Sometimes when using Active Record you may want to create a database connection to a database other than the default database specified in your database.yml file.

When this happens, the easiest way to do it is to use the Class-level convenience method on ActiveRecord::Base. Like this:

Imagine your database.yml entry looks like this:

development_foo:
  adapter: mysql
  encoding: utf8
  database: foo
  pool: 5
  username: my_user
  password: my_pass
  socket: /tmp/mysql.sock

Now you want to create active record models that use that database connection. Here’s how:

# 'Bar' model points to the table 'bars' in the database 'foo'

class Bar < ActiveRecord::Base

  # specify the database.yml entry
  $db_config = 'development_foo'

  # Fetch the database.yml configuration
  $config = ActiveRecord::Base.configurations[$db_config]

 # Now we can establish a connection to that database and
 # this ActiveRecord model class will point to that database.
  establish_connection $config

end

It’s simple!

Copyright Kevin Bedell, 2009
All this code can be freely used under the terms of the MIT License.