Ruby on rails 3.1 当注释可以属于另一个注释时，如何查询多态注释？

所以我尝试对多态模型进行一个相对高级的查询。我有以下型号：

class Project < ActiveRecord::Base
  has_many :project_stakeholders, :dependent => :destroy
  has_many :features, :dependent => :destroy
  has_many :iterations, :dependent => :destroy
  has_many :comments, :as => :commentable, :dependent => :destroy
end

class ProjectStakeholder < ActiveRecord::Base
  belongs_to :project
  has_many :comments, :as => :commentable, :dependent => :destroy
end

class Feature < ActiveRecord::Base
  belongs_to :project
  has_many :comments, :as => :commentable, :dependent => :destroy
end

class Iteration < ActiveRecord::Base
  belongs_to :project
  has_many :comments, :as => :commentable, :dependent => :destroy
end

class User < ActiveRecord::Base
  has_many :comments, :dependent => :destroy
end

class Comment < ActiveRecord::Base
  belongs_to :commentable, :polymorphic => true
  belongs_to :created_by, :class_name => 'User'
end

class项目:destroy
有很多：功能，：依赖=>：销毁
有多个：迭代，：依赖=>：销毁
有很多：注释，：as=>:commentable，：dependent=>:destroy
结束
类project涉众:commentable，：dependent=>:destroy
结束
类功能:commentable，：dependent=>:destroy
结束
类迭代:commentable，：dependent=>:destroy
结束
类用户：销毁
结束
类注释true
属于：创建人：class\u name=>'User'
结束

我正在尝试查找当前用户对特定项目的注释（project.comments、project.features.comments、project.iterations.comments、project.project\u涉众.comments），并将它们按降序排列在created\u中

我想到的最好的办法是：

Class Project < ActiveRecord::Base
  def all_comments_for_user(user)
    Comment.where(:created_by_id => user.id).select { |c| c.commentable.attributes.has_key?('project_id') }.select { |c| c.commentable.project == self } | comments.where(:created_by_id => user)
  end
end

Class项目user.id）。选择{c | c.commentable.attributes.has_key？（'project_id'））}。选择{c | c.commentable.project==self}注释。其中（：created_by_id=>user）
结束
结束

但这并没有解决递减的create_at序列。

类项目Class Project < ActiveRecord::Base
  def all_comments_for_user(user)
    Comment.where(:created_by_id => user.id).order('created_at DESC').select { |c| c.commentable.attributes.has_key?('project_id') }.select { |c| c.commentable.project == self } | comments.where(:created_by_id => user)
  end
end

为用户（用户）定义所有注释 Comment.where（：created_by_id=>user.id）。order（'created_at DESC'）。选择{c | c.commentable.attributes.has_key？（'project_id'））}。选择{c | c.commentable.project==self}注释。其中（：created_by_by_id=>user） 结束 结束

---

这行吗？我刚刚添加了订单（'created_at DESC'）

Boo。。。它没有对“管道”到第一个数组的project.comments进行排序。我无法理解。你能解释一下发生了什么事吗？此外，您还可以解释您试图对| comments.where（：created_by_id=>user）做什么。注释也可以属于项目。这就是把它们收集起来，并将它们添加到属于相关项目的注释的数组中。