[英]How to make two foreign keys to same model unique together?
Let's say I have a relationship class such as: 假设我有一个关系类,例如:
class Friendship(models.Model):
person1 = models.ForeignKey(Person, related_name='person1')
person2 = models.ForeignKey(Person, related_name='person2')
so I want to make this object unique for a pair of Person
s. 所以我想使该对象对于一对
Person
是唯一的。 If I simply do unique_together = (("person1", "person2"),)
then I can end up with two Friendship
objects where 如果我只做
unique_together = (("person1", "person2"),)
那么我可以得到两个Friendship
对象,其中
FS1.person1 = A, FS1.person2 = B
FS2.person1 = B, FS2.person2 = A
I do not want this. 我不想这样。 I want a unique friendship object between two people.
我想要两个人之间一个独特的友谊对象。 So how can I ensure that there is -at most- one
Friendship
object for any pair of Person
s? 那么,如何确保任何一对
Person
最多有一个“ Friendship
对象?
Thanks ! 谢谢 !
I suggest you to use model.clean method: 我建议您使用model.clean方法:
class Friendship(models.Model):
person1 = models.ForeignKey(Person, related_name='person1')
person2 = models.ForeignKey(Person, related_name='person2')
def clean(self):
direct = FriendShip.objects.filter(person1 = self.person1, person2 = self.person2)
reverse = FriendShip.objects.filter(person1 = self.person2, person2 = self.person1)
if direct.exists() or reverse.exists():
raise ValidationError({'key':'Message')})
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