C＃第二下拉列表不能保留選定的項目

Question

這是我第一次遇到此問題，所以請任何人幫助我。 這是我的問題，我有2個dropdownlist，第二個會從第一個dropdownlist中的選定項中填充，而在第二個dropdownlist中它將填充gridview取決於所選項。 現在的問題是，每當我從第二個ddl中選擇任何項目時，它都會回發，並且將選擇第一個項目而不是我選擇的項目。

這是我的代碼：（aspx）

                   <asp:TableRow> <%--Branch--%>
                        <asp:TableCell HorizontalAlign="Left">
                            <asp:Label ID="lblBranch" runat="server" Font-Bold="true">Branch:</asp:Label>
                        </asp:TableCell>
                        <asp:TableCell HorizontalAlign="Left">
                            <asp:DropDownList ID="ddlBranch" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlBranch_SelectedIndexChanged" AppendDataBoundItems="true" />
                        </asp:TableCell>
                    </asp:TableRow>

                    <asp:TableRow> <%--Recepient--%>
                        <asp:TableCell HorizontalAlign="Left">
                            <asp:Label ID="lblRecepient" runat="server" Font-Bold="true">Recepient:</asp:Label>
                        </asp:TableCell>
                        <asp:TableCell HorizontalAlign="left">
                            <asp:DropDownList ID="ddlRecepientDepartment" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlRecepientDepartment_SelectedIndexChanged"  AppendDataBoundItems="true" EnableViewState="true"></asp:DropDownList>
                        </asp:TableCell>
                    </asp:TableRow>

                    <asp:TableRow> <%--Gridview Recepient--%>
                        <asp:TableCell></asp:TableCell>
                        <asp:TableCell>
                            <asp:GridView ID="gvRecepientPosition" runat="server" AllowPaging="True" AutoGenerateColumns="False"
                                EmptyDataText="No Record found!" ShowFooter="false" ShowHeader="true" Width="99%" HorizontalAlign="Center" PageSize="5" OnPageIndexChanging="gvRecepientPosition_PageIndexChanging">
                                <Columns>
                                <%--<asp:TemplateField HeaderText="ID" Visible="false">
                                    <ItemTemplate>
                                    <asp:Label ID="lblID" runat="server" Text='<%# Bind("RECID") %>'></asp:Label>
                                    </ItemTemplate>
                                </asp:TemplateField>--%>
                                <asp:TemplateField HeaderText="Recepient" Visible="true">
                                     <ItemTemplate>
                                        <asp:CheckBox ID="cbRecepientPosition"  runat="server"/>
                                     </ItemTemplate>
                                </asp:TemplateField>
                                 <asp:BoundField DataField="Position" HeaderText="Position" ItemStyle-HorizontalAlign="Left" />
                                </Columns>
                            </asp:GridView>
                        </asp:TableCell>
                    </asp:TableRow>

代碼如下：

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            ddlBranch.Items.Clear();
            GetBranch();

        }


    }

    private void GetBranch()
    {
             var objManager = new EmailNotificationInfoManager();
           // ddlBranch.Items.Clear();
            ddlBranch.DataSource = objManager.EmailNotificationInfoBranch();
            ddlBranch.DataTextField = "Branch";
            ddlBranch.DataValueField = "RECID";
            ddlBranch.DataBind();

            ddlBranch.Items.Insert(0,"<--Select-->");


    }

    protected void ddlBranch_SelectedIndexChanged(object sender, EventArgs e)
    {
        var objManager = new EmailNotificationInfoManager();
        ddlRecepientDepartment.Items.Clear();
        ddlRecepientDepartment.DataSource = objManager.EmailNotificationInfoDepartment(Convert.ToInt64(ddlBranch.SelectedValue));
        ddlRecepientDepartment.DataTextField = "Department";
        ddlRecepientDepartment.DataValueField = "branchID";
        ddlRecepientDepartment.DataBind();

        ddlRecepientDepartment.Items.Insert(0,"<--Select-->");

    }

    protected void ddlRecepientDepartment_SelectedIndexChanged(object sender, EventArgs e)
    {
        var objManager = new EmailNotificationInfoManager();

        gvRecepientPosition.DataSource = objManager.GetPositionByDepartment(ddlRecepientDepartment.SelectedItem.Text);
        gvRecepientPosition.DataBind();

        Session["PositionDepartment"] = objManager.GetPositionByDepartment(ddlRecepientDepartment.SelectedItem.Text);

        ddlRecepientDepartment.Attributes.Add("onChange", "this.currentvalue = this.value;");
        //Page.Response.Redirect(HttpContext.Current.Request.Url.ToString(), true);
    }

請幫助我。 謝謝！

Answer 1

如果您是說第一個下拉列表選擇了第一個項目，則請檢查ddlBranch的EnableViewState="true"屬性

那為什么呢？

ddlRecepientDepartment.Attributes.Add("onChange", "this.currentvalue = this.value;");

Answer 2

您要做的是在事件處理程序中

 protected void ddlRecepientDepartment_SelectedIndexChanged
 (object sender, EventArgs e)
 {}

將selectedIndex屬性設置為當前所選項目的index 。