "@Url.Action("GetEmployye")",

                { departmentId: id },

                function (data) {

                    vm.selectOptions(data);

                });

        }

    </script>

</html>