Use click event from random generated button

[Theo]

Hi all,

 

I've got a procedure that generates some buttons. The information needed for the buttons comes out of a database.

 

The buttons are generated fine, but how can I use the click event from the buttons?

 

This is what I have so far:

   Private Sub GetButtons()
       Dim cmd As New SqlClient.SqlCommand
       Dim da As New SqlClient.SqlDataAdapter
       Dim ds As New DataSet
       Dim RowCnt As Long

       cmd.Connection = myPublics.conn
       cmd.CommandText = "SELECT [id], text FROM folders WHERE parent IS NULL"

       ds.Clear()
       If ds.Tables.Count > 0 Then ds.Tables(0).Columns.Clear()

       da.SelectCommand = cmd
       da.Fill(ds)

       RowCnt = ds.Tables(0).Rows.Count

       If RowCnt > 0 Then
           Dim i As Long

           For i = 1 To RowCnt
               Dim btn As New Button

               btn.ID = ds.Tables(0).Rows(i - 1)(0).ToString
               btn.Text = ds.Tables(0).Rows(i - 1)(1).ToString
               btn.Width = Unit.Pixel(175)
               btn.Font.Bold = False

               pRootControls.Controls.Add(btn)

               btn = Nothing
           Next
       End If

       cmd = Nothing
       da = Nothing
       ds = Nothing
   End Sub

[PlausiblyDamp]

You can use the AddHandler command to attach an event handler at runtime, if you search these forums you should find a few examples of how AddHandler works.

[Theo]

Thanks PlausiblyDamp. I'm now using the AddHandler command but it still doesn't work the way I want. Let me explain what I want to build. I've got a database with a table named ITEMS. The table lookes like this:

 

   ID          TEXT            TYPE            PARENT          LINK
   100000      Button1         folder          <NULL>          <NULL>
   100001      Button2         folder          <NULL>          <NULL>
   100002      Button11        folder          100000          <NULL>
   100003      Button12        folder          100000          <NULL>
   100004      Document111     item            100002          document111.pdf
   100005      Document112     item            100002          document112.pdf
   100006      Document113     item            100002          document113.pdf

 

On the left side of my webpage I want to make a menu out of buttons. These buttons should be generated in runtime from the data out of the table above. When I load the page the buttons with no parent are shown correctly, but when I click one of those buttons all buttons disapear.

 

What am I doing wrong? I've put a breakpoint at the procedure ButtonClick and discovered that the procedure isn't even triggered. Does this have something to do with the postback property?

 

This is my code:

 

   Private Sub GetControls(ByVal pParent As String)
       Dim cmd As New SqlClient.SqlCommand
       Dim da As New SqlClient.SqlDataAdapter
       Dim ds As New DataSet
       Dim RowCnt As Long
       Dim i As Long

       cmd.Connection = conn

       If UCase(pParent) = "NULL" Then
           cmd.CommandText = "SELECT [id], [text] FROM items WHERE parent IS NULL ORDER BY [id]"
       Else
           cmd.CommandText = "SELECT [id], [text] FROM items WHERE parent = '" & pParent & "' ORDER BY [id]"
       End If

       ds.Clear()
       If ds.Tables.Count > 0 Then ds.Tables(0).Columns.Clear()

       da.SelectCommand = cmd
       da.Fill(ds)

       RowCnt = ds.Tables(0).Rows.Count

       pControls.Controls.Clear()

       For i = 1 To RowCnt
           Dim btn As New Button

           btn.ID = ds.Tables(0).Rows(i - 1)(0).ToString
           btn.Text = ds.Tables(0).Rows(i - 1)(1).ToString
           btn.Width = Unit.Pixel(179)

           AddHandler btn.Click, AddressOf ButtonClick

           pControls.Controls.Add(btn)

           btn = Nothing
       Next

       If UCase(pParent) <> "NULL" Then
           Dim btn As New Button

           btn.ID = pParent
           btn.Text = "Previous"
           btn.Width = Unit.Pixel(179)

           AddHandler btn.Click, AddressOf ButtonClick

           pControls.Controls.Add(btn)

           btn = Nothing
       End If

       cmd = Nothing
       da = Nothing
       ds = Nothing
   End Sub

   Private Sub ButtonClick(ByVal sender As Object, ByVal e As System.EventArgs)
       GetControls(sender.id)
   End Sub

   Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
       'Put user code to initialize the page here
       If Not Page.IsPostBack Then
           SetConnection()
           GetControls("NULL")
       End If
   End Sub

Edited December 12, 2006 by Theo

[PlausiblyDamp]

You will need to recreate the buttons each time the page is refreshed.

[Theo]

You will need to recreate the buttons each time the page is refreshed.

 

Could you give me an example of that?

[PlausiblyDamp]

You would basically need to use the same code to recreate the buttons on each page refresh including postbacks, try moving the GetControls("NULL") call to after the check for IsPostback.