Updating an old module originally designed for ASP.NET 2 the test IsNullOrEmpty gave the error IsNullOrEmpty.
The string test used was
If Not String.IsNullOrEmpty(filterString) Then
...
End if
And the error viewed was:
'IsNullOrEmpty' is not a member of 'String'
An alternative to this test is to test for nothing, together with a test to ensure that the string had a length.
In the example below filterString is the string to be tested.
If not filterString is nothing andalso filterString.Length > 0 then
...
End if
