Cross Database foreign key error - django

Question

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
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
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")
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.

Answer 1

You're correct, Django does not currently support foreign key relationships spanning multiple databases.
From Cross-database relations [Edit 2020: Django version bump]:
If you have used a router to partition models to different databases, any foreign key and many-to-many relationships defined by those models must be internal to a single database.
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.
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)
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!