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Delaying DataBinding

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PanelBar

This is a migrated thread and some comments may be shown as answers.

2 Answers, 1 is accepted

answered on 14 May 2009, 08:03 AM

OK, I shouldn't post right at the end of the day, 'cos, well as a description of the problem, that was pants.

Let me try again.

I've a very simple UserControl defined like this...

    
            <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="wc1.ascx.cs" Inherits="WebApplication1.wc1" %> 
        
            <%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %> 
        
            <telerik:RadPanelBar ID="RadPanelBar1" runat="server" Skin="Telerik"  
        
                OnItemDataBound="RadPanelBar1_ItemDataBound"> 
        
            </telerik:RadPanelBar>

The code behind looks like this ...

    
            using System; 
        
            using System.Collections.Generic; 
        
            using System.Linq; 
        
            using System.Web; 
        
            using System.Web.UI; 
        
            using System.Web.UI.WebControls; 
        
            using Telerik.Web.UI; 
        
            namespace WebApplication1 
        
            { 
        
                public partial class wc1 : System.Web.UI.UserControl 
        
                { 
        
                    Binding _BindData; 
        
                    ITemplate _ItemTemplate; 
        
                    public Binding BindData 
        
                    { 
        
                        get { return _BindData; } 
        
                        set { _BindData = value; } 
        
                    } 
        
                    public RadPanelBar PanelBar 
        
                    { 
        
                        get { return RadPanelBar1; } 
        
                    } 
        
                    public ITemplate ItemTemplate 
        
                    { 
        
                        get { return _ItemTemplate; } 
        
                        set { _ItemTemplate = value; } 
        
                    } 
        
                    protected override void OnInit(EventArgs e) 
        
                    { 
        
                        _BindData = Binding.Late; 
        
                        base.OnInit(e); 
        
                    } 
        
                    protected void RadPanelBar1_ItemDataBound(object sender, Telerik.Web.UI.RadPanelBarEventArgs e) 
        
                    { 
        
                        RadPanelItem i = (RadPanelItem)e.Item; 
        
                        RadPanelItem j = new RadPanelItem(); 
        
                        if (_ItemTemplate != null) j.ItemTemplate = _ItemTemplate; 
        
                        i.Items.Add(j); 
        
                        j.DataBind(); 
        
                    } 
        
                } 
        
            }

Nothing particularly clever here. All the control does is display a PanelBar in such a way as to allow the DataBound items to expand and collapse even if they contain a templated item. An example of a calling page looks like this...

    
            <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %> 
        
            <%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %> 
        
            <%@ Register src="wc1.ascx" tagname="wc1" tagprefix="uc1" %> 
        
            <!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> 
        
            </head> 
        
            <body> 
        
                <form id="form1" runat="server"> 
        
                <telerik:RadScriptManager ID="RadScriptManager1" runat="server"> 
        
                </telerik:RadScriptManager> 
        
                <div> 
        
                    <uc1:wc1 ID="wc11" runat="server" /> 
        
                </div> 
        
                </form> 
        
            </body> 
        
            </html>

With this codebehind...

    
            using System; 
        
            using System.Collections.Generic; 
        
            using System.Linq; 
        
            using System.Web; 
        
            using System.Web.UI; 
        
            using System.Web.UI.WebControls; 
        
            using Telerik.Web.UI; 
        
            namespace WebApplication1 
        
            { 
        
                public partial class WebForm1 : System.Web.UI.Page 
        
                { 
        
                    MyTreeViewTemplate template = new MyTreeViewTemplate(); 
        
                    protected override void OnInit(EventArgs e) 
        
                    { 
        
                        template = new MyTreeViewTemplate(); 
        
                        base.OnInit(e); 
        
                    } 
        
                    protected void Page_Load(object sender, EventArgs e) 
        
                    { 
        
                        wc11.PanelBar.DataSource = SiteData.Data; 
        
                        wc11.ItemTemplate = template; 
        
                        wc11.BindData = Binding.Late; 
        
                        wc11.PanelBar.DataTextField = "Text"; 
        
                        wc11.PanelBar.DataValueField = "ParentID"; 
        
                        wc11.PanelBar.DataBind(); 
        
                    } 
        
                } 
        
                public class MyTreeViewTemplate : ITemplate 
        
                { 
        
                    #region ITemplate Members 
        
                    void ITemplate.InstantiateIn(Control container) 
        
                    { 
        
                        RadTreeView view = new RadTreeView(); 
        
                        RadPanelItem item = (RadPanelItem)container; 
        
                        view.ID = "ItemTreeView"; 
        
                        view.Skin = "Telerik"; 
        
                        view.DataSource = SiteData.GetFilteredData(Convert.ToInt32(DataBinder.Eval(item.Owner, "Value"))); 
        
                        view.DataTextField = "Text"; 
        
                        container.Controls.Add(view); 
        
                    } 
        
                    #endregion 
        
                } 
        
            }

Now, this code databinds the TreeView for each PanelBarItem template as the PanelBar is loaded. What I wanted to do was have the TreeView for any given item databound on expanding the relevant PanelBar item.

I tried to do this by wiring up the Panelbar's OnItemClick event and moving the code to databind the TreeView into that event's handler. The problem is that clicking on a Panelbar item seems to break the whole thing in that the template shows very briefly and then the PanelBar item collapses again.

I think that this has something to do with the fact that the PanelBar is posting back when I click on it ('cos that's what it's supposed to do). I can't quite get my head around what I would need to do get it to work as it should, that is, binding the treeview and showing the selected panelbar item as expanded.

Can anyone offer any suggestions?

--
Stuart

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Delaying DataBinding

2 Answers, 1 is accepted