application_helper.rb

module ActionView
  module Helpers
    class DateTimeSelector
      # Override
      # クレジットカード用に年を２桁で表示する "use_short_year" オプションを追加した
      def select_year
        if !@datetime || @datetime == 0
          val = '1'
          middle_year = Date.today.year
        else
          val = middle_year = year
        end

        if @options[:use_hidden] || @options[:discard_year]
          build_hidden(:year, val)
        else
          options                     = {}
          options[:start]             = @options[:start_year] || middle_year - 5
          options[:end]               = @options[:end_year] || middle_year + 5
          options[:step]              = options[:start] < options[:end] ? 1 : -1
          options[:leading_zeros]     = false
          options[:max_years_allowed] = @options[:max_years_allowed] || 1000
          if @options[:use_short_year]
            options[:start] = options[:start].to_s.gsub(/^\d{2}(\d{2})$/, '\1').to_i
            options[:end] = options[:end].to_s.gsub(/^\d{2}(\d{2})$/, '\1').to_i
          end

          if (options[:end] - options[:start]).abs > options[:max_years_allowed]
            raise ArgumentError,  "There're too many years options to be built. Are you sure you haven't mistyped something? You can provide the :max_years_allowed parameter"
          end

          build_options_and_select(:year, val, options)
        end
      end
    end
  end
end