find_values.rb

# Tag.find_values(:select => :user_id, :limit => 30) --> ["1", "3", "6"]
# Tag.find_values(:select => 'user_id, foobar', :limit => 30, :all=>true) --> [["1","A"], ["3","B"], ["6","C"]]
class ActiveRecord::Base
  def self.find_values(options)
    sql = self.send(:construct_finder_sql, options.except(:all))
    result = connection.select_rows(sql, name)
    if options[:all]
      result
    else
      result.map{|v| v[0] }
    end
  end
end