如何使用Django的ORM进行过滤聚合

I have a Django model like:

我有一个Django模型

class Post(models.Model):

    name = models.CharField(max_length=10)

class Topic(models.Model):

    name = models.CharField(max_length=10)

class Annotator(models.Model):

    post = models.ForeignKey(Post, related_name='annotations')

    topic = models.ForeignKey(Topic)

    name = models.CharField(max_length=10)
cl