django如何与外键聚合工作？

Question

我有一个模特：

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)
    age = models.IntegerField()

class Publisher(models.Model):
    name = models.CharField(max_length=300)
    num_awards = models.IntegerField()

class Book(models.Model):
    name = models.CharField(max_length=300)
    pages = models.IntegerField()
    price = models.DecimalField(max_digits=10, decimal_places=2)
    rating = models.FloatField()
    authors = models.ManyToManyField(Author)
    publisher = models.ForeignKey(Publisher)
    pubdate = models.DateField()

class Store(models.Model):
    name = models.CharField(max_length=300)
    books = models.ManyToManyField(Book)
    registered_users = models.PositiveIntegerField()

我无法理解以下代码的工作原理

这是来自django官方文档，在备忘单中。 https://docs.djangoproject.com/en/1.10/topics/db/aggregation/

我要做的是计算以下型号的总票数 我在文档中使用Question.objects.filter(owner_id=1).annotate(total_votes=Sum('votes'))。但这不适合我。

class Question(models.Model):
    question_text = models.CharField('Question',max_length=200)
    pub_date = models.DateTimeField('date published')
    owner = models.ForeignKey(User,default=DEFAULT_USER_ID)

class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

Answer 1

您的问题模型没有您的选择模型所做的投票

Question.objects.filter(owner_id=1).annotate(total_votes=Sum('choice__votes'))