下拉列表 selectedindexchanged 事件未触发 [英] Dropdownlist selectedindexchanged event is not firing
问题描述
只是我在页面上的 UpdatePanel 中有一个带有 RequiredFieldValidatior 的下拉列表，我为下拉列表启用了自动回发.
Simply I have a Dropdownlist with RequiredFieldValidatior in UpdatePanel on a page, I have enabled autopostback for the dropdownlist.
问题是 Dropdownlist selectedindex 事件没有触发.当我验证页面并发生 ant 错误时，会发生这种意外行为.
The problem is that Dropdownlist selectedindex event is not firing. This unexpected behavior happens when I validate the page and ant error occurs.
我搜索了很多但找不到解决方案
I searched a lot but unable to find the solution
我的代码如下:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script type="text/javascript">
function ValidateMe() {
if (Page_ClientValidate("vgOption")) {
alert("valid");
}
return false;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager ID="smMain" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="pnlMain" runat="server" ChildrenAsTriggers="true">
<ContentTemplate>
<table border="1" cellpadding="5" cellspacing="0">
<tr>
<td>
Option:
</td>
<td>
<asp:DropDownList runat="server" AutoPostBack="true" ID="Opt" OnSelectedIndexChanged="Opt_SelectedIndexChanged" ValidationGroup="vgOption">
<asp:ListItem Text="--Select Option--" Value="0" />
<asp:ListItem Text="Upload" />
<asp:ListItem Text="Download" />
</asp:DropDownList>
<asp:RequiredFieldValidator ID="rfv" runat="server" ControlToValidate="Opt" Display="None" InitialValue="0" ValidationGroup="vgOption" ErrorMessage="Please select an option"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td>
Postback:
</td>
<td>
<asp:Label Text="" ID="lblMessage" runat="server" />
</td>
</tr>
<tr>
<td>
</td>
<td>
<input type="button" onclick="return ValidateMe();" value="Test" title="Test" />
<asp:ValidationSummary ValidationGroup="vgOption" runat="server" ShowMessageBox="true" ShowSummary="false" DisplayMode="List" />
</td>
</tr>
</table>
</ContentTemplate>
</asp:UpdatePanel>
</form>
</body>
</html>
代码隐藏:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Opt_SelectedIndexChanged(object sender, EventArgs e)
{
lblMessage.Text = "Autopostback: " + DateTime.Now.ToString();
}
}
重新填充问题的步骤:
1. 点击下拉菜单中的第一个选项
2.点击提交按钮
3. 更改下拉列表值(这应该触发 selectedindex changed 事件，但它不会)
Steps to repopulate the issue:
1. Click first option in dropdown
2. click on submit button
3. change dropdownlist value (this should fire selectedindex changed event, but it doesn't)
PS:我不想在点击提交按钮时发生回发，这就是为什么我添加了 而不是 asp.net 按钮，
即使我添加了 asp.net 按钮也不起作用
PS: I do not want to postback to happen when the submit button is clicked that is why I added <input> instead of asp.net button,
even if I add asp.net button it doesnt work
推荐答案
在阻止回发的 JS 代码中添加了 Page_BlockSubmit = false;...
Added Page_BlockSubmit = false; in the JS code which was preventing the postback...
<script type="text/javascript">
function ValidateMe() {
if (Page_ClientValidate("vgOption")) {
alert("valid");
}
Page_BlockSubmit = false;
return false;
}
</script>
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