点击复选框会导致onCheckedChanged开火两次 [英] Clicking checkbox causes onCheckedChanged to fire twice

问题描述

我有一个复选框一个TemplateField的GridView。我的目标是使用自动回发，并设置数据库标志捕捉onclick事件。我唯一​​的问题是，事件火的两倍。第一次的复选框（在发送参数）持有点击的价值，所以我将它基于点击。第二次sender参数都具有始终检查=假的复选框。我很高兴地招待接近解决这一问题上的其他建议，但我的目标是基于用户勾选复选框来设置数据库标志。我针对的.NET Framework 2.0。

下面是相关的code：

 ＆LT; D​​IV的风格=保证金左：1EM;保证金右：1EM;＆GT;
    ＆LT; ASP：GridView控件ID =RouteGridView=服务器AllowPaging =真
            的AutoGenerateColumns =FALSE的cellpadding =4的DataKeyNames =ROUTE_NUMBER
            前景色=＃333333网格=无的风格=宽度：100％;
        onselectedindexchanged =RouteGridView_SelectedIndexChanged
        AllowSorting =真onpageindexchanging =RouteGridView_PageIndexChanging
        onsorting =RouteGridView_Sorting＆GT;
            ＆LT;柱体和GT;
＆LT;％ - 一列 - ％GT;
＆LT; ASP：的TemplateField的HeaderText =路由SORTEX pression =ROUTE_NUMBER＆GT;
    ＆LT;＆ItemTemplate中GT;
        ＆LT; ASP：LinkBut​​ton的ID =HyperLink1=服务器的CommandName =选择CommandArgument ='＆LT;％＃的eval（ROUTE_NUMBER）％＆GT;'
                            文字='＆LT;％＃的eval（ROUTE_NUMBER）％＆GT;' ＆GT;＆LT; / ASP：LinkBut​​ton的＆GT;
    ＆LT; / ItemTemplate中＆GT;
    ＆LT; ItemStyle Horizo​​ntalAlign =中心/＆GT;
＆LT; / ASP：的TemplateField＆GT;＆LT;％ - 第2列，这是哪里出了问题复选框 - ％GT;
＆LT; ASP：的TemplateField的HeaderText =阅读？
    SORTEX pression =READ_FLAG＆GT;
    ＆LT;＆ItemTemplate中GT;
        ＆LT; ASP：复选框ID =CheckBox1=服务器
            OnCheckedChanged =ChangeReadFlag
            的AutoPostBack =真
            选中='＆LT;％＃（字符串）的DataBinder.Eval（的Container.DataItem，READ_FLAG）==1％GT;'启用='＆LT;％＃isSelectedRow（集装箱）％GT;' /＆GT;
    ＆LT; / ItemTemplate中＆GT;
    ＆LT; ItemStyle Horizo​​ntalAlign =中心/＆GT;
＆LT; / ASP：的TemplateField＆GT;＆LT;％ - 更多的列 - ％
＆LT;％ - 更多的列 - ％GT;
＆LT; /专栏＆GT;
＆LT; / ASP：GridView的＆GT;
 

下面是从code背后的事件处理程序：

 保护无效ChangeReadFlag（对象发件人，EventArgs的发送）
{
    如果（RouteGridView.SelectedIndex！= -1）
    {
        复选框CB =（（复选框）发送者）;
        DataKey键= RouteGridView.SelectedDataKey;        // ...做的东西在这里...
    }
}
 

解决方案

有可能有几个原因，这样的行为。在我的情况是，事件被注册两次：
作为复选框定义结果的一部分自动一次
＆LT; ASP：复选框ID =CheckBox1=服务器
            ** OnCheckedChanged =ChangeReadFlag**
            的AutoPostBack =真
            选中='＆LT;％＃（字符串）的DataBinder.Eval（的Container.DataItem，READ_FLAG）==1％GT;'启用='＆LT;％＃isSelectedRow（集装箱）％GT;' /＆GT;

和第二次 - 一个明确的定位介于code，通常在OnInit方法：结果
CheckBox1.CheckedChanged + =新的EventHandler（ChangeReadFlag）;

为了解决这个问题，您应该从后面或从控制code删除第二个注册。

I have a GridView with a TemplateField with a checkbox. My goal is to capture the onclick event using autopostback and setting a database flag. My only problem is that the event fire's twice. The first time The Checkbox (In the sender parameter) holds the clicked value so I set it based on the click. The second time the sender parameter has a checkbox that is always checked=false. I am happy to entertain suggestions on other approached to solving this problem but my goal is to set a database flag based on the user checking a checkbox. I am targeting .NET Framework 2.0.

Here is the associated code:

<div style="margin-left : 1em;margin-right:1em;">
    <asp:GridView ID="RouteGridView" runat="server" AllowPaging="True" 
            AutoGenerateColumns="False" CellPadding="4" DataKeyNames="ROUTE_NUMBER" 
            ForeColor="#333333" GridLines="None" style="width:100%;" 
        onselectedindexchanged="RouteGridView_SelectedIndexChanged" 
        AllowSorting="True" onpageindexchanging="RouteGridView_PageIndexChanging" 
        onsorting="RouteGridView_Sorting" >
            <Columns>
<%-- Column one --%>
<asp:TemplateField HeaderText="Route" SortExpression="ROUTE_NUMBER">
    <ItemTemplate>
        <asp:LinkButton ID="HyperLink1" runat="server" CommandName="Select" CommandArgument='<%#Eval("ROUTE_NUMBER")%>'  
                            Text='<%# Eval("ROUTE_NUMBER") %>' ></asp:LinkButton>
    </ItemTemplate>
    <ItemStyle HorizontalAlign="Center" />
</asp:TemplateField>

<%-- Column 2 this is where the problem CheckBox is--%>
<asp:TemplateField HeaderText="Read?" 
    SortExpression="READ_FLAG">
    <ItemTemplate>
        <asp:CheckBox ID="CheckBox1" runat="server" 
            OnCheckedChanged="ChangeReadFlag"  
            AutoPostBack="true"
            Checked='<%# (string)DataBinder.Eval(Container.DataItem, "READ_FLAG") == "1" %>' Enabled='<%# isSelectedRow(Container)  %>' />
    </ItemTemplate>
    <ItemStyle HorizontalAlign="Center" />
</asp:TemplateField>

<%-- more columns --%
<%-- more columns --%>
</Columns>
</asp:GridView>

Here is the event handler from the code behind:

protected void ChangeReadFlag(object sender, EventArgs e)
{
    if (RouteGridView.SelectedIndex != -1)
    {
        CheckBox cb = ((CheckBox)sender);
        DataKey key = RouteGridView.SelectedDataKey;

        //... do stuff here ...
    }
}

解决方案

There could be several reasons for such behavior. In my case it was that the event was being registered twice: one time automatically as a part of the checkbox definition
<asp:CheckBox ID="CheckBox1" runat="server" **OnCheckedChanged="ChangeReadFlag"** AutoPostBack="true" Checked='<%# (string)DataBinder.Eval(Container.DataItem, "READ_FLAG") == "1" %>' Enabled='<%# isSelectedRow(Container) %>' />

and the second time - an explicit registration somewhere in code, usually in OnInit method:
CheckBox1.CheckedChanged += new EventHandler(ChangeReadFlag);

In order to fix it, you should remove the second registration either from the code behind or from your control.

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