The last error check of the _parse function checks that there is a positive value. Is it possible to make the check optional? Reason being is I have a search form with multiple fields. Each one of those fields are separately ran through Search::QueryParser. So if I wanted to find all books by rowling that were not Harry Potter books, I could enter rowling in the author field and -"harry potter" in the title field. If I comment out the positive value check, everything works as expected.