django - 获取一个表中没有外键的所有对象

I have 2 models:

我有2个型号:

class Friend(models.Model):
    person1 = models.ForeignKey("Person", related_name="friend1")
    person2 = models.ForeignKey("Person", related_name="friend2")
    created = models.DateTimeField(auto_now=True, auto_now_add=True, editable=False)

class Person(models.Model):
    firstname = models.CharField(max_length=100)
    surname = models.CharField(max_length=100)
    created = models.DateTimeField(auto_now=True, auto_now_add=True, editable=False)
class Friend(model