In ASP.NET, if you try to use a session or request variable before it has been set, you’ll get an error. The following functions prevent this by checking for nothing and returning a null string if this is true.

Public Shared Function zGetSessionValue(ByVal se As HttpSessionState, ByVal keyItem As String) As String   'this proc avoids an error if the session variable has not been set   Dim res As String = ""   if se(keyItem) <> Nothing Then      res = se(keyItem)   End If   Return resEnd Function Public Shared Function zGetRequestValue(ByVal re As HttpRequest, ByVal keyItem As String) As String   'this proc avoids an error if the request variable has not been set  Dim res As String = ""  If re(keyItem)  Nothing Then    res = re(keyItem)  End If  Return resEnd Function'Usage --------------------------------------Dim SVal as String'if Session("MyVarName") has not been set SVal will be ""SVal = zGetSessionValue(Session, "MyVarName")Dim RVal as String'if Request("MyVarName") has not been set RVal will be ""RVal = zGetRequestValue(Request, "MyVarName")