dfde30ba962305f6877e61ce256bbe54d6a785aa,ratings/models.py,,post_delete_rating,#,49

Before Change

    try:
        with transaction.atomic():
            instance.sound.num_ratings = F("num_ratings") - 1
            rating = SoundRating.objects.filter(
                    sound_id=instance.sound_id).aggregate(Avg("rating")).values()[0]
            if not rating:
                rating = 0
            instance.sound.avg_rating = rating
            instance.sound.save()

After Change

    try:
        with transaction.atomic():
            instance.sound.num_ratings = F("num_ratings") - 1
            avg_rating = SoundRating.objects.filter(
                    sound_id=instance.sound_id).aggregate(average_rating=Coalesce(Avg("rating"), 0))
            rating = avg_rating["average_rating"]
            instance.sound.avg_rating = rating
            instance.sound.save()
    except ObjectDoesNotExist:
        pass

Instances