二级联动

//产品线改变事件
     $(function () {
         $("#ProductLineGroup").change(function () { GetSecondGroup() });
     });

     //通过产品线得到产品数据
     function GetSecondGroup() {
         $("#ProductGroup").empty();
         if ($("#ProductLineGroup").val() != "" || $("#ProductLineGroup").val() != null) {
             var url = '@Url.Content("~/ClassManager/BindProductList?productLine=")' + $.trim($("#ProductLineGroup").val());
             $.getJSON(url, function (data) {
                 var str = "";
                 $.each(data, function (i, item) {
                     str += "<option value='" + data[i].Value + "'>" + data[i].Text + "</option>";
                 })
                 $("#ProductGroup").html(str);
             });
         }
     }

 public ActionResult BindProductList(string productLine)
        {
            List<SelectListItem> productList = new List<SelectListItem>();
            SelectListItem sItem = new SelectListItem();
            sItem.Text = LangHelper.WordGet("--请选择--", this.LanguageAutoDetect);
            sItem.Value = "";
            productList.Add(sItem);

            if (!string.IsNullOrEmpty(productLine))
            {
                DataTable dtProduct = tOpClassBusiness.FindProductTable(productLine);
                if (dtProduct != null)
                {
                    foreach (DataRow item in dtProduct.Rows)
                    {
                        SelectListItem it = new SelectListItem();
                        it.Text = item["ProductLineName"].ToString();
                        it.Value = item["ProductLineID"].ToString();
                        productList.Add(it);
                    }
                }
            }
            return Json(productList, JsonRequestBehavior.AllowGet);
        }

HTML:

if (custom.FieldType == "1")
            {
              <tr>  
                  <td class="labelTdWidth tdLabelBg"><label>@ViewBag.ProductLineText</label></td>
                  <td class="textTdWidth" colspan="3"> @Html.DropDownList("ProductLineGroup", null, new { style = "" })</td> 
              </tr> 
            }
            if (custom.FieldType == "2")
            {
              <tr>         
                  <td class="labelTdWidth tdLabelBg"><label>@ViewBag.ProductText</label></td>
                  <td class="textTdWidth" colspan="3"> @Html.DropDownList("ProductGroup", null, new { style = "" })</td>      
              </tr> 
            }

ViewData["ProductLineGroup"] = FindProductLine(ViewBag.DefaultSelect);

其中这个ViewData["ProductLineGroup"]是@Html.DropDownList("ProductLineGroup"）的对应值

一般这样写也可 以：@Html.DropDownList(“iProductLineId”，"@ViewData["ProductLineGroup"]"）

 @Html.DropDownList("ProductList", ViewData["ProductList"] as IEnumerable<SelectListItem>, new { @onchange = "GetThreeGroup(this);" })

以上是原生方式，下面是easyUI方式：

HTML:

<input id="productLine" name="productLine" class="easyui-combotree"  data-options="valueField:'id',textField:'text'" panelHeight="100" style="170px;+175px;_175px;"/>
<input id="product" name="product" class="easyui-combotree"  data-options="valueField:'id',textField:'text'" panelHeight="100" style="170px;+175px;_175px;"/>

JS:

//加载产品线
            $('#productLine').combobox({
                url: '@Url.Action("GetProductLineListByDomain", "OfferingGroupByTempV4")' + "?domainId=" + $("#domainId", parent.document).html(),
                valueField: 'id',
                textField: 'text',
                onSelect: function (record) {
                    $('#product').combobox({
                        url: '@Url.Action("GetProductListByProductLine", "OfferingGroupByTempV4")' + "?productLine=" + record.id, //GetProductListByProductLine
                        valueField: 'id',
                        textField: 'text'
                    })
                }
            });

Controller:

 public ActionResult GetProductLineListByDomain(Guid domainId)
        {
            List<TSysProductLine> productLineList = ModelConvertHelper<TSysProductLine>.ConvertToModel(tOpClassBusiness.FindProductLineTable(domainId)).ToList();
            List<ComboTree> list = new List<ComboTree>();
            ComboTree combo;
            foreach (TSysProductLine p in productLineList)
            {
                combo = new ComboTree();
                combo.id = p.ProductLineID;
                combo.text = p.ProductLineName;
                list.Add(combo);
            }

            return Json(list);
        }

ComboTree.cs

public class ComboTree
    {
        private Guid _id = Guid.Empty;
        private string _text = string.Empty;
        private string _state = "open";//"closed";
        private List<ComboTree> _children = new List<ComboTree>();
        /// <summary>
        /// 
        /// </summary>
        public Guid id
        {
            get { return _id; }
            set { _id = value; }
        }
        
        /// <summary>
        /// 
        /// </summary>
        public string text
        {
            get { return _text; }
            set { _text = value; }
        }
       
        /// <summary>
        /// 状态：默认为:open, closed 关闭该节点下的子节点，open：打开该节点下的子节点
        /// </summary>
        public string state
        {
            get { return _state; }
            set { _state = value; }
        }
       
        /// <summary>
        /// 
        /// </summary>
        public List<ComboTree> children
        {
            get { return _children; }
            set { _children = value; }
        }
    }