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Django多对多关系,并通过

many-to-many foreign-keys django python

Jiaaro · 技术社区 · 15 年前

我要存储哪个用户邀请了另一个用户加入组…但Django告诉我这是矛盾的,违反了规则(这是有道理的)。

groups.group:中介模型组成员有多个用户的外键,即不明确,不允许。

那么,我如何正确地做到这一点呢?可能是一般关系?可能有效,但似乎有点复杂…以下是我接近它的方式(去掉无关的部分)

from django.contrib.auth.models import User

class UserGroup(models.Model):
    members = models.ManyToManyField(User, through='Group_to_Member')

class UserGroup_to_Member(models.Model):
    group = models.ForeignKey(UserGroup)
    member = models.ForeignKey(User)

    invited_by = models.ForeignKey(User, related_name="group_invited_users")

解决方案

好吧,所以我把你们提供的答案结合了一下(谢谢!)我在互联网上发现的东西加上我自己承认的微不足道的Python Fu:

from django.contrib.auth.models import User

class UserGroup(models.Model):
    # notice there is no member object here
    ... other model data

    def add_member(self, **kwargs):
        g2m = UserGroup_to_Member(group = self,  **kwargs)
        g2m.save()

    def remove_member(self, member):
        g2m = UserGroup_to_Member.objects.get(group=self, member=member)
        g2m.delete()

    # This is not elegant at all, help please? I'm pretty sure it isn't
    # as bad on the database as it looks though.
    def get_members(self):
        g2ms = UserGroup_to_Member.objects.filter(group=self)
        member_ids = [g2m.member.id for g2m in g2ms]
        members = User.objects.none()
        for id in member_ids:
            members = members | User.objects.get(id=id)
        return members

class UserGroup_to_Member(models.Model):
    group = models.ForeignKey(UserGroup)
    member = models.ForeignKey(User)

    invited_by = models.ForeignKey(User, related_name="group_invited_users")

2 回复 | 直到 15 年前

Graham King ptim 15 年前

你必须自己管理它:

class MyGroup(models.Model):
    name = models.CharField(max_length=100)

class Membership(models.Model):
    group = models.ForeignKey(MyGroup)
    member = models.ForeignKey(User)

    invited_by = models.ForeignKey(User, related_name='invited_set')

那么,而不是 group.members.all() 你做 group.membership_set.all() .

另外,我不会使用“group”作为模型名,因为django已经有了一个group对象。

Mauricio Abreu 10 年前

如果您使用的是Django 1.7,这是可能的。

来自文档: https://docs.djangoproject.com/en/1.7/topics/db/models/#extra-fields-on-many-to-many-relationships

在Django 1.6及更早版本中,中间模型包含超过多对多模型中涉及的任何模型的一个外键以前是禁止的关系。