Django复合在多个模型字段上是唯一的 [英] Django composite unique on multiple model fields

问题描述

让我们说我有一个社交网络帖子，用户和喜欢的模型:

Let us say I have a model for social network posts, users and likes:

class Post(models.Model):
    submitter = models.ForeignKey(User, null=False, default=None)
    content = models.CharField()
    date = models.DateField()

    with_likes = PostLikeCountManager()
    objects = models.Manager()

class Like(models.Model):
    user = models.ForeignKey(User)
    post = models.ForeignKey(Post)
    time = models.DateTimeField(auto_now_add=True)

将 Post 模型视为代表 Facebook 帖子是很有帮助的.现在，我想限制每个用户每条帖子的赞数.我该如何实现?一种方法是在 Like 类的( user ， post )属性上创建一个复合主键.我不知道如何在Django中实现这一目标.另一种方法是同时对两个属性使用 unique = True .有可能吗?

It would be helpful to think of Post model as representing a Facebook post. Now, I would like to limit one like per post per user. How do I achieve that? One way would be to create a composite primary key on (user, post) attributes of Like class. I don't know how to achieve that in Django. The other would be to use unique=True on two attributes simultaneously. Is that possible?

谢谢.

推荐答案

是的，请使用唯一在一起:

class Like(models.Model):
    user = models.ForeignKey(User)
    post = models.ForeignKey(Post)
    time = models.DateTimeField(auto_now_add=True)

    class Meta:
        unique_together = ('user', 'post')

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