Django - Multiple Databases

Question

So I'm somewhat new to the whole Django databases and maybe I just don't fully understand the Django routers talked about here: https://docs.djangoproject.com/en/dev/topics/db/multi-db/#database-routers but for the life of me I cant figure out how to link two databases together. Maybe it's because my set-up is different? The two databases are separate Django project folders and both have separate Postgre databases. I think that maybe the problem comes form them being in different folders and I'm not including the path names properly?

Here's what I have now:

settings.py:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2', 
        'NAME': 'ClothesWashers',
        'USER': '',
        'PASSWORD': '',
        'HOST': '',
        'PORT': '',
        },
    'RECS': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'RECS',
        'USER': '',
        'PASSWORD': '',
        'HOST': '',
        'PORT': '',
        }
}

and

INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django.contrib.admin',
    'django_extensions',
    'ClothesWasher_Purchaser',
    )

and

DATABASE_ROUTERS = ['ClothesWashers.db_routers.RECS_Router',]

db_routers.py:

class RECS_Router(object):
    def db_for_read(self, model, **hints):
        if model._meta.app_label == 'RECS_Data':
            return 'RECS'
        return 'default'

All I want to be able to do is call the RECS_Data app in the RECS database by doing something like this so that I can read from it:

import os
os.environ['DJANGO_SETTINGS_MODULE'] = 'ClothesWashers.settings'
from RECS_Data.models import RecsData
g = RecsData._meta.fields

Thank you anyone who would be willing to help me!

what do you mean by "The two databases are separate Django project folders and both have separate Postgre databases" — dm03514
– dm03514, Commented May 1, 2013 at 23:54
I have one Django project called RECS which has an associated postgres database (called RECS) with one app called RECS_Data. I am now trying to make a completely separate Django project called ClothesWashers which also has it's own postgres database. Basically all I want to be able to do is read from the the RECS database and put data into the ClothesWashers database. Both project folders are in a folder called "Django Projects". — Radical Edward
– Radical Edward, Commented May 2, 2013 at 0:11

Yuv · Accepted Answer · 2014-06-23 08:46:33Z

1

I guess you can read a secondary database with using.

Try like this.

i.e RecsData.using("RECS")._meta.fields

For more refer here https://docs.djangoproject.com/en/dev/topics/db/multi-db/#manually-selecting-a-database

answered Jun 23, 2014 at 8:46

Yuv

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2 Comments

IcarusNM Over a year ago

Kudos for this Q&A. The main Django documentation about using "Multiple Databases" is really about using "Multiple RDBMS Instances". In other words, having fail-over or redundant data sources to poll, in some order, for reliability or load balancing. What about a single Project that needs to literally query two DATABASES? The Django application model centers around One Project, One Database, with Many Apps, Many Tables. If you are starting a Django app from scratch, sure. But if you need a GUI to help join/integrate existing databases, this "using()" feature is very important. Thanks!

Gustavo Gonçalves Over a year ago

@IcarusNM you are right. The use case of two complete independent databases is not covered in Django multiple databases implementation. I'm still looking for a solution to that, and I'm thinking of spliting the project in two, or use SQLAlchemy for one of the databaes.

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