Issue in VS 2005 ASP.Net Web App referencing controls between clas

microsoft.public.dotnet.framework.aspnet.webcontrols

24 Mar 2009 3:34 AM

George Kenyon

Hi,

I am rewriting a Windows Application which has many vb classes containing
code which references controls such as Label which are defined in the class
where the form design is, also the code in the other classes dynamically add
or change properties of controls in the design class.

When I try to duplicate this in my ASP.Net 2 Web Application in Visual
Studio 2005 the Web Page controls such as Label are not accessible in the
other classes and a NullReferenceError occurs at run time.

I have created a test project with two classes in the same page code behind
and the string MyString in the page class is available in the other class but
the Label Label1 isn't and gets the NullReferenceError.

This is the code in the test project:

Public Class DefaultMine
    Inherits System.Web.UI.Page
    Public MyString As String = "This is the base class string."
    Public Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
    End Sub
    Public Sub Button1_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Button1.Click
        Dim ac As New AnotherClass
        Label1.Text = "Label test in Button Click"
        ac.TestSub()
    End Sub
End Class

Public Class AnotherClass : Inherits DefaultMine
    Public Sub TestSub()
        MyBase.MyString = "String test in Class AnotherClass"
        MyBase.Label1.Text = "Label test in Class AnotherClass"
    End Sub
End Class

The designer.vb declaration for the label is:

Public WithEvents Label1 As Global.System.Web.UI.WebControls.Label

When I step through the program the AnotherClass Class code sees the value
of the string MyString declared in the page class and changes to the new
value but the Label comes in in with no value and gets the error.

Does anyone know how to resolve this because I have tried everything I can
think of and looked in many forums for a solution.

Your help would be much appreciated.

--
George