Command event for dynamically created linkbuttons not firing

[Hamayun Khan]

Hi I have created linkbuttons dynamically using the below code

Sub createlinkbutton(ByVal commandtext As String, ByVal Cmdarg As String, ByVal pane As Panel, ByVal count As Int32)
 
Dim i = 0
 
Dim panel1 As Panel = New Panel
 
panel1.CssClass = "boxx"
 
pane.Controls.Add(panel1)
 
Dim lbButton As LinkButton = New LinkButton
 
lbButton.Text = commandtext
 
lbButton.CommandName = commandtext
 
lbButton.CommandArgument = Cmdarg
 
AddHandler lbButton.Command, AddressOf Me.LinkButton_Command
 
panel1.Controls.Add(lbButton)
 
End Sub
 
 
 
Protected Sub LinkButton_Command(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.CommandEventArgs)
 
If e.CommandArgument.ToString = "Region" Then
 
Session("Region") = e.CommandName
 
End If
 
If e.CommandArgument.ToString = "LEA" Then
 
Session("LEA") = e.CommandName
 
End If
 
If e.CommandArgument.ToString = "Subject" Then
 
Session("Subject") = e.CommandName
 
End If
 
If e.CommandArgument.ToString = "Position" Then
 
Session("Position") = e.CommandName
 
End If
 
If e.CommandArgument.ToString = "SchoolPhase" Then
 
Session("SchoolPhase") = e.CommandName
 
End If
 
Response.Write("<script language=""javascript"">alert(""" & Session("Region") & """)</script>")
 
populate()
 
End Sub

Linkbuttons are successfully generated. When i click one of the linkbutton. The command event doesn't fired. While I have Add command event handler to the linkbuttons.

What is wrong in my code

Thanks

[Frinavale]

Where are you calling your "createlinkbutt on" method?
In the Page Init event?

If not then your event will never fire. The link button will post back to the server, but the server will not load the ViewState of the link button, and so the event for the link button will not be loaded...theref ore it will not fire.

-Frinny

[Hamayun Khan]

@Frinavale
Thanks for your reply.

But The problem is very strange. Please look into code problem once again.

Function to generate linkbuttons.

Sub createlinkbutton(ByVal commandtext As String, ByVal Cmdarg As String, ByVal pane As Panel, ByVal count As Int32)
        Dim panela As Panel = New Panel
        panela.CssClass = "boxx"
        pane.Controls.Add(panela)
        Dim lbButton As LinkButton = New LinkButton
        lbButton.Text = commandtext
        lbButton.CommandName = commandtext
        lbButton.CommandArgument = Cmdarg
        AddHandler lbButton.Command, AddressOf Me.LinkButton_Command
        AddHandler lbButton.Click, AddressOf Me.LinkButton_Click
        panela.Controls.Add(lbButton)
    End Sub
 

And the command event is

 Protected Sub LinkButton_Command(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.CommandEventArgs)
        If e.CommandArgument.ToString = "Region" Then
            Session("Region") = e.CommandName
        End If
        If e.CommandArgument.ToString = "LEA" Then
            Session("LEA") = e.CommandName
        End If
        If e.CommandArgument.ToString = "Subject" Then
            Session("Subject") = e.CommandName
        End If
        If e.CommandArgument.ToString = "Position" Then
            Session("Position") = e.CommandName
        End If
        If e.CommandArgument.ToString = "SchoolPhase" Then
            Session("SchoolPhase") = e.CommandName
        End If
        Response.Write("<script language=""javascript"">alert(""" & Session("Region") & """)</script>")
        populate()
        Response.Write("<script language='javascript'>alert('hello')</script>")
    End Sub
 

Another funciton for some other functionality

Public Sub loadRegion()
For k = 0 To DT.Rows.Count
      createlinkbutton(DT.Rows(k)("Region"), DT.Rows(k)("BtnArg"), Pane1, DT.Rows(k)("num"))
Next
 
