SortableModel save method improvement

[Adilkhanweb]

Current code

    @staticmethod
    def get_max_sort_order(qs):
        existing_max = qs.aggregate(Max("sort_order"))
        existing_max = existing_max.get("sort_order__max")
        return existing_max

    def save(self, *args, **kwargs):
        if self.pk is None:
            qs = self.get_ordering_queryset()
            existing_max = self.get_max_sort_order(qs)
            self.sort_order = 0 if existing_max is None else existing_max + 1
        super().save(*args, **kwargs)

Improved code

    def save(self, *args, **kwargs):
        if self._state.adding:
            existing_max = self.__class__.objects.aggregate(Max('sort_order'))
            existing_max = existing_max['sort_order__max']
            self.order = 0 if existing_max is None else existing_max + 1
        super().save(*args, **kwargs)