Hi,

i generate 3 dropdownlists. I have to do that with code-behind because i never know in advance how many i need. The amount comes from a database.
Dropdownlist 2 is not visible, the others are visible.
When the selectedvalue of dropdownlist 1 equals "b" then dropdownlist 3 must be visible.

I can do everything except: setting DDL3 visible when selectedvalue of DDL1 equals "b".

Here the code:

Friend dds As New List(Of DropDownList)

    Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreInit
        Dim i As Integer
        Dim lit As LiteralControl
        Dim z1, z2, z3 As ListItem
        For i = 1 To 3
            If Not IsPostBack Then
                Dim dd As New DropDownList
                dd.AutoPostBack = True
                dd.ID = i
                z1 = New ListItem("a", "a")
                z2 = New ListItem("b", "b")
                z3 = New ListItem("c", "c")
                dd.Items.Add(z1)
                dd.Items.Add(z2)
                dd.Items.Add(z3)
                Session(dd.ID) = dd.ID
                If i = 3 Then dd.Visible = False
                dds.Add(dd)
                Session("dds") = dds
            Else
                dds = CType(Session("dds"), List(Of DropDownList))
            End If
        Next

        For Each d As DropDownList In dds
            form1.Controls.Add(d)
            lit = New LiteralControl("<br>")
            form1.Controls.Add(lit)
            AddHandler d.SelectedIndexChanged, AddressOf dropd
        Next
    End Sub

    Protected Sub dropd(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim dd As DropDownList = CType(sender, DropDownList)
        If dd.ID = 1 And dd.SelectedValue = "b" Then
           [u] 'dd with ID=3 must be visible: how to do that?</u>
        End If
    End Sub
End Class

Thanks
H.

Little mistake: it's DDL 3 which is invisible and not DDL 2.

I found it:
 CType(FindControl("3"), DropDownList).Visible = False

You could save the DDLs into a list as you create then. Then you can loop through the list and look for the one you want to change.

You say that the number of DDLs is unknown (coming from a database). Will the values in the DDLs come from the database too? If so, how are you going to determine what value in one DDL should make another visible?

-Peter
compiledthoughts.com

Thanks for your suggestion.
The id of the ddl which affects others is also in a table.