dynamic controls losing event handlers

Question

User1858287507 posted
hi there, weird problem here havent done much work with mobile development but i have done loads of standard we form work. All im trying to is display a dynamic list of butttons (each representing a product), im adding an onlcik event handler to them so i can redirect to show more details

heres the code

Private mobjCard As FutureStep.DeliveredForYouBusinessClasses.Card

 Private Sub frmCardList_Activate(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles frmCardList.Activate
        Dim objCArd As FutureStep.DeliveredForYouBusinessClasses.Card
        Dim objImage As MobileControls.Image
        Dim objButton As MobileControls.Command
        If Not mobjCategory Is Nothing Then

            For Each objCArd In mobjCategory.CardCollection
                objButton = New MobileControls.Command
                objButton.Alignment = MobileControls.Alignment.Center
                objButton.Text = objCArd.Title

                objButton.ID = "btn" & objCArd.ID
                AddHandler objButton.Click, AddressOf LoadCard
                objButton.ImageUrl = "/DeliveredForYou/DeliverACard/ImageServe.aspx?id=" & objCArd.ID & "&ImageTypeId=1&Thumb=1"
                Me.pnlCardlist.Controls.Add(objButton)

            Next
        End If
    End Sub
   

    Private Sub LoadCard(ByVal sender As Object, ByVal e As System.EventArgs)
        mobjCard = New FutureStep.DeliveredForYouBusinessClasses.Card(sender.id.replace("btn", ""))
        UpdatePageObjects()

        ActiveForm = frmCard
    End Sub


The buttons load fine at first but when one is clicked 2 things fail to happen

1. the loadcard method is not run

2. frmCardList_Activate is not run!!! only Page_Load is.

i assume that .NET cant figure out which form the event came from (it needs to reloaded to rebuild the controls and reattach the events)

If this doesnt work then it effectively mean .NET mobile doesnt support dymanic controls

Tell me its not true!!

Many Thanks
Ashley

Answer 1

User1858287507 posted

my suspicions were correct, i was able to reload the dynamic controls using a session var. As you can see its is a bit of a monstrousity, coded by satan himself [;)]

 

Private mobjCard As FutureStep.DeliveredForYouBusinessClasses.Card

 

sub Page_Load()

if not session("Rediculos") is nothing then

frmCardList_Activate(me, nothing)

end if

end sub

 Private Sub frmCardList_Activate(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles frmCardList.Activate
        Dim objCArd As FutureStep.DeliveredForYouBusinessClasses.Card
        Dim objImage As MobileControls.Image
        Dim objButton As MobileControls.Command
        If Not mobjCategory Is Nothing Then

            For Each objCArd In mobjCategory.CardCollection
                objButton = New MobileControls.Command
                objButton.Alignment = MobileControls.Alignment.Center
                objButton.Text = objCArd.Title

                objButton.ID = "btn" & objCArd.ID
                AddHandler objButton.Click, AddressOf LoadCard
                objButton.ImageUrl = "/DeliveredForYou/DeliverACard/ImageServe.aspx?id=" & objCArd.ID & "&ImageTypeId=1&Thumb=1"
                Me.pnlCardlist.Controls.Add(objButton)

            Next

session("Rediculos") = true
        End If
    End Sub
   

    Private Sub LoadCard(ByVal sender As Object, ByVal e As System.EventArgs)
        mobjCard = New FutureStep.DeliveredForYouBusinessClasses.Card(sender.id.replace("btn", ""))

session.remove("Rediculos") 
        UpdatePageObjects()

        ActiveForm = frmCard
    End Sub

anyone know of a better way to this?

Answer 2

User-1113234820 posted

Mostly, you need to add the EventHandler in the Page_Load() , not in the Form_Active(), becuase, let's imagine, when you click the button, it posts back to the page, Page_Load() gets called, then it trys to find the handler, but at that point, Form_Active is not called, you know each page is a totally new page, so the event handler is not hooked up at all in the post back process.

So, what you need to do is: in the Page_Load(), add:
if (Page.IsPostback)
{
   // Create all the buttons again, and add handlers,

}
This is why it works when you put the Rediculos in Session, becuase you called the Form Active function again.