update_attributes fix for counter_cache

associations.rb

   def belongs_to(association_id, options = {})
     association_column = options[:foreign_key] ||= association_id.to_s + "_id" #
     reflection = create_belongs_to_reflection(association_id, options)

     if reflection.options[:polymorphic]
       association_accessor_methods(reflection, BelongsToPolymorphicAssociation)
     else
       association_accessor_methods(reflection, BelongsToAssociation)
       association_constructor_method(:build,  reflection, BelongsToAssociation)
       association_constructor_method(:create, reflection, BelongsToAssociation)
     end

     # This is the part i added
     if options[:counter_cache]
       define_method("#{association_column}=") do |*params|
         new_associated_id = params.first unless params.empty?
         current_associated_id = self.send("#{association_column}")
         reflection.class_name.constantize.update_counters current_associated_id, reflection.counter_cache_column.to_sym => -1
         reflection.class_name.constantize.update_counters new_associated_id, reflection.counter_cache_column.to_sym => +1
         self.attributes[association_column.to_sym] = new_associated_id
       end
       add_counter_cache_callbacks(reflection)          
     end
     add_touch_callbacks(reflection, options[:touch]) if options[:touch]

     configure_dependency_for_belongs_to(reflection)
   end