ruby-on-rails – 使用Rails的CanCan gem来处理has_and_belongs_

> has_and_belongs_to_many餐厅的用户模型,反之亦然.
>餐馆模型has_and_belongs_to_many用餐,反之亦然.

在我的ability.rb文件中,我想指定用户只能管理他“has_and_belongs_to”(即用户餐馆中的餐馆)的餐馆的饭菜.

我现在有这个：

class Ability
  include CanCan::Ability
  def initialize(user)
    # a user can only manage meals of restaurants he has access to
    can :manage,Meal do |meal| 
      meal.restaurant_ids & user.restaurant_ids #...this doesn't work...
    end
  end
end

最好的方法是什么？

我咨询了https://github.com/ryanb/cancan/wiki/Defining-Abilities-with-Blocks,但我还是不知道.