Load Rails submodule models with different database.

load_submodule_models.rb

# rails_root/config/initializers/load_submodule_models.rb

RAILS_MODEL_LIST = %w(
Account
Plan
User
UserPreference
)

def apply_db_change(class_name)
    eval(<<EOT)
class #{class_name} < ActiveRecord::Base
  establish_connection(
    :adapter  => "mysql2",
    :host     => "localhost",
    :database => "another_db_name",
    :username => "root",
    :password => nil
  )
end
EOT
end

RAILS_MODEL_LIST.each do |class_name|
  apply_db_change(class_name)
  require class_name.underscore # load model forcibly
end