touch_record

# File activerecord/lib/active_record/associations/builder/belongs_to.rb, line 43
    def self.touch_record(o, changes, foreign_key, name, touch) # :nodoc:
      old_foreign_id = changes[foreign_key] && changes[foreign_key].first

      if old_foreign_id
        association = o.association(name)
        reflection = association.reflection
        if reflection.polymorphic?
          foreign_type = reflection.foreign_type
          klass = changes[foreign_type] && changes[foreign_type].first || o.public_send(foreign_type)
          klass = o.class.polymorphic_class_for(klass)
        else
          klass = association.klass
        end
        primary_key = reflection.association_primary_key(klass)
        old_record = klass.find_by(primary_key => old_foreign_id)

        if old_record
          if touch != true
            old_record.touch_later(touch)
          else
            old_record.touch_later
          end
        end
      end

      record = o.public_send name
      if record && record.persisted?
        if touch != true
          record.touch_later(touch)
        else
          record.touch_later
        end
      end
    end