ruby-on-rails - before_filter :require_owner

Question

我有许多资源(行程、时间表等)，其操作应该仅限于资源的所有者。

您如何使用 ApplicationController 中定义的 #require_owner 方法实现代码以实现此目的？理想情况下，代码将查找所有者的继承链，因此 before_filter 将处理一个 :comment thatbelongs_to :trip thatbelongs_to :user。

class TripsController < ApplicationController
  belongs_to :member
  before_filter :require_owner

  ...

end

Answer 1

我没有完全遵循描述(评论真的属于旅行所有者吗？)，但稍微扩展了 jonnii 的答案，这是一个限制旅行 Controller 的示例:

class ApplicationController < ActionController::Base
  ...
protected
  # relies on the presence of an instance variable named after the controller
  def require_owner
    object = instance_variable_get("@#{self.controller_name.singularize}")
    unless current_user && object.is_owned_by?(current_user)
      resond_to do |format|
        format.html { render :text => "Not Allowed", :status => :forbidden }
      end
    end
  end
end

class TripsController < ApplicationController
  before_filter :login_required # using restful_authentication, for example
  # only require these filters for actions that act on single resources
  before_filter :get_trip, :only => [:show, :edit, :update, :destroy]
  before_filter :require_owner, :only => [:show, :edit, :update, :destroy]
  ...
protected
  def get_trip
    @trip = Trip.find(params[:id])
  end
end

假设模型如下所示:

class Trip < ActiveRecord::Base
    belongs_to :owner, :class_name => 'User'
    ...
    def is_owned_by?(agent)
      self.owner == agent
      # or, if you can safely assume the agent is always a User, you can 
      # avoid the additional user query:
      # self.owner_id == agent.id
    end
end

login_required方法(由restful_authentication 或authlogic 等身份验证插件提供或依赖)确保用户已登录并为用户提供 current_user方法， get_trip设置行程实例变量，然后在 require_owner 中检查该变量.

如果模型已经实现了 is_owned_by?，这个相同的模式几乎可以适用于任何其他资源。方法。如果您在资源是评论时尝试检查它，那么您会在 CommentsController 中。 :

class CommentsController < ApplicationController
  before_filter :login_required # using restful_authentication, for example
  before_filter :get_comment, :only => [:show, :edit, :update, :destroy]
  before_filter :require_owner, :only => [:show, :edit, :update, :destroy]

  ...
protected
  def get_comment
    @comment = Comment.find(params[:id])
  end
end

与 Comment看起来像的模型:

class Comment < ActiveRecord::Base
  belongs_to :trip

  # either 
  #  delegate :is_owned_by?, :to => :trip
  # or the long way:
  def is_owned_by?(agent)
    self.trip.is_owned_by?(agent)
  end
end

确保在执行此操作时检查日志，因为如果您不小心，依赖于关联的检查可能会膨胀成大量查询。