Question

假设我有User，Newsletter和Subscription模型，Subscription是User和Newsletter的映射表，例如。订阅具有用户和简报的外键

class User(models.Model):
  ...

class Newsletter(models.Model):
  ...

class Subscription(models.Model):
  subscriber = models.ForeignKey(User)
  newsletter = models.ForeignKey(Newsletter)

如何获取返回特定用户在非常简单的查询中订阅的新闻稿的查询集？我觉得有一个，但除非通过多个陈述来实现这一点，否则无法真正想到它。

Answer 1

这应该有效：

Newsletter.objects.filter(
    id__in=[subscription.newsletter.id for subscription in
            Subscription.objects.filter(subscriber=user)]

更易阅读（和详细）版本：

subscriptions = Subscription.objects.filter(subscriber=user) # all subscriptions for a given user

newsletter_ids = [subscription.newsletter.id for subscription in subscriptions]

Newsletter.objects.filter(id__in=newsletter_ids) # answer

django模型manytomany过滤器

1 个答案: