如何从用户控件页面后面的代码在ListView的ItemTemplate中找到控件？

Question

actually, i'm developing a web template using ASP.NET and C#. i have a listview in a usercontrol page and inside the ItemTemplate i have a PlaceHolder as below:

<asp:PlaceHolder ID="ph_Lv_EditModule" runat="server">  </asp:PlaceHolder>

i want to access to this PlaceHolder from code behind and i have use different method as below but i couldn't access it.

PlaceHolder ph_Lv_EditModule = (PlaceHolder)lv_Uc_Module.FindControl("ph_Lv_EditModule");

or

PlaceHolder ph_Lv_EditModule = (PlaceHolder)this.lv_Uc_Module.FindControl("ph_Lv_EditModule");

could you please help me how to find this control at the code behind of my usercontrol page. appreciate your consideration.

Answer 1

A ListView typically contains more than one item, therefore the NamingContainer (searched by FindControl ) of your Placeholder is neither the UserControl, nor the ListView itself. It's the ListViewItem object. So one place to find the reference is the ListView's ItemDataBound event .

protected void ListView_ItemDataBound(object sender, ListViewItemEventArgs e)
{
    if (e.Item.ItemType == ListViewItemType.DataItem)
    {
        var ph_Lv_EditModule = (PlaceHolder)e.Item.FindControl("ph_Lv_EditModule");
    }
}

If you need the reference somewhere else, you must iterate the Items of the ListView and then use FindControl on the ListViewItem .

By the way, this is the same behaviour as in other DataBound Controls like GridView or Repeater.

Answer 2

As Tim Schmelter mentioned, you can also access your control by iterating through your ListView as follows

private void HideMyEditModule()
{
    foreach (var item in lv_Uc_Module.Items)
    {
        PlaceHolder holder = item.FindControl("ph_Lv_EditModule") as PlaceHolder;
        if (holder!= null)
            holder.Visible = false;
    }
}