title: NHibernate Guid generator if new
body: <p>I'd like NHibernate to generate guids for entities only if they are not set manually by the user or application. Basically, when saving objects with new Guid() (all zeros), NHibernate should generate one. When saving an object that has a non-zero Guid, it should use that instead.</p>
  
  <p>Is my only option to write my own generator?</p>
  
  <p><strong>edit</strong> Folks, I'm aware of 'assigned'. I should have specified I was aware of it. Since it doesn't do what I want it to do, it's not the option I'm looking for. Writing my own generator is an option that works, but I'd like something else. I'm suspecting there is nothing else.</p>