如何为cancan指定条件

Question

我正在使用带有cancan 1.1的Rails 2.3.11 我想添加一个新角色，允许用户在属于一个特定组织的那些“出版物”中创建/编辑“出版物”并创建/编辑“文章”。正如我所提到的，由于我正在运行较旧的cancan 1.1，我无法在doc中尝试所有新示例。这是我在Ability.rb中尝试过的一个例子：

class Ability
  include CanCan::Ability

  #additional roles require changes be made to config/environment.rb ROLES constant 
  def initialize(user)
    user ||= User.new # Guest user

    # Multirole environment

    if user.role? :admin
      can :manage, :all
      can :archive, Article
      can :review, Article
    end
   #several other roles ...

   #This is not working...I'm specify the organization that I want the super_user to be able to create and edit for

   if user.role? :super_user
     can [:create, :edit], Publication, :organization_id => 21
     can [:create, :edit], Article, :organization_id => 21  
   end

我有以下三种模式：

class Organization < ActiveRecord::Base
  #validations here

  has_many :publications, :dependent => :destroy
  has_many :articles, :through => :publications
end

class Publication < ActiveRecord::Base
  #validations here  
  has_many :articles, :dependent => :destroy

end

class Article < ActiveRecord::Base
  #validations here ...

  belongs_to :publication
  validates_associated :publication
  #...

end

感谢您提出任何建议。