Addhandler, button.click not firing using VB.NET

Question

I am experiencing a problem with buttons and AddHandler. It only works if I use AddHandler Button1.click, AddressOf... in Page_load, but if I create the button dynamically in on

Answer 1

Just to aid anyone who has this problem and isn't quite sure how to implement. Here's a quick example. This example starts out by displaying a dropdownlist. When user selects something from the dropdown, another dropdownlist appears. I typed this off the top of my head, so it MAY contain errors, but you get the idea =)

In the aspx file, add a placeholder:

And in your codebehind: ...

Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init

    'Store control count in viewstate
    If Not IsPostBack Then ViewState("ControlCounter") = 1

    'Rebuild dynamic controls on every postback so when page's life cycle hits Page_Load, 
    'selected values in the viewstate (asp.net default behavior) can be loaded into the dropdowns
    Build_Dynamic_Controls()
End Sub

Protected Sub Build_Dynamic_Controls()

    'Clear placeholder
    myPlaceholder.Controls.Clear()

    'This is where the control counter stored in the viewstate comes into play
    For i as Integer = 0 To CInt(ViewState("ControlCounter") -1
        Dim ddlDynamic as New DropDownList With {
            .ID = "ddlDynamicDropdown" & i,
            .AutoPostBack = True
            }
        'This is the event that will be executed when the user changes a value on the form
        'and the postback occurs
        AddHandler ddlDynamic.SelectedIndexChanged, AddressOf ddlDynamic_SelectedIndexChanged

        'Add control to the placeholder
        myPlaceholder.Controls.Add(ddl)         

        'Put some values into the dropdown
        ddlDynamic.Items.Add("Value1")
        ddlDynamic.Items.Add("Value2")
        ddlDynamic.Items.Add("Value3")

    Next i
End Sub

Protected Sub ddlDynamic_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
    'When a dropdown value is changed, a postback is triggered (autopostback=true)
    'The event is captured here and we add another dropdown.

    'First we up the control count:
    ViewState("ControlCounter") = CInt(ViewState("ControlCounter")) + 1

    'Now that the "total controls counter" is upped by one, 
    'Let's recreate the controls in the placeholder to include the new dropdown
    Build_Dynamic_Controls()
End Sub

...