[ruby-on-rails] 협회를 통한 belongs_to

다음과 같은 연관성을 고려할 때 Questiona Choice가 Choice모델 에서 연결되어 있음 을 참조해야합니다 . belongs_to :question, through: :answer이 작업을 수행하는 데 사용하려고했습니다 .

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

나는 얻고있다

NameError 초기화되지 않은 상수 User::Choice

내가 할 때 current_user.choices

내가 포함하지 않으면 잘 작동합니다.

belongs_to :question, :through => :answer

그러나 나는 그것을 할 수 있기를 원하기 때문에 그것을 사용하고 싶습니다. validates_uniqueness_of

아마도 간단한 것을 간과하고있을 것입니다. 도움을 주시면 감사하겠습니다.

답변

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

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

class Choice
  belongs_to :user
  belongs_to :answer

  # ------- Helpers -------
  def question
    answer.question
  end

  # extra sugar
  def question_id
    answer.question_id
  end
end

class User
  has_many :questions
end

class Question
  belongs_to :user
  has_many   :answers
  has_one    :choice, :class_name => "Answer"

  validates_inclusion_of :choice, :in => lambda { answers }
end

class Answer
  belongs_to :question
end

class Choice
  belongs_to :user
  belongs_to :answer
  validates_uniqueness_of :answer_id, :scope => [ :question_id, :user_id ]
  ...
  def question
    answer.question
  end
end