当用户选择 DropDownList Asp.net 中的项目时如何使标签可见

Question

我正在使用 APS.net 和 c# 我在 ModalPopupExtender 中有一个 RadioButtonList、DropDownList、Button 和标签。

    <ajaxToolkit:ModalPopupExtender ID="mpeDirector_Accept_or_Reject_Overtime" runat="server" PopupControlID="pModal_Popup_Director_Accept_or_Reject_Overtime" TargetControlID="btnModal_Popup_Dummy_TargetControlID" 
    BackgroundCssClass="modalBackground" DropShadow="True">
</ajaxToolkit:ModalPopupExtender>
<asp:Panel ID="pModal_Popup_Director_Accept_or_Reject_Overtime" runat="server" CssClass="modalPopup" BackColor="#FFFFCC" BorderColor="Black" BorderStyle="Solid" BorderWidth="2px" style="display:none;">
<asp:Label ID="lbModal_Popup_Director_Accept_or_Reject_Overtime_Message" runat="server" Font-Names="Arial" ForeColor="Red" Font-Bold="True">"Director Accept/Reject" Over Time?</asp:Label>
<asp:RadioButtonList ID="rblDirector_Accept_or_Reject" runat="server" RepeatDirection="Horizontal" >
<asp:ListItem ID="liDirector_Accept" Text="Accept" Tag="1" ></asp:ListItem>
<asp:ListItem ID="liDirector_Reject" Text="Reject" Tag="2" ></asp:ListItem>
</asp:RadioButtonList>
<br />
<br />
<div>
<asp:Label ID="lbEmployee_Hourly_Rate_Multiplier" runat="server" Font-Names="Arial" Enabled="True" ForeColor="Black" Font-Bold="True">Hourly Rate:</asp:Label>
</asp:DropDownList>

<asp:UpdatePanel ID="udpModal_Popup_Director_Authorise" runat="server" Width="430px">
</asp:UpdatePanel>
</div>
<hr></hr>
<asp:Button ID="btnModal_Popup_Director_Authorise_Cancel" runat="server" Text="Cancel" Width="174px" CausesValidation="False"/>
</asp:Panel>

当我可以根据选择的 ListItem 使标签可见或不可见时，如何在 DropDownList 上创建事件。 像这样的东西：-

Switch (DropDownList.SelectedItemIndex)
{
    case "Accept":
    {
      lbModal_Popup_Director_Accept_or_Reject_Overtime_Message.Visible = true;
      break
    }
    case "Reject":
    {
      lbModal_Popup_Director_Accept_or_Reject_Overtime_Message.Visible = false;
      break
    }
}

谢谢

Answer 1

您可以通过

SelectedIndexChanged

事件来完成此操作，例如： https://www.aspsnippets.com/Articles/1593/ASPNet-DropDownList-SelectedIndexChanged-event-example-in-C-and-VBNet/ 类似

protected void OnSelectedIndexChanged(object sender, EventArgs e)
{
    switch(DropDownList.SelectedItem.Text) {
        case "Accept":
        {
            lbModal_Popup_Director_Accept_or_Reject_Overtime_Message.Visible = true;
        } break;
        case "Reject":
        {
           lbModal_Popup_Director_Accept_or_Reject_Overtime_Message.Visible = false;
        } break;
    }
}

您还需要在

runat="server"

的标记中添加

OnSelectedIndexChanged="OnSelectedIndexChanged"

和

DropDownList

。