active_hash_has_many.rb

module ActiveHash
  class Base
    
    def self.has_many(association_id, options = {})
      
      define_method(association_id) do       
        options = {
          :class_name => association_id.to_s.classify,
          :foreign_key => self.class.to_s.foreign_key
        }.merge(options)
        
        options[:class_name].constantize.send("find_all_by_#{options[:foreign_key]}", id)
      end
      
    end
    
  end 
end