re-add your handler on every postback - asp.net

Question

when the page is loaded the following code is invoke
page load
Dim products As New LinkButton
products.Text = "Products"
testPanel.Controls.Add(products)
AddHandler products.Click, AddressOf getProducts
getProducts function
Dim testDb As New Product
Dim arr As ArrayList = testDb.DbLoop()
Dim ObjList As ProductBo
Dim ID As Integer
Dim link As LinkButton
For Each ObjtList In arr
ID= ObjtList.C_Id
link = New LinkButton
testPanel.Controls.Add(New LiteralControl("<br />"))
link.ID = ID
link.Text = ObjList.Name
link.CommandArgument = CustInt
Me.testPanel.Controls.Add(link)
AddHandler link.Click, AddressOf getProductsDetails
Next ObjList
what i want to achive when the page load i link is create Products when i click on products link it invoke an event handler call getProducts. getproducts will loop in the database to fetch all record then it will creat a link for each product name when i click on the product name it should invoke another event. my problem is how can i re add control after every postback thank u

Answer 1

Because the links are dynamically created, you have to re-create and re-add the handler for them on each postback.
On the _init event, you have to check the state you are in (before product load or after product load), then create either the Product Load link OR the Product Details link. Key is they have to be created EVERY postback AND they have to be created before the _Load event. Typically this should be done on the _Init event.
Something along the lines of this:
Private Sub Page_Init(sender As Object, e As System.EventArgs) Handles Me.Init
If ViewState.Item("ProductsLoaded") IsNot Nothing Then
If ViewState.Item("ProductsLoaded").ToString = "True" Then
GetProducts(Me, New EventArgs)
Else
CreateProductsButton()
End If
Else
CreateProductsButton()
End If
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
End Sub
Private Sub CreateProductsButton()
Dim btnProducts As New LinkButton
btnProducts.Text = "Products"
testPanel.Controls.Add(btnProducts)
AddHandler btnProducts.Click, AddressOf GetProducts
ViewState.Item("ProductsLoaded") = False.ToString
End Sub
Private Sub GetProducts(sender As Object, e As EventArgs)
' get products list here
' and set handlers for each link
ViewState.Item("ProductsLoaded") = True.ToString
End Sub
Private Sub GetProductsDetails(sender As Object, e As EventArgs)
'get product details here
End Sub