Django，使用其他表格中的数据进行注释和排序

问题描述

在我的应用程序中，有些用户请求捐赠这些项目的项目和用户。我想获取最多捐款的所有用户。

In my app there are users who request items and users who donate those items. I would like to fetch all users that made the most donations.

这些是我的模型：

class ItemRequest(models.Model):
    item_type = models.ForeignKey(ItemType)
    description = models.CharField(max_length=1024, default='', blank=True)
    quantity = models.IntegerField()
    user = models.ForeignKey(User)
    completed = models.BooleanField(default=False)
    completed_dt = models.DateTimeField()


class Donation(models.Model):
    item_request = models.ForeignKey(ItemRequest, related_name='donation')
    user = models.ForeignKey(User, related_name='donor')
    quantity_offered = models.IntegerField(default=0)
    quantity_accepted = models.IntegerField(default=0)

更具体地说，我想以最完成的捐款（其中 item_request.completed = True）获取前5名捐助者。。我可以用一个查询来执行此操作吗？

More specifically, I would like to fetch the top-5 donors with the most "completed" donations (where item_request.completed=True). Can I do this with one query?

推荐答案

(User.objects
       .filter(donor__item_request__completed=True)
       .annotate(c=Count('donor'))
       .order_by('-c')[:5])

您应该可以命​​名您的 Donation.user.related_name 捐赠。

You should probably name your Donation.user.related_name donation too.

然后它将是

(User.objects
       .filter(donation__item_request__completed=True)
       .annotate(c=Count('donation'))
       .order_by('-c')[:5])

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