包含特定字段值的唯一共同约束

Question

对于我的一个模型，我需要确保某些行的unicity，但仅限于特定情况。只有“已验证”行应遵循此约束。在

基本上，我期待的是

class MyModel(models.Model):
    field_a = models.CharField()
    field_b = models.CharField()
    validated = models.BooleanField(default=False)

    class Meta:
        unique_together = (('field_a', 'field_b', 'validated=True'),)

Answer 1

除了前面的答案，您可以覆盖save()方法。应该是这样的：

def save(self, **kwargs):
    try:
        self.objects.get(field_a=self.field_a, field_b=self.field_b, validated=True)

        # The object already exist therefore throw an exception
        raise ValidationError(
            "field_a and field_b must be unique if validated=True"
        ) 

    except self.__class__.DoesNotExist:  # Save the model
        super(MyModel, self).save(**kwargs)  # inherit and call the save method

现在不需要调用clean()方法。在