code: def active(self):
          
          qs = self.get_queryset()
          return qs.filter(
              models.Q(
                  models.Q(start_date__isnull=True) |
                  models.Q(start_date__lte=now().date())
              ) &
              models.Q(
                  models.Q(end_date__isnull=True) |
                  models.Q(end_date__gte=now().date())
              )
          ).distinct()
docs: Returns all outlets that are currently active and have sales.