Question

I’m trying to test if an object is nothing before I get it’s value, but I get an error “NullReferenceException”

happens on the first line here：

If Not ORInvoiceLineRet.InvoiceLineRet.ItemRef.FullName Is Nothing Then
    li.FullName = ORInvoiceLineRet.InvoiceLineRet.ItemRef.FullName.GetValue()
End If

System.NullReferenceException
{“Object reference not set to an instance of an object.”}

How can I test for this, without just handling the error in a try/catch?

Answer 1

There are more objects involved that can be nothing:

• ORInvoiceLineRet can be nothing
• ORInvoiceLineRet.InvoiceLineRet can be nothing
• ORInvoiceLineRet.InvoiceLineRet.ItemRef can be nothing
• ORInvoiceLineRet.InvoiceLineRet.ItemRef.FullName can be nothing

So the only safe way here is:

If ORInvoiceLineRet IsNot Nothing _
   AndAlso ORInvoiceLineRet.InvoiceLineRet IsNot Nothing _
   AndAlso ORInvoiceLineRet.InvoiceLineRet.ItemRef IsNot Nothing _
   AndAlso ORInvoiceLineRet.InvoiceLineRet.ItemRef.FullName IsNot Nothing  Then
    li.FullName = ORInvoiceLineRet.InvoiceLineRet.ItemRef.FullName.GetValue()
End If