跨数据库外键错误 [英] Cross Database foreign key error

问题描述

这是我第一个数据库DB1的模型:

This my model of first Database DB1:

     from django.db import models 

     class Company(models.Model): 

          name = models.CharField(max_length=100, null=True)
          address = models.TextField(max_length=200, null=True)
          website = models.CharField(max_length=200, null=True)
          conatct_no = models.CharField(max_length=20, null=True)
          email = models.EmailField(max_length=20, null=True)
          logo = models.FileField(upload_to='logo/', blank=True, null=True)
          created = models.DateTimeField('company created', auto_now_add=True)
          updated = models.DateTimeField('company updated', auto_now=True, null=True)
          def __unicode__(self):  # Python 3: def __str__(self):
                return self.name

第二个数据库Db2的模型:

Model of 2nd Database Db2:

    from django.db import models

    from leavebuddymaster.models import Company

    class Department(models.Model): 
       company = models.ForeignKey(Company)
       department_name = models.CharField(max_length=50, null=True)
       created = models.DateTimeField('department created', auto_now_add=True)
       updated = models.DateTimeField('department updated', auto_now=True, null=True)
       def __unicode__(self):  # Python 3: def __str__(self):
            return self.department_name

现在，当我打开部门"表时，出现以下错误:

Now when i open the Department table it gives me a error as:

      ProgrammingError at /admin/leavebuddyapp/department/
      (1146, "Table 'leavebuddy_master.leavebuddyapp_department' doesn't exist")

我已经正确地为两个数据库完成了settings.py中的所有设置.你能指导我正确的方向吗?提前感谢.

I have done all the settings in settings.py correctly for the two databases. Can you please guide me in the right direction. Thanx in advance.

推荐答案

您是正确的，Django当前不支持跨多个数据库的外键关系. 来自跨数据库关系 [Edit 2020:Django version凹凸] :

You're correct, Django does not currently support foreign key relationships spanning multiple databases. From Cross-database relations :

如果您已使用路由器将模型分区到不同的数据库，则这些模型定义的任何外键和多对多关系必须在单个数据库内部.

这是因为参照完整性.为了维持两个对象之间的关系，Django需要知道相关对象的主键有效.如果主键存储在单独的数据库中，则无法轻松评估主键的有效性.

This is because of referential integrity. In order to maintain a relationship between two objects, Django needs to know that the primary key of the related object is valid. If the primary key is stored on a separate database, it’s not possible to easily evaluate the validity of a primary key.

我认为您可以尝试使用的解决方案(尽管它可能会出现其他问题):

A solution I thought up that you could try (though it may present other problems):

from leavebuddymaster.models import Company

class Department(models.Model): 
    company_id = models.IntegerField()
    
    @property
    def company(self):
        return Company.objects.get(pk=self.company_id)

这使您可以像在示例中通常一样引用Department.company.设置它只是Department.company_id = Company.pk的问题.希望它会有所帮助，或者至少会激发出更好的解决方案！

This allows you to refer to Department.company like you normally would in your example. Setting it would just be a matter of Department.company_id = Company.pk. Hope it helps, or at least inspires a better solution!

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