        'createlinkbutton("London", "Region", Pane, 12)
        'createlinkbutton("aLondon", "Region", Pane, 12)
        'createlinkbutton("Lsondon", "Region", Pane, 12)
        'createlinkbutton("Lodndon", "Region", Pane, 12)
        'createlinkbutton("Londdon", "Region", Pane, 12)
        'createlinkbutton("Londfon", "Region", Pane, 12)
        'createlinkbutton("Londofn", "Region", Pane, 12)
        'createlinkbutton("fLondon", "Region", Pane, 12)
        'createlinkbutton("Lcondon", "Region", Pane, 12)
        'createlinkbutton("Lovndon", "Region", Pane, 12)
        'createlinkbutton("Lon don", "Region", Pane, 12)
        'createlinkbutton("Loncdon", "Region", Pane1, 12)
        'createlinkbutton("Loncdon", "Region", Pane1, 12)
        'createlinkbutton("Londxon", "Region", Pane1, 12)
        'createlinkbutton("Londosn", "Region", Pane1, 12)
        'createlinkbutton("Londons", "Region", Pane1, 12)
        'createlinkbutton("kLondon", "Region", Pane1, 12)
        'createlinkbutton("Ljondon", "Region", Pane, 12)
        'createlinkbutton("Lonndon", "Region", Pane, 12)
        'createlinkbutton("Lonndon", "Region", Pane, 12)
        'createlinkbutton("Londnon", "Region", Pane1, 12)
        'createlinkbutton("Londonn", "Region", Pane1, 12)
End Sub
 

Now if I call the LoadRegion function from any where the button generated don't fires the command event. If i comment the For loop portion and uncomment the
commented portion then the button generated works fine. i.e when i click one of the button command event fires successfully.

Instead of using if i use while loop buttons are created successfully but event doesn't work.

This is very urgent.
Waiting for quick reply.

[Frinavale]

Is DT.Rows.Count = 0?
Does your loop actually happen?
Have you tried stepping through this?

You never answered my original question.
Are you calling this in your Page Init event?

[Hamayun Khan]

@Frinavale
NO DT.Rows.Count is not equals 0 but the loop happen successfully.

And I m calling this from page load event.

Thanks

[Frinavale]

Move it to the Page Init event.
For more information on why please see this article on how to use dynamic controls in asp.net.

[Hamayun Khan]

@Frinavale

Thanks

If from the page load event I call to button create function like below then the command event works fine.

 
createlinkbutton("Londosn", "Region", Pane1, 12) 
 
 

but if i place the same code in for or while loop then the command event doesn't work.

e.g

for i=1 to 5
createlinkbutton("Londosn", "Region", Pane1, 12) 
Next
 

Here the command event does not work.

[Frinavale]

Well,one obvious thing is that you are creating a button with the command name and text "Londosn" in Panel 1, five times.

for i=1 to 5
createlinkbutton("Londosn", "Region", Pane1, 12) 
Next
 

Have you considered providing unique values (like you do by hand when you aren't looping) to see if it works?

For example:

for i=1 to 5
createlinkbutton("Londosn_"+i.ToString, "Region", Pane1, 12) 
Next
 

[Hamayun Khan]

@Frinavale

Thanks for Reply. I have done the job little different.

<asp:DataList ID="DataList2" runat="server" DataSourceID="SqlDataSource1" RepeatDirection="horizontal"
                    RepeatLayout="Flow">
                    <ItemTemplate>
                        <asp:LinkButton OnCommand="Command"  CommandName="Region" CommandArgument='<%# Eval("Region") %>' runat="server"><%# Eval("Region") %></asp:LinkButton>                        
                        |
                    </ItemTemplate>
                </asp:DataList>
                <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:dbase_DataConnectionString6 %>"
                    SelectCommand="SELECT  [Region] FROM [tblregion]"></asp:SqlDataSource>
 

It is now working fine. thanks.