Django在相关模型中针对零记录的多对多查询

Question

使用标准Django示例模型进行M2M关系。我想返回一个没有Membership（即Membership表中没有相关记录）的Person（人）列表，我该如何去做这件事？有人能指出我的方向是否正确吗？

class Person(models.Model): 
    name = models.CharField(max_length=128) 

class Group(models.Model): 
    name = models.CharField(max_length=128) 
    members = models.ManyToManyField(Person, through='Membership') 

class Membership(models.Model): 
    person = models.ForeignKey(Person) 
    group = models.ForeignKey(Group) 
    date_joined = models.DateField() 
    invite_reason = models.CharField(max_length=64) 

谢谢。

Answer 1

Person.objects.filter(membership__isnull=True) 

https://docs.djangoproject.com/en/1.4/ref/models/querysets/#isnull