聚合Django中子查询的带注释字段

from django.db.models import Count, Sum
from django.db.models.expressions import Subquery, OuterRef

# 假设有两个模型，一个是文章模型，一个是评论模型
class Article(models.Model):
    title = models.CharField(max_length=100)
    # ...

class Comment(models.Model):
    article = models.ForeignKey(Article, on_delete=models.CASCADE)
    content = models.TextField()
    # ...

# 查询每篇文章的评论数量，并将评论数量作为注释字段添加到查询结果中
articles = Article.objects.annotate(comment_count=Count('comment'))

# 查询每篇文章的评论总字数，并将总字数作为注释字段添加到查询结果中
articles = Article.objects.annotate(total_words=Sum('comment__content__length'))

# 查询每篇文章的最新评论内容，并将最新评论内容作为注释字段添加到查询结果中
latest_comments = Comment.objects.filter(article=OuterRef('pk')).order_by('-created_at')
articles = Article.objects.annotate(latest_comment=Subquery(latest_comments.values('content')[:1]))

# 使用注释字段进行过滤
articles = Article.objects.annotate(comment_count=Count('comment')).filter(comment_count__gt=10)