python - 如何在 django 中编写带有过滤器和按条件排序的连接三个表的查询

Question

我有三个模型:

class Category(models.Model):
    category_name = models.CharField(max_length=128, unique=True)
    category_alias = models.CharField(max_length=128, unique=True)
    category_desc = models.TextField()

class Question(models.Model):
    user = models.ForeignKey(User)
    category = models.ForeignKey(Category)
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField(auto_now=True)
    is_approved = models.BooleanField(default=0)

class Answer(models.Model):
    user = models.ForeignKey(User)
    question = models.ForeignKey(Question)
    answer = models.TextField()
    is_approved = models.BooleanField(default=0)

class Rating(models.Model):
    user = models.ForeignKey(User)
    answer = models.ForeignKey(Answer)
    rating = models.BooleanField(default=0)

我需要一个查询，该查询将找到最喜欢的答案(具有最高评级的答案)及其问题和特定类别的评级。这意味着如果答案 2 的评分最高，那么我将获得该答案的对象以及相关问题和任何特定类别的评分。

Answer 1

class Rating(models.Model):
    user = models.ForeignKey(User)
    answer = models.ForeignKey(Answer)
    rating = models.BooleanField(default=0, related_name='rating')


answers = Answer.objects.filter(question__category__id=category_id).annotate(
    rating_sum=Count(rating__rating)).order_by('-rating_sum')

您应该使用“注释”方法来计算正分并按此字段排列答案。