code: def _update(self, commit=False):
          
          votes = Vote.objects.filter(
              content_type    = self.get_content_type(),
              object_id       = self.instance.pk,
              key             = self.field.key,
          )
          obj_score = sum([v.score for v in votes])
          obj_votes = len(votes)
  
          score, created = Score.objects.get_or_create(
              content_type    = self.get_content_type(),
              object_id       = self.instance.pk,
              key             = self.field.key,
              defaults        = dict(
                  score       = obj_score,
                  votes       = obj_votes,
              )
          )
          if not created:
              score.score = obj_score
              score.votes = obj_votes
              score.save()
          self.score = obj_score
          self.votes = obj_votes
          if commit:
              self.instance.save()
docs: Forces an update of this rating (useful for when Vote objects are removed).