最近写公司的业务代码, 碰到这么一个问题:
一个User对应多个Account, 而每个Account又可以分享给多个user, 典型的多对多的关系.
但问题在于每个关系, 都有一个permissionsharing的属性: 0: 只读 / 1: 读写 / 2: 自身创建.
晚上我尝试着用django的orm来实现这个需求.
Model的定义:
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| from django.db import models
from django.db import models
class Account(models.Model):
name = models.CharField(max_length=128)
def __str__(self):
return self.name
class User(models.Model):
name = models.CharField(max_length=128)
accounts = models.ManyToManyField(Account, through='PermissionSharing')
def __str__(self):
return self.name
class PermissionSharing(models.Model):
account = models.ForeignKey(Account, on_delete=models.CASCADE)
user = models.ForeignKey(User, on_delete=models.CASCADE)
permission = models.SmallIntegerField()
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多对多关系的创建:
user --> account[permission]
u1 --> a1[1], a2[2]
u2 --> a1[2], a3[2]
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| import os
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'manytomany.settings')
import django
django.setup()
from a1.models import Account, User, PermissionSharing
a1 = Account.objects.create(name='a1')
a2 = Account.objects.create(name='a2')
a3 = Account.objects.create(name='a3')
u1 = User.objects.create(name='u1')
u2 = User.objects.create(name='u2')
PermissionSharing.objects.create(user=u1, account=a1, permission=1)
PermissionSharing.objects.create(user=u1, account=a2, permission=2)
PermissionSharing.objects.create(user=u2, account=a1, permission=2)
PermissionSharing.objects.create(user=u2, account=a3, permission=2)
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相互获取对方set的方法和filter方法:
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print(u1.accounts.all())
print(a1.user_set.all())
print(User.objects.filter(accounts__name='a1', permissionsharing__permission=1))
print(Account.objects.filter(user=u1, permissionsharing__permission=1))
ps = PermissionSharing.objects.get(user=u1, account=a1)
print(ps.permission)
ps = a1.permissionsharing_set.get(user=u1)
ps = u1.permissionsharing_set.get(account=a1)
print(ps.permission)
u1.accounts.clear()
Account.objects.all().delete()
User.objects.all().delete()
PermissionSharing.objects.all().delete()
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