How to implement “multiple database(db) connection” in rails3
- 1. How to implement “Multiple Database(DB) Connection” in Rails3?
In 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
- 2. 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])