How to use DB router in Django 1.4

Question

I\'ve been trying to setup Django 1.4.3 to use multiple DBs, but for the life of me I can\'t make it to work. I read the documentation and posts on SO, and did the following

Answer 1

I found out that the statement in step 3 "from django.db import connections " was preventing the DB router to be registered. When I removed this statement, the router was registered and stuff started to work as expected.

Answer 2

I think the problem is probably arising because your routers.py only returns a reference to 'db1' but as you say you're only being routed to 'default' I'm unsure (I would expect it to be the only routed to 'db1'.

In routers.py create a master router class, and then subclass for each DB - and initialise with an app_label string so you can set them apart.

class MasterRouter(object):
    def __init__(self, app_label):
        super(MasterRouter, self).__init__()
        self.app_label = app_label

    def db_for_read(self, model, **hints):
        if model._meta.app_label == self.app_label:
            return self.app_label
        return None

    def db_for_write(self, model, **hints):
        if model._meta.app_label == self.app_label:
            return self.app_label
        return None

    def allow_relation(self, obj1, obj2, **hints):
        if obj1._meta.app_label == self.app_label or obj2._meta.app_label == self.app_label:
            return True
        return None

    def allow_syncdb(self, db, model):
        if db == 'default':
            return model._meta.app_label == self.app_label
        elif model._meta.app_label == self.app_label:
            return False
        return None

class DefaultRouter(MasterRouter):
    def __init__(self):
        super(DefaultRouter, self).__init__('default')

class DB1Router(MasterRouter):
    def __init__(self):
        super(DB1Router, self).__init__('db1')

and then in your settings.py declare the routers

DATABASE_ROUTERS = [ 'routers.DefaultRouter', 'routers.DB1Router' ]

ofcourse, you'll probably want to set up your MasterRouter class overrides differently.