populating variables from dynamically created controls

5 Apr 2006 6:13 PM

TB

Hi All:

I have this page where a rows / cells are programmatically added to to
table by pushing a button.

The rows contain a textbox and a associated button. What I want to is
to be able to add the content of any textbox to a global variable (and
a related session variable) when pushing the associate button.

However whenever I push the button(s) apparently the session variable
is not correctly updated and therefore nothing is updated. I have a
feeling that it has something to do with the "handles" argument in the
click event of the programmatically created buttons and / or the
dynamically assigned textbox and button names, but I am not sure.

Below is simplied version of the page

Content of sessiontest.aspx:

<%@ Page Language="vb" AutoEventWireup="false"
Codebehind="sessiontest.aspx.vb" Inherits="testsite.sessiontest"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<title>sessiontest</title>
<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5">
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
   <asp:placeholder id="plhtable" Runat="server"></asp:placeholder><br>

   <asp:Button ID="btnAddrow" Text="Add Row" Runat="server" />
</form>
</body>
</HTML>

Contant of sessiontest.aspx.vb

Public Class sessiontest
    Inherits System.Web.UI.Page

    Dim td As TableCell
    Dim tb As Table
    Dim tr As TableRow
    Dim btntest As Button
    Dim txbtest As TextBox
    DIM strResult as string ' This is where I want to store everything

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
        If Not IsPostBack Then
            tb = New Table
            addrows()
        Else
            tb = Session("table")
            strResult = Session("strResult")
        End If
        plhtable.Controls.Add(tb)
    End Sub
    Sub page_prerender(ByVal sender As Object, ByVal e As EventArgs)
Handles
MyBase.PreRender
        Session("Table") = tb
        Session("strResult") = strResult
    End Sub
    Sub addrows()
        tr = New TableRow
        txbtest = New TextBox

        td = New TableCell
        td.Text = "Enter text:"
        tr.Cells.Add(td)

        td = New TableCell
        txbtest.ID = "txbNumber" & tb.Rows.Count()
        td.Controls.Add(txbtest)
        tr.Cells.Add(td)

        td = New TableCell
        btntest = New Button
        AddHandler btntest.Click, AddressOf valuefromtxb_click
        btntest.ID = "btnNumber" & tb.Rows.Count()
        btntest.Text = "Button #" & tb.Rows.Count()

        td.Controls.Add(btntest)
        tr.Cells.Add(td)

        tb.Rows.Add(tr)
    End Sub

    Private Sub valuefromtxb_click(ByVal sender As System.Object, ByVal
e As
System.EventArgs)
        counter = counter + 1
        strResult = strResult % & txbtest.Text
    End Sub

    Private Sub btnAddrow_Click(ByVal sender As System.Object, ByVal e
As
System.EventArgs) Handles btnAddrow.Click
        addrows()
    End Sub
End Class

Any suggestions will be higly appreciated.

Thanks.

TB

6 Apr 2006 6:46 AM

Cor Ligthert [MVP]

TB,

> Any suggestions will be higly appreciated.

A simple suggestion, brign your code back to the essentials. That gives you
much more change on help in this newsgroup.

Cor

6 Apr 2006 7:23 AM

TB

I'll do anything you say, but since I am rather ignorant in these
matters, I wouldn't know how to bring my code back to those essentials
you refer to. Please advise.

TB

6 Apr 2006 7:41 AM

Cor Ligthert [MVP]

TB,

Just try it by instance with one control in one cell in a table. Probably
you find it than yourself, however, if not, than the sample you give us is
probably much easier to read.

Just my idea

Cor

6 Apr 2006 7:23 PM

TB

Following your advice, I have now simplified the code. Now no table
rows are programmatically created and subsequently filled with various
controls, but simply buttons, which when hit are supposed to change the
content of a global variable which should be displayed via a label.
However, the problem is still the same: the buttons are created but the
the line "AddHandler btntest.Click, AddressOf updateresult" doesn´t
work.

