jQuery json不填充dropdownlist MVC5

Question

控制器Json结果

public JsonResult GetStaffJson( string Branch)
    {
        List<SelectListItem> S_li = new List<SelectListItem>();
        try
        {
            TempData["Staff_List"] =S_li = cmnclass.Get_staff_SelectList(Branch);
        }
        catch (Exception ex)
        {
            logger.LogError(ex);
        }
        finally
        {
        }
        return Json(S_li, JsonRequestBehavior.AllowGet);
    }

视图

        @Html.DropDownListFor(m => m.clsAUDIT.Branch, ViewBag.Branch_list as IEnumerable<SelectListItem>,"Select a Branch", new {@id="ddlBranch", @class = "form-control", @actor = "DropDown" })

和

        @Html.DropDownListFor(m=>m.clsCGT.fo_Name_CGT, TempData["Staff_List"] as IEnumerable<SelectListItem> , new {@id="ddl_CGT_fo",@class="input-sm", @actor = "DropDown", @style = "width:auto;" })

还有两个

        @Html.DropDownListFor(m => m.clsGRT.GRT_fo_Name, TempData["Staff_List"] as IEnumerable<SelectListItem>, new {@id="ddl_GRT_fo", @class = "input-sm", @actor = "DropDown", @style = "width:auto;" })
        @Html.DropDownListFor(m => m.clsGRT.GRT_bm_name, TempData["Staff_List"] as IEnumerable<SelectListItem>, new { @id = "ddl_GRT_bm", @class = "input-sm", @actor = "DropDown", @style = "width:auto;" })

现在Jquery

$('#ddlBranch').change(function () {
        var url = '@Url.Action("GetStaffJson", "Annex1")';
        var Branch = $("#ddlBranch").val();
        var ddl_CGT_fo = $("#ddl_CGT_fo");
        var ddl_GRT_fo = $("#ddl_GRT_fo");
        var ddl_GRT_bm = $("#ddl_GRT_bm");

        $.getJSON(url, { Branch: Branch }, function (response) {
            ddl_CGT_fo.empty();
            ddl_GRT_fo.empty();
            ddl_GRT_bm.empty();
            debugger;
            $.each(response, function (index, item) {
                debugger;
                var p = new Option(item.Text, item.Value);
                ddl_CGT_fo.append(p);
                ddl_GRT_fo.append(p);
                ddl_GRT_bm.append(p);
            });
        });
    });

在更改ddlBranch时，我正在填充三个DropDownList

1. ddl_CGT_fo
2. ddl_GRT_fo
3. ddl_GRT_bm

它的工作正常，但仅填充最后的DropDownList'ddl_GRT_bm'，

我在这里想念什么？ 为什么前两个DropDownList仍然为空？

Answer 1

在附加新创建的选项时，应使用.clone()函数。

var p = new Option(item.Text, item.Value);
ddl_CGT_fo.append($(p).clone());
ddl_GRT_fo.append($(p).clone());
ddl_GRT_bm.append($(p).clone());