class Category < ActiveRecord::Base has_and_belongs_to_many :posts has_and_belongs_to_many :special_posts, :class_name => "Post" has_and_belongs_to_many :hello_posts, :class_name => "Post", :conditions => "\#{aliased_table_name}.body = 'hello'" has_and_belongs_to_many :nonexistent_posts, :class_name => "Post", :conditions=>"\#{aliased_table_name}.body = 'nonexistent'" def self.what_are_you 'a category...' end has_many :categorizations has_many :authors, :through => :categorizations, :select => 'authors.*, categorizations.post_id' end class SpecialCategory < Category def self.what_are_you 'a special category...' end end