Django在相關模型中針對零記錄的多對多查詢

Question

使用標準Django示例模型進行M2M關係。我想返回一個沒有Membership（即Membership表中沒有相關記錄）的Person（人）列表，我該如何去做這件事？有人能指出我的方向是否正確嗎？

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) 

謝謝。

Answer 1

Person.objects.filter(membership__isnull=True) 

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