class Image < ActiveRecord::Base belongs_to :auction_item belongs_to :item acts_as_list :scope => :auction_item_id acts_as_list :scope => :item_id has_attachment :content_type => :image, :storage => :file_system, :max_size => 500.kilobytes, :resize_to => '320x200>', :thumbnails => { :thumb => '100x100>' } validates_as_attachment end