内容页面中的Findcontrols

我在我的母版页中使用以下代码来查找内容页面内的控件。在首页加载时，它工作正常;但是当我从内容页面上的下拉菜单中选择一个项目，并且启用了autopostback时，那么我得到错误“对象引用未设置为对象的实例”。这意味着FindControl（）函数无法在内容页面中找到控件。这个问题的原因是什么？内容页面中的Findcontrols

PlaceHolder pHolder = (PlaceHolder)ContentPlaceHolder2.FindControl("PlaceHolder1"); 
Label lblPage = (Label)pHolder.FindControl("lblPageName"); 
if (lblPage.Text == "DesignSerachSQGrid") 
{ 
}

编辑...

的下拉HTML代码：

<telerik:RadComboBox ID="ddlSearchL1" runat="server" Width="400px" Skin="Office2007" 
        onselectedindexchanged="ddlSearchL1_SelectedIndexChanged" 
        AutoPostBack="True" Font-Names="Eras Medium ITC" Font-Size="X-Small" 
        onprerender="ddlSearchL1_PreRender"> 
        <Items> 
         <telerik:RadComboBoxItem runat="server" Text="Please Select ................" 
          Value="Please Select ................" Font-Name="Eras Medium ITC" /> 
         <telerik:RadComboBoxItem runat="server" Text="Design Documents" 
          Value="Design Documents" Font-Name="Eras Medium ITC" /> 
         <telerik:RadComboBoxItem runat="server" Text="Vendor Documents" 
          Value="Vendor Documents" Font-Name="Eras Medium ITC" /> 
         <telerik:RadComboBoxItem runat="server" Text="Business Documents" 
          Value="Business Documents" Font-Name="Eras Medium ITC" /> 
         <telerik:RadComboBoxItem runat="server" Text="Management Documents" 
          Value="Management Documents" Font-Name="Eras Medium ITC" /> 
         <telerik:RadComboBoxItem runat="server" Text="Squad Check - Management" 
          Value="Squad Check - Management" Font-Name="Eras Medium ITC" /> 
         <telerik:RadComboBoxItem runat="server" Text="Transmittal - Management" 
          Value="Transmittal - Management" Font-Name="Eras Medium ITC" /> 
          <telerik:RadComboBoxItem runat="server" Text="Transmittal - Design" 
          Value="Transmittal - Design" Font-Name="Eras Medium ITC" /> 
          <telerik:RadComboBoxItem runat="server" Text="Squad Check - Design" 
          Value="Squad Check - Design" Font-Name="Eras Medium ITC" /> 
      <telerik:RadComboBoxItem runat="server" Text="Transmittal - Vendor" 
          Value="Transmittal - Vendor" Font-Name="Eras Medium ITC" /> 
          <telerik:RadComboBoxItem runat="server" Text="Squad Check - Vendor" 
          Value="Squad Check - Vendor" Font-Name="Eras Medium ITC" /> 
        </Items> 
      </telerik:RadComboBox>

来源

2011-10-11 chamara

你可以为MasterPage添加一些HTML吗？ – 2GDev

这是一个很长的主页，不知道html部分可能有帮助 – chamara

您可以检查这个帖子：ASP.NET 2.0 MasterPages and FindControl()

/// <summary> 
/// Finds a Control recursively. Note finds the first match and exists 
/// </summary> 
/// <param name="ContainerCtl"></param> 
/// <param name="IdToFind"></param> 
/// <returns></returns> 
public static Control FindControlRecursive(Control Root, string Id) 
{ 
    if (Root.ID == Id) 
     return Root; 

    foreach (Control Ctl in Root.Controls) 
    { 
     Control FoundCtl = FindControlRecursive(Ctl, Id); 
     if (FoundCtl != null) 
      return FoundCtl; 
    } 

    return null; 
}

使用它

this.dgItemList = FindControlRecursive(this.Master, "dgItemList") as DataGrid;

来源

2011-10-11 13:02:32

内容页面中的Findcontrols

回答

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