Django注释和过滤器

Question

如何查询满足谓词的相关模型的数量？假设我有一个模型

class Comment(Model):
    text = CharField(max_length=100)
    parent = ForeignKey('Comment')
    created_at = DateTimeField()

我希望选择所有评论，其中包含在特定日期之后创建的子评论数。等同于SQL的东西

select c1.*, count(c2.*) from comments c1 
left join comments c2 on c1.id = c2.parent_id and c2.created_at > the_date
group by c1.*

有没有办法使用QuerySet？

Answer 1

Comment.objects.filter(comment__created_at__gte=the_date).annotate(Count('comment'))