LinkButton PostBack handler in custom control

Question

User1291940830 posted

Hi,

Pls I'm having a problem with dynamically created LinkButtons in
a WebControl.Actually I'm implementing a Tab control with multiple tabs and I'm using LinkButtons for the Tab headers... u get the picture.

There is a TabVIewContainer containing multiple TabView items contained in a TabViewCollection.The TabViewContainer registers for an event raised by each TabView header linkbutton.   
So, when a LinkButton for a tab is clicked, its supposed to fire an event that will be handled by the tabcontainer to change the ActiveTabViewIndex i.e. to switch views to another tab.

Problem is the markup generated looks okay( the href=__doPostBack part), but for reasons I cannot explain, the event handler is not been called, both from the TabView control itself and the TabContainer.

Tried implementing IPostBackEventHandler, but did'nt help too.
Any help will be greatly appreciated.

Thanks,

Ozzy

Answer 1

User481221548 posted

Hi Ozzy and welcome

How are you apply the dynamic controls?
Please provide us some sample code, how do done that.

Answer 2

User1291940830 posted

Hi Peter,

The ASP.Net markup for the control looks like this:

<cc:TabViewContainer id="container" runat="server">

 <Views>

 <cc:TabView runat="server" ID="tab1" HeaderText="Tab 1" >

<!----some content------------!>

</cc:TabView> 

 <cc:TabView runat="server" ID="tab2" HeaderText="Tab 2">

<!----some content------------!>

</cc:TabView> 

 </Views>

</cc:TabViewContainer> 

----end----

 

its supposed to display all the headers as LinkButtons

Code from TabView to add LinkButtons

----------------------------------------------------------

protected internal virtual void RenderHeader ( HtmlTextWriter writer )
        {
           
            if ( _header != null )
            {
                _header.HtmlTag = System.Web.UI.HtmlTextWriterTag.Span;

                if ( Active )
                {
                    _header.CssClass = _owner.ActiveHeaderCssClass;
                }
                else
                {
                    _header.CssClass = _owner.InActiveHeaderCssClass;
                }
          
                LinkButton lnk = new LinkButton();
                lnk.Text = HeaderText;
                lnk.Attributes ["ViewIndex"] = ViewIndex.ToString(); ;

                lnk.Click += new EventHandler(OnSelectView);
                _header.Controls.Add(lnk);
               
               
                _header.RenderControl(writer);
            }
            else
            {
                _header = new ControlContentPanel();
                _header.HtmlTag = System.Web.UI.HtmlTextWriterTag.Span;
               
                if ( Active )
                {
                    _header.CssClass = _owner.ActiveHeaderCssClass;
                }
                else
                {
                    _header.CssClass = _owner.InActiveHeaderCssClass;
                }
          
                _header.RenderControl(writer);
            }
          
           
        }

Handler code from TabView for lnkButton_OnClick

---------------------------------------------------------------------------

protected  void OnSelectView ( object sender, EventArgs e )
        {

          EventHandler Handler = Events [_eventViewSelected] as EventHandler;
            if ( Handler != null ) Handler(sender, e);
          }

 

void IPostBackEventHandler.RaisePostBackEvent ( string eventArgument )
        {

            LinkButton lnk = new LinkButton();
            lnk.Text = HeaderText;
            lnk.Attributes ["ViewIndex"] = ViewIndex.ToString(); ;

            EventHandler Handler = Events [_eventViewSelected] as EventHandler;
            if ( Handler != null ) Handler(lnk, EventArgs.Empty);

        }

 

 

Code to handle TabClick from TabViewContainer

--------------------------------------------------------------------- 

protected internal void OnViewSelected ( object sender, EventArgs e )
        {
            LinkButton lnk = sender as LinkButton;
            int index =int.Parse( lnk.Attributes ["ViewIndex"]);
            ActiveViewIndex = index;
          }

The display is fine and the LinkButtons  actually posts back, but my handlers are not called.

Thanks for any help,

 

Ozzy

 

Answer 3

User481221548 posted

Hi Ozzy

Assign IDs to your LinkButtons, then that should work.

Answer 4

User-1407570774 posted

 Hi there,

I have a diffrent way.

1 - Implement IPostbackEventHandler:
 

1        public class TabControl : CompositeControl, IPostBackEventHandler, INamingContainer
2        {
3    
4            #region IPostBackEventHandler Members
5    
6            void IPostBackEventHandler.RaisePostBackEvent(string eventArgument)
7            {
8                throw new System.NotImplementedException();
9            }
10   
11           #endregion
12   
13       }

 
2 - Render Headers:

  

1            public virtual TagPageCollection Pages
2            {
3                get { ... }
4            }
5    
6            protected override void RenderContents(HtmlTextWriter writer)
7            {
8                for (int i = 0; i < this.Pages.Count; i++)
9                {
10                   writer.AddAttribute(HtmlTextWriterAttribute.Href, Page.ClientScript.GetPostBackClientHyperlink(this, i)); // i is page index
11                   writer.RenderBeginTag(HtmlTextWriterTag.A);
12                   writer.RenderEndTag();
13               }
14               ...
15           }

When you select a tab RaisePostBackEvent will be called. And eventArgument's value is page index.

Hope this helps.