通过关联属于_to

鉴于以下关联，我需要参考Question that a Choice是通过从Choice模型。我一直在尝试使用belongs_to :question, through: :answer来执行此操作。

class User
  has_many :questions
  has_many :choices
end

class Question
  belongs_to :user
  has_many :answers
  has_one :choice, :through => :answer
end

class Answer
  belongs_to :question
end

class Choice
  belongs_to :user
  belongs_to :answer
  belongs_to :question, :through => :answer

  validates_uniqueness_of :answer_id, :scope => [ :question_id, :user_id ]
end

我正进入（状态

NameError 未初始化常量User::Choice

当我尝试做的时候current_user.choices

如果我不包括的话，它工作得很好

belongs_to :question, :through => :answer

但我想用它，因为我希望能够做到validates_uniqueness_of

我可能忽略了一些简单的事情。任何帮助，将不胜感激。

您还可以委托：

class Company < ActiveRecord::Base
  has_many :employees
  has_many :dogs, :through => :employees
end

class Employee < ActiveRescord::Base
  belongs_to :company
  has_many :dogs
end

class Dog < ActiveRecord::Base
  belongs_to :employee

  delegate :company, :to => :employee, :allow_nil => true
end