Question

I’m having problem regarding session items. Before I use them, I want to check if they exists, but using this codes gives me error:

If (Session("SomeSessionItem") Is Nothing) Then
...
End If

This is the error:

Object reference not set to an instance of an object.

I think Session("SomeSessionItem") tries to acquire the value of the session item. If the item doesn’t exists then it throws exception. But how do I check if a session item exists before using them?

• I have a page Home.aspx.
• In the Home.aspx.vb, I instantiate a WebUserControl SomeControl.ascx. Note that in Home.aspx.vb event handler Page_Load I can use a condition to check session without getting an exception.
• Inside SomeControl.ascx.vb I’m trying to access the session, here’s where the exception occurs.

Answer 1

Does that work for you?

If (Session IsNot Nothing)
    Dim item as Object = Session("SomeSessionItem")
    If (item IsNot Nothing)
    ...
    End If
End If

Also, you may need to check HttpContext.Current.Session rather than simply Session if you’re seeing the the following error:

Session does not exist in this context