class AddRoleIdIndexToRole sUsers ActiveRecord Migration def self up r

class AddRoleIdIndexToRolesUsers < ActiveRecord::Migration
  def self.up
    [:role_id, :user_id, [:role_id, :user_id]].each do |idx|
      add_index :roles_users, idx
    end
  end

  def self.down
    [:role_id, :user_id, [:role_id, :user_id]].each do |idx|
      remove_index :roles_users, idx
    end
  end
end

$ rake db:migrate 
(in /home/kron/DEV/pyramid2)
==  AddRoleIdIndexToRolesUsers: migrating =====================================
-- add_index(:roles_users, :role_id)
   -> 0.1420s
-- add_index(:roles_users, :user_id)
   -> 0.2503s
rake aborted!
An error has occurred, all later migrations canceled:

wrong number of arguments (1 for 0)

(See full trace by running task with --trace)