Below is the code (hopefully sufficiently reduced to the necessary
essentials):

Content of sessiontest2.aspx

<%@ Page Language="vb" AutoEventWireup="false"
Codebehind="sessiontest2.aspx.vb" Inherits="testsite.sessiontest2"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <title>sessiontest2</title>
        <meta content="Microsoft Visual Studio .NET 7.1" name="GENERATOR">
        <meta content="Visual Basic .NET 7.1" name="CODE_LANGUAGE">
        <meta content="JavaScript" name="vs_defaultClientScript">
        <meta content="http://schemas.microsoft.com/intellisense/ie5"
name="vs_targetSchema">
    </HEAD>
    <body>
        <form id="Form1" method="post" runat="server">
            <asp:placeholder id="plhtest" Runat="server"></asp:placeholder><br>
            <asp:button id="btnAddrow" Runat="server" Text="Add
Row"></asp:button><br>
            Result: <asp:label id="lblresult" Runat="server"></asp:label></form>
    </body>
</HTML>

content of sessiontest.aspx.vb

Public Class sessiontest2
    Inherits System.Web.UI.Page

    Dim counter As Integer
    Dim btntest As Button
    Dim strResult As String
    Dim plhmain As placeholder
    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
        If Not IsPostBack Then
            strResult = "nothing at the moment"
            counter = 1
            plhmain = New PlaceHolder
        Else
            plhmain = Session("plhmain")
            strResult = Session("strResult")
            counter = Session("counter")
        End If
    End Sub
    Sub page_prerender(ByVal sender As Object, ByVal e As EventArgs)
Handles MyBase.PreRender
        Session("plhmain") = plhmain
        Session("strResult") = strResult
        Session("counter") = counter
    End Sub
    Sub addbutton()
        btntest = New Button
        AddHandler btntest.Click, AddressOf updateresult
        btntest.ID = "BtnNumber" & counter
        btntest.Text = "Button #" & counter
        counter = counter + 1
        plhmain.Controls.Add(btntest)
        Dim spacer As LiteralControl = New LiteralControl("<br>")
        plhmain.Controls.Add(spacer)
        plhtest.Controls.Add(plhmain)
    End Sub
    Private Sub updateresult(ByVal sender As System.Object, ByVal e As
System.EventArgs)
        strResult = strResult & btntest.ID
        lblresult.Text = strResult
    End Sub

    Private Sub btnAddrow_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles btnAddrow.Click
        addbutton()
    End Sub
End Class

Thanks in advance

6 Apr 2006 8:27 PM

Cor Ligthert [MVP]

TB,

The buttons that you have created on your form dynamicly, do you need to
recreate again with any postback to be able to use them. I saw that not in
your code, maybe I missed it, however. If not, thatn you will in your case
probably have to do that using the counter you have already in the session..

I hope this helps,

Cor

6 Apr 2006 10:28 PM

TB

I think it has something to do with the naming of the dynamically
created controls becuase if I simplify it even further, simply creating
a page where ONE button is created dynamically ONCE and an event
handler is attached, then the event actually fires (once of course):

Content of dynamic.aspx

<%@ Page Language="vb" AutoEventWireup="false"
Codebehind="dynamic.aspx.vb" Inherits="testsite.dynamic"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <title>dynamic</title>
        <meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
        <meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
        <meta name="vs_defaultClientScript" content="JavaScript">
        <meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5">
    </HEAD>
    <body>
        <form id="Form1" method="post" runat="server">
            <asp:PlaceHolder ID="plh" Runat="server" /><br>
            <asp:Label ID="lblresult" Runat="server" />
        </form>
    </body>
</HTML>

content of dynamic.aspx.vb:

Public Class dynamic
    Inherits System.Web.UI.Page

Dim btntest As Button
    Dim strResult As String

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
        btntest = New Button
        AddHandler btntest.Click, AddressOf updateresult
        btntest.ID = "BtnNumber"
        btntest.Text = "Button #"
        plh.Controls.Add(btntest)

    End Sub
    Sub updateresult(ByVal sender As System.Object, ByVal e As
System.EventArgs)
        Dim spacer As LiteralControl = New LiteralControl("Hello<br>")
        plh.Controls.Add(spacer)
    End Sub
End Class

So why doesn´t it work when multiple controls are dynamically created
all with the same event handler??

TB