modify Rails 3.0 LengthValidator to accept Proc objects as length-limit and message options

99_length_validator_patch.rb

#

# modify LengthValidator to accept Proc objects as length-limit and message options

module ActiveModel

  # == Active Model Length Validator
  module Validations
    class LengthValidator

      def initialize(options)
        if range = (options.delete(:in) || options.delete(:within))
          options[:within] = range
          raise ArgumentError, ":in and :within must be a Range or a Proc" unless range.is_a?(Range) || range.is_a?(Proc)
        end

        super(options.reverse_merge(:tokenizer => DEFAULT_TOKENIZER))
      end

      def gather_options
        tmp_options = Hash[options] # make a unfrozen copy of options
        range = tmp_options[:within]
        if range
          range = range.call if range.is_a?(Proc)
          raise ArgumentError, ":in and :within must be a Range or a Proc" unless range.is_a?(Range)
          tmp_options[:minimum], tmp_options[:maximum] = range.begin, range.end
          tmp_options[:maximum] -= 1 if range.exclude_end?
        end
        tmp_options[:minimum] = tmp_options[:minimum].call if tmp_options[:minimum].is_a?(Proc)
        tmp_options[:maximum] = tmp_options[:maximum].call if tmp_options[:maximum].is_a?(Proc)
        tmp_options
      end

      def check_validity!
        true # FIXME: no load-time sanity checks???
      end

      def validate_each(record, attribute, value)
        tmp_options = gather_options

        value = options[:tokenizer].call(value) if value.kind_of?(String)

        CHECKS.each do |key, validity_check|
          next unless check_value = tmp_options[key]

          value ||= [] if key == :maximum

          next if value && value.size.send(validity_check, check_value)

          errors_options = options.except(*RESERVED_OPTIONS)
          errors_options[:count] = check_value

          default_message = options[MESSAGES[key]]
          errors_options[:message] ||= default_message if default_message
          errors_options[:message] = errors_options[:message].call if errors_options[:message].is_a?(Proc)

          record.errors.add(attribute, MESSAGES[key], errors_options)
        end
      end
    end
  end
end