[Django]-Django multi-database routing

OK, so I just solved my own problem. The router class goes into a separate file called routers.py under /myapp2. No meta.app_label is required as I guess it is automatically assigned. Hope this helps someone. I have also documented the process here.

Did not help me, so I did some debugging. Maybe the results can save someone some pain. 🙂
The problem in django 1.4 is a circular reference that occurs when django tries to import the custom router class.
This happens in django.db.utils.ConnectionRouter. In my case the app’s __init__.py imported a module (tastypie.api to be precise) that in turn (and through a long chain) imported django.db.models. That is not bad in itself, but models tries to import connection from django.db and that happens to have a dependency on ConnectionRouter. Which is exactly where our journey started. Hence the error.

This is described as a bug in django < 1.6 here: https://code.djangoproject.com/ticket/20704 and there is a nice small changeset thats supposed to fixed it in django 1.6:https://github.com/django/django/commit/6a6bb168be90594a18ab6d62c994889b7e745055

My solution however was to simply move routers.py from the app directory to the project directory. No nasty dependencies there.

One more mistake to ommit, is to import the models in the router, this will lead to the same error, even if the router is defined in a different file.

If you have one app that uses multiple databases you can route on a per application and per table basis. For example if your app is “console” and you only want the “PoolServers” model to come from a different back end you would put this in your routers.py

class PoolServerRouter(object): 
def db_for_read(self, model, **hints):
    "Point only reads to poolserver  model to 'hamburger'"
    if model._meta.app_label == 'console' and model._meta.db_table == 'PoolServers':
        return 'hamburger'
    return 'default'