javascript - 在后面的代码中读取时隐藏控制值不正确

Question

我在嵌套 GridView 中有一个隐藏控件来确定它是否展开。我在 javascript 函数中设置了该值。由于我设置了警报，它的设置正确。在 RowDataBound 方法中，我想读取隐藏控件以确定是否应该扩展网格。当我读取 RowDataBound 方法中的值时，它始终为“0”。我的标记很大，所以这只是嵌套网格、UpdatePanel 和隐藏控件关联:

    <asp:UpdatePanel ID="updatePnlNestedGrid" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<div id="div<%# Eval("GroupID") %>" style="display:none">                      
<asp:GridView ID="GroupMemberGridView" runat="server" AutoGenerateColumns="false" OnRowDeleting="GroupMemberGridView_RowDeleting" 
 OnRowCommand="GroupMemberGridView_RowCommand" CssClass="grid" ShowFooter="true" AllowPaging="true" PageSize="5"
  onpageindexchanging="GroupMemberGridView_PageIndexChanging" onpageindexchanged="GroupMemberGridView_PageIndexChanged">
<Columns>
    <asp:TemplateField HeaderText="MemberID">
        <ItemTemplate>
            <asp:Label ID="mggvLblMemberID" runat="server" Text='<%# Bind("MemberID") %>'></asp:Label>
        </ItemTemplate>
    </asp:TemplateField>
    <asp:TemplateField HeaderText="Member Name" ItemStyle-Wrap="false"> 
        <ItemTemplate>
            <asp:Label ID="mggvLblMemberName" runat="server" Text='<%# Bind("MemberName") %>'></asp:Label>
        </ItemTemplate>               
        <FooterTemplate>
            <asp:DropDownList ID="mggvDDLMemberName" runat="server" 
               class="chosen-single" data-placeholder="Choose member…">
            </asp:DropDownList>
            <asp:RequiredFieldValidator ID="ReqValueDDLMemberInsert" runat="server" InitialValue="0" 
                    ControlToValidate="mggvDDLMemberName" 
                    ErrorMessage="Selection required." CssClass="message-error-dropdown">
            </asp:RequiredFieldValidator>
        </FooterTemplate>
    </asp:TemplateField>
    <asp:TemplateField HeaderText="Active Device(s)">                   
        <ItemTemplate>
            <asp:Label ID="mggvLblActiveDevice" runat="server" Text='<%# (Boolean.Parse(Eval("ActiveDevice").ToString())) ? "Yes" : "No" %>'></asp:Label>
        </ItemTemplate>                   
    </asp:TemplateField>
    <asp:TemplateField HeaderText="Action" ItemStyle-Wrap="false" ItemStyle-HorizontalAlign="Center">
        <ItemTemplate>
            <asp:Button ID="mggvDeleteButton" runat="server" CausesValidation="False" CommandName="Delete" 
                Text="Delete" CssClass="gridActionbutton"  OnClientClick="return confirm('Are you sure you want to delete this Group Member?')" >
            </asp:Button>
        </ItemTemplate>                                     
        <FooterTemplate>
            <asp:Button ID="mggvAddButton" runat="server" CommandName="Add" Text="Add Member" Width="90%" 
                CssClass="gridActionbutton"/> 
        </FooterTemplate>
    </asp:TemplateField>
</Columns>
</asp:GridView>
</div>
</ContentTemplate>
</asp:UpdatePanel>      
<asp:HiddenField ID="mggvIsExpanded" runat="server" ClientIDMode="Static" Value="0" />    

这是展开/折叠网格并设置隐藏值的 JavaScript 函数:

 function DivExpandCollapse(groupID) {    
    var div = document.getElementById(groupID);
    var img = document.getElementById('img' + groupID);
    //alert shows correct hidden value
     alert($(div).parent().siblings("input:hidden[id$='mggvIsExpanded']").val());
    if (div.style.display == "none") {               
        div.style.display = "inline";
        img.src = "Images/minus.png";
        $(div).parent().siblings("input:hidden[id$='mggvIsExpanded']").val("1");   
        $("#" + div.getAttribute('id') + ".chosen-single").chosen("destroy");
        $("#" + div.getAttribute('id') + ".chosen-single").chosen({
            search_contains: true,
            width: "100%",
            placeholder_text_single: "Choose member…",
            no_results_text: "Sorry, no match!"
        });         
    }
    else {
        div.style.display = "none";
        img.src = "Images/plus.png";
        $(div).parent().siblings("input:hidden[id$='mggvIsExpanded']").val("0");
    }
}

这是事件背后的代码。我只显示隐藏值代码。:

protected void UserGroupGridView_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
      int tiGroupID = Convert.ToInt32(UserGroupGridView.DataKeys[e.Row.RowIndex].Value.ToString());
      GridView tgvGroupMember = (GridView)e.Row.FindControl("GroupMemberGridView");
        HiddenField hiddenExpand = (HiddenField)tgvGroupMember.Parent.FindControl("mggvIsExpanded");
        //This value is always "0" - the initial value
        String hiddenValue = hiddenExpand.Value.ToString(); 
   }
 }

即使隐藏值是在 JavaScript 中设置的。在后面的代码中该值始终为零，即初始值。

为什么当网格展开时，隐藏值在 RowDataBound 事件中永远不会显示为“1”？

更新我将 asp:HiddenField 放入 UpdatePanel 内的 ContentTemplate 内。但它仍然没有正确读取隐藏值。

Answer 1

您将隐藏字段视为位于 GridView 的新绑定(bind)行中。

只要保持简单，不要引用 FindControl()，而是像 mggvIsExpanded 那样直接引用控件:

protected void UserGroupGridView_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        //reference mggvIsExpanded without jumping through hoops
        String hiddenValue = mggvIsExpanded.Value.ToString(); 
    }
 }

如果该值仍然不正确，则可能意味着您试图在页面生命周期的早期引用该控件。确保代码在 Page.Load 之后运行，或者手动从 Request.Form["mggvIsExpanded"] 获取值。