title: In a django model custom save() method, how should you identify a new object?
body: <p>I want to trigger a special action in the save() method of a Django model object when I'm saving a new record (not updating an existing record.)</p>
  
  <p>Is the check for (self.id != None) necessary and sufficient to guarantee the self record is new and not being updated?  Any special cases this might overlook?</p>