Question

Here’s the situation: I have a variable number of dynamically created update panels on my page, so I thought I would write one method which handles all of the loading for each one.

My Updatepanel creation looks something like this:

 Dim newUpdp As New UpdatePanel
 newUpdatep.ChildrenAsTriggers = False
 newUpdatep.UpdateMode = UpdatePanelUpdateMode.Conditional
 newUpdatep.ID = Guid.NewGuid.ToString

 AddHandler newUpdatep.Load, AddressOf updatep_load_method
 updatep_Holder.ContentTemplateContainer.Controls.Add(newUpdp)
 updatep_Holder.Update()  

This creates the update panel and binds its load event to the method “updatep_load_method”. This method is called as soon as the Updatepanel is inserted into the holder. The method code is as follows:

Private Sub updp_load_method(sender As UpdatePanel, e As System.EventArgs)
   Dim div As New HtmlGenericControl("div")
   div.InnerText = Date.Time.Now.ToString
   sender.ContentTemplateContainer.Controls.Add(div)
   sender.Update()
End Sub

A little later on I want to update the panel, and refresh the time. So I use the javascript __doPostBack method. According to Dave Ward, the __doPostBack method follows the full page postback lifecycle, so I figured the load event of my Update panel would be fired and that “updatep_load_method” would be called by that particular update panel…

Although the partial postback occurs, and other update panel’s load events are called, my bound ones aren’t. So what’s happening here?

Answer 1

You need to recreate dynamic controls during Page_Init and have to use the same Id (so you cannot do a Guid.NewGuid.ToString() while recreating the control).

Otherwise, ASP.Net will not be able to locate your control and populate it with data from ViewState.

Here’s a good article that explains more about dynamic controls.