Question

我想按平均评分对所有故事进行排序，当我输入url ... / stories？ordering = average_rating时，会出现错误：'list' object has no attribute 'model'

    def get_queryset(self):
        queryset = Story.objects.all()
        ordering = self.request.query_params.get('ordering', None)
        if ordering == 'average_rating':
            return sorted(queryset, key=lambda s: s.average_rating)
        return queryset

class Story(models.Model):
    ...
    @property
    def average_rating(self):
        average_rating = self.ratings.all().aggregate(Avg('rating'))['rating__avg']
        if average_rating is not None:
            return round(float(average_rating), 2)

        return None

Answer 1

sorted(queryset, key=lambda s: s.average_rating)将返回一个列表，而get_queryset应返回一个queryset

您可以尝试以下操作：

def get_queryset(self):
    queryset = Story.objects.all()
    ordering = self.request.query_params.get('ordering', None)
    if ordering == 'average_rating':
        return queryset.annotate(rating_avg=Avg('ratings__rating')).order_by('rating_avg')
    return queryset

Answer 2

顾名思义，get_queryset需要返回查询集而不是列表。

幸运的是，您可以在数据库中完成整个查询和排序；您不需要average_rating方法。

    queryset = Story.objects.annotate(average_rating= Avg('ratings__rating'))
    ordering = self.request.query_params.get('ordering', None)
    if ordering == 'average_rating':
        queryset = queryset.order_by("average_rating")
    return queryset

“列表”对象没有属性“模型”

2 个答案: