Use click event from random generated button

[Theo]

Hi all,

Ive 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. Im now using the AddHandler command but it still doesnt work the way I want. Let me explain what I want to build. Ive 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? Ive put a breakpoint at the procedure ButtonClick and discovered that the procedure isnt 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

 

[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.