python - Django 的 NotImplementedError : aggregate() + distinct(fields) not implemented

Question

我有非常简单的模型:

class Profile(models.Model):
    name = models.CharField(max_length=100, unique=True)
    age = models.IntegerField(default=18)


class Place(models.Model):
    name = models.CharField(max_length=100, blank=True, null=True)
    address = models.CharField(max_length=100, blank=True, null=True)


class ProfilePlaceFeedback(models.Model):
    profile = models.ForeignKey(Profile, on_delete=models.CASCADE, related_name='feedback_set')
    place = models.ForeignKey(Place, on_delete=models.CASCADE, related_name='feedback_set')
    review = models.TextField(blank=True, null=True)
    rating = models.IntegerField(default=0)
    timestamp = models.DateTimeField(auto_now_add=True)

ProfilePlaceFeedback - 是用于存储用户留下的每个评分的模型。为了计算某些地点 的评分，我需要检索所有最新 用户反馈并对所有评分值求和。下面是检索每个用户的所有最后反馈的代码:

place.feedback_set.order_by('profile', '-timestamp').distinct('profile')

但是进行查询:

place.feedback_set.order_by('profile', '-timestamp').distinct('profile').aggregate(Sum(rating))

引发异常:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/PATH_TO_VIRTUALENV/lib/python3.6/site-packages/django/db/models/query.py", line 357, in aggregate
    raise NotImplementedError("aggregate() + distinct(fields) not implemented.")
NotImplementedError: aggregate() + distinct(fields) not implemented.

使用 Django 2.0 和 postgresql 作为数据库。

请帮我解决这个问题:)

Answer 1

看来你需要这个或类似的东西:

place.feedback_set.values('profile').annotate(rating_sum=Sum(rating)).values('profile','rating_sum').order_by('profile')