定义 Django 模型约束

Question

我想将约束添加到涉及对另一个模型对象的引用的模型上。在下面的代码中，我希望在 ProjectMember 模型上， project_member 字段被限制为与项目模型中的 project_creator 不同。class User(models.Model):  fullname = models.CharField(max_length=200)  email = models.EmailField(max_length=254)  password = models.CharField(max_length=254)class Project(models.Model):  name = models.CharField(max_length=200)  timestamp = models.DateTimeField("date created", auto_now=True)  project_creator = models.ForeignKey(User, on_delete=models.CASCADE)class ProjectMember(models.Model):  project = models.ForeignKey(Project, on_delete=models.CASCADE)  project_member = models.ForeignKey(      User,      on_delete=models.CASCADE,      verbose_name="member of the project"  )  class Meta:      order_with_respect_to = 'user_member'      constraints = [          models.CheckConstraint(check= ,              name='project creator not project member'),      ]

Answer 1

您可以像这样将它添加到 Q 对象中，

class Meta:

  order_with_respect_to = 'user_member'

  constraints = [

      models.CheckConstraint(check=~Q(project_member_id=project__project_creator_id) , 

         name='project creator not project member'),

  ]

希望这可以帮助！