Question

Hey Just wondering how the following can happen

Object reference not set to an instance of an object.

customerName.Text = Session(“userName”).ToString()

    If (Session("userId") Is Nothing) Then
        Response.Redirect(ConfigurationManager.AppSettings("site_base_url").ToString & "login/", False)
    End If

    customerName.Text = Session("userName").ToString()

Now I currently have no session set on this page. So the session is NULL but i am just wondering why my if statement is taking care of this problem, why does it even try to get to the next part i.e. Response.Write ?

Answer 1

From your code snippet it looks like the line Response.Write(Session("UID").ToString) will always be executed regardless of what happens with the if statement above it.

I wonder if the weird indentation isn’t confusing you. Try looking at it like this:

If (Session("userName") IsNot Nothing) Then
    customerName.Text = Session("userName").ToString()
End If

Response.Write(Session("UID").ToString)

Notice that I aligned the End If with the corresponding If above and the Response.Write... as well. The Response.Write... line clearly sits outside of the If block and since there is not return or break or continue in the If block it will always get executed.

And btw, it’s probably not the Session object that is null. You are calling ToString on an item you assume to be contained in the Session object. It’s more likely that the Session does not contain a “UID” entry.