How to implement “Multiple Database(DB) Connection” in Rails3 by Jay December 3, 2012 2 Minutes ReadIn some scenarios we need data from a external database to execute in different application. Here, we need a bridge which will connect these two different databases. In Ruby on Rails this can be achieved through ActiveRecord’s establish_connection(). Following are the steps to create a rails application which uses multiple database, where the existing database and the external database will work simultaneously. Let’s say there are two different rails application say “myapp” and “remoteapp” where “myapp” depends upon “remoteapp” user table. Step#1 Edit the ‘database.yml‘ file for the ‘myapp‘ project Add a new connection for ‘remoteapp‘ as below: # Connection name, it will be used to connect from myapp connect_remote: adapter: mysql2 username: user_name # username of the remoteapp database password: password # password of the remoteapp database pool: 5 database: remoteapp_db_name # database name of the remoteapp host: www.remoteapphost.com # host name of the db Step#2 In models folder create a new file called user.rb if it is not already there. Write below code to establish connection with remote app’s database. class User < ActiveRecord::Base establish_connection("connect_remote") end Here use the connection name defined in the database.yml file in the establish_connection() method. Like this you can create models to connect with remote databases. Step#3 It will give you the flexibility for managing users data of remote app’s database like it is present in the myapp database. Use the normal way to get data from the users table like User.all #To get all the records User.find(id) #To get required record Here you can also insert or update data in users table by normal way as it is present in myapp application #insert new record user = User.new params[:user] user.save #update existing record user = User.find params[:id] user.update_attributes(params[:user]) Related Posts: How to customize Devise authentication in Rails3? Steps to execute pagination using “Kaminari” gem in Rails3 How to Implement Event Calendar in Rails App Tags: Rails App Jayadev Das firstname.lastname@example.org Do what you do best in – that’s what I’ve always believed in and that’s what I preach. Over the past 25+ years (yup that’s my expertise ‘n’ experience in the Information Technology domain), I’ve been consulting to small, medium and large companies ‘bout Web Technologies, Mobile Future as well as on the good-and-bad of tech. Blogger, International Business Advisor, Web Technology Expert, Sales Guru, Startup Mentor, Insurance Sales Portal Expert & a Tennis Player. And top of all – a complete family man!