Puts Chronic in front of date, time, and datetime attributes to allow for flexile input (anything supported by Chronic)

chronic_attribute.rb

module ChronicAttribute
  extend ActiveSupport::Concern

  module ClassMethods
    def chronic(*attrs)
      attrs.each do |attr|
        define_method "#{attr}=" do |value|
          if value.is_a? String
            with_utc do
              self[attr] = Chronic.parse(value)
            end
          else
            super(value)
          end
        end
      end
    end
  end

  private

  def with_utc
    old_class = Chronic.time_class

    Time.use_zone("UTC") do
      Chronic.time_class = Time.zone
      yield
    end
  ensure
    Chronic.time_class = old_class
  end
end

example.rb

class Task < ActiveRecord::Base
  include ChronicAttribute
  chronic :due_date
end