ruby-on-rails - CanCan之间的区别:read and [:index, :show]?

Question

根据所有文档，:read操作被别名为:index和:show:

alias_action :index, show, :to => :read

但是，请考虑以下带有嵌套资源的情况:

resources :posts
  resources :comments
end

如果我这样定义能力:

# ability.rb
can :read, Post
can :show, Comment

# comments_controller.rb
load_and_authorize_resource :organization, :find_by => :permalink
load_and_authorize_resource :membership, :through => :organization

事情按预期进行。但是，如果我将 :read操作更改为[:index，:show]:

# ability.rb
can [:index, :show], Post
can :show, Comment

# comments_controller.rb
load_and_authorize_resource :organization, :find_by => :permalink
load_and_authorize_resource :membership, :through => :organization

我无权访问 /posts/:post_id/comments， /posts/:post_id/comments/:id等。但是，我仍然可以访问 :index的 :show和 posts_controller。

如果它们的行为不同，怎么可能“混淆”这些行为？

在摆弄我的同时，我还遇到了以下问题。将 load_and_authorize_resource更改为以下允许的访问:

# ability.rb
can [:index, :show], Post
can :show, Comment

# comments_controller.rb
load__resource :organization, :find_by => :permalink
load_and_authorize_resource :membership, :through => :organization

有人可以解释这是怎么回事吗？

Answer 1

我将此作为问题发布在GitHub上。瑞安回应如下:

Both the :index and :show actions point to the :read action. But when CanCan authorizes a parent resource it uses the :read action directly which is why you're seeing this behavior.

I think this has caused confusion before, so I will change the internal behavior to never use the :read action directly. Instead of a :parent resource I'll change it to use :show and for the accessible_by default I will use :index instead of :read. Thanks for bringing this to my attention.

https://github.com/ryanb/cancan/issues/302#comment_863142