Django独特的外键组合

Question

I have 4 django models:

class KeyOne(models.Model):
    name = models.CharField(unique=True)

class KeyTwo(models.Model):
    name = models.CharField(unique=True)

class KeyThree(models.Model):
    name = models.CharField(unique=True)

class KeyList(models.Model):
    key_one = models.ForeignKey(KeyOne)
    key_two = models.ForeignKey(KeyTwo)
    key_three = models.ForeignKey(KeyThree)
    list = models.CharField()

Basically, KeyList is a list of keywords associated with different combinations of KeyOne , KeyTwo and KeyThree . How do I make sure that, in the Django Admin, only unique combos can be entered?

Answer 1

You have to set in the Meta class in the KeyList:

class KeyList(models.Model):
    key_one = models.ForeignKey(KeyOne)
    key_two = models.ForeignKey(KeyTwo)
    key_three = models.ForeignKey(KeyThree)
    list = models.CharField()
    class Meta:
        unique_together = (("key_one", "key_two", "key_three"),)

Answer 2

Django > 2.2

Django Documentation says :

Use UniqueConstraint with the constraints option instead. UniqueConstraint provides more functionality than unique_together. unique_together may be deprecated in the future.

So in your case:

class KeyList(models.Model):
    key_one = models.ForeignKey(KeyOne)
    key_two = models.ForeignKey(KeyTwo)
    key_three = models.ForeignKey(KeyThree)
    list = models.CharField()
    class Meta:
        constraints = [
            models.UniqueConstraint(fields=["key_one", "key_two", "key_three"], name="all_keys_unique_together")
]