monkey patch to add random_order to ActiveRecord with multi DB driver

random_order.rb

# for rails 3 or higher

module ActiveRecord
  module Querying
    delegate :random_order, :to => :scoped
  end

  module QueryMethods
    def random_order
      relation = clone
      name = connection.adapter_name
      case name
      when 'SQLite', 'PostgreSQL'
        relation.order_values += ['random()']
      when /Mysql/
        relation.order_values += ['rand()']
      else
        raise "random_order doesn't support this adapter"
      end
      relation
    end
  end
end