从下拉列表中选择数据而不刷新页面

Question

在我的应用程序中，当我从下拉列表（ddlcategory）中选择类别时，数据将绑定在纯度下拉列表（ddlpurity）中。但是页面正在刷新。所以我使用更新面板来解决这个问题（页面刷新） problem.Now the data is not binding to the ddlpurity ,when data from ddlcategory is selected.How can i bind the data to ddlpurity without refreshing the page.

asp 设计页面

<asp:ScriptManager ID="ScriptManager1" runat="server"> </asp:ScriptManager>
<asp:UpdatePanel runat="server" id="UpdatePanel" updatemode="Conditional">
 <Triggers>
     <asp:Asyncpostbacktrigger controlid="ddlcategory" eventname="SelectedIndexChanged" />
   </Triggers>
       <ContentTemplate>
             <asp:DropDownList ID="ddlcategory" class="form-control txtboxmargin validate[required]" runat="server" 
               AutoPostBack="True" onselectedindexchanged="ddlcategory_SelectedIndexChanged" AppendDataBoundItems="True">
             <asp:ListItem Value="">--select category--</asp:ListItem>
           </asp:DropDownList>
       </ContentTemplate>

   </asp:UpdatePanel>

<asp:DropDownList ID="ddlpurity" 
               class="form-control txtboxmargin" AutoPostBack="True" runat="server"
               onselectedindexchanged="ddlpurity_SelectedIndexChanged">
           </asp:DropDownList>

C# 代码：

protected void ddlcategory_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (ddlcategory.SelectedItem.Text == "Gold")
        {
            BindDDLGoldPurity();
            lblheadpurity.Text = "ADD GOLD PURITY";
            txtsalesrate.ReadOnly = true;

        }
        if (ddlcategory.SelectedItem.Text == "Silver")
        {
            BindDDLSilverPurity();
            lblheadpurity.Text = "ADD SILVER PURITY";
            txtsalesrate.ReadOnly = true;

        }
        if (ddlcategory.SelectedItem.Text == "Gemstones")
        {
            txtsalesrate.ReadOnly = false;
            txtsalesrate.Text = "";

            ddlpurity.Items.Clear();

        }

    }

Answer 1

设置 AutoPostBack="False" 以摆脱刷新行为。

Answer 2

您应该包装 UpdatePanel 中的两个控件。

在第二部分。删除

AutoPostBack="true" 

来自您的DropDownList。

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel runat="server" ID="UpdatePanel" UpdateMode="Conditional">
    <Triggers>
        <asp:AsyncPostBackTrigger ControlID="ddlcategory" EventName="SelectedIndexChanged" />
    </Triggers>
    <ContentTemplate>
        <asp:DropDownList ID="ddlcategory" class="form-control txtboxmargin validate[required]"
            runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlcategory_SelectedIndexChanged"
            AppendDataBoundItems="True">
            <asp:ListItem Value="">--select category--</asp:ListItem>
        </asp:DropDownList>
        <asp:DropDownList ID="ddlpurity" class="form-control txtboxmargin" AutoPostBack="True"
            runat="server" OnSelectedIndexChanged="ddlpurity_SelectedIndexChanged">
        </asp:DropDownList>
    </ContentTemplate>
</asp:UpdatePanel>

您也可以使用javascript/jquery 来执行数据库请求。

见reference