Classic behaviour of belongs_to :touch => true for Rails 3, using save! instead of update_all

nudgeable_association.rb

# This snippet will provide a :nudge option for belongs_to associations,
# which behaves like the belongs_to :touch => true did in Rails 2.x.
# It will use save! instead of a sneaky update_all call, so all of your
# callbacks and validations will be invoked.

module ActiveRecord::NudgeableAssociation
  
  def self.included(base)
    base.extend ClassMethods
    (class << base; self; end).instance_eval do
      alias_method_chain :belongs_to, :nudge
    end
  end
  
  module ClassMethods

    def belongs_to_with_nudge(name, options = {})
      if nudge_attribute = options.delete(:nudge)
        add_nudge_callbacks(name, nudge_attribute)
      end
      belongs_to_without_nudge(name, options)
    end
    
    private
    
    def add_nudge_callbacks(association_name, nudge_attribute)
      method_name = "belongs_to_nudge_after_save_or_destroy_for_#{association_name}".to_sym
      define_method(method_name) do
        association = send(association_name)
        return if association.nil?
        if nudge_attribute == true
          association.nudge
        else
          association.nudge(nudge_attribute)
        end
      end
      after_save(method_name)
      after_destroy(method_name)
    end

  end
  
  def nudge(attribute = nil)
    current_time = current_time_from_proper_timezone
    if attribute
      write_attribute(attribute, current_time)
    else
      write_attribute('updated_at', current_time) if respond_to?(:updated_at)
      write_attribute('updated_on', current_time) if respond_to?(:updated_on)
    end
    save!
  end
  
end

ActiveRecord::Base.instance_eval { include ActiveRecord::NudgeableAssociation }