Question

My vb.net application needs to use a session variable. I don’t really know how to use it in ASP.net. I’ve been trying to use what my books have, but I can’t get this label to work. I need the user input to be validated against the database and if their code is in the database, the textbox should disappear and a label will appear saying Welcome.

The way I wrote it, I get an error saying the server tag is not well formed and in the codebehind it says that the ID of my label is not declared. Can anyone spot any problems with the code I wrote?

<asp:Label ID="lblIB" runat="server" DataSourceID="dsIBs" 
Text="Welcome, <%# Eval("First_Name") %> '&' <%# Eval("Last_Name")%>">
</asp:Label>


Protected Sub CustomValidator1_ServerValidate(ByVal source As Object, ByVal 
  args As System.Web.UI.WebControls.ServerValidateEventArgs) Handles
  CustomValidator1.ServerValidate
    args.IsValid = True
    For Each drv As DataRowView In dsIBs.[Select](DataSourceSelectArguments.Empty)
        If drv("baccount").ToString() = args.Value Then
            args.IsValid = False
            lblIB.Visible = False
            Exit For
        End If
    Next

    If args.IsValid Then
        IBTextBox.Visible = False
        IBTextBoxButton.Visible = False
        lblIB.Visible = True
    End If
End Sub

UPDATE:

<asp:Label ID="lblIB" runat="server" Text=""></asp:Label>

    Protected Sub CustomValidator1_ServerValidate(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs) Handles CustomValidator1.ServerValidate
    args.IsValid = True
    For Each drv As DataRowView In dsIBs.[Select](DataSourceSelectArguments.Empty)
        If drv("baccount").ToString() = args.Value Then
            args.IsValid = False
            lblIB.Visible = False
            Exit For
        End If
    Next

    If args.IsValid Then
        IBTextBox.Visible = False
        IBTextBoxButton.Visible = False
        lblIB.Visible = True
        lblIB.Text = String.Format("Welcome, {0} {1}", Session("FirstName"), Session("LastName"))

    End If
End Sub

UPDATE 2:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) 
Handles Me.Load
    lblIB.Visible = False
End Sub


If args.IsValid Then
   IBTextBox.Visible = False
   IBTextBoxButton.Visible = False
   lblIB.Visible = True
   lblIB.Text = String.Format("Welcome, {0} {1}", Session("FirstName"),
   Session("LastName"))

    Protected Sub IBTextBoxButton_Click(ByVal sender As Object, ByVal e As 
    System.EventArgs) Handles IBTextBoxButton.Click
    Session("IB") = IBTextBox.Text
    Dim IB As String = Session("IB")
    Response.Redirect(Request.RawUrl + "&IB=" + Session("IB"))
End Sub

Answer 1

Your markup is wrong because the Label control doesn’t have a DataSourceID property, so you should remove it:

<asp:Label ID="lblIB" runat="server" 
Text="Welcome, <%# Eval("First_Name") %> '&' <%# Eval("Last_Name")%>">
</asp:Label>

I would also remove the Eval expression (unless it’s inside a databound control -gridview, etc-) in the Text property and leave it as:

<asp:Label ID="lblIB" runat="server" 
Text="">
</asp:Label>

Finally, you should be able to perform your validation on the server side and set the Text programmatically doing something like:

lblIB.Text = "Welcome " + First_Name + " " + Last_Name

Where First_Name and Last_Name are read from the database somehow.