Question

我是Ruby on Rails的新手，我显然有一个活跃的记录关联问题，但我无法自己解决。

鉴于三个模型类及其关联：

# application_form.rb
class ApplicationForm < ActiveRecord::Base
  has_many :questions, :through => :form_questions
end

# question.rb
class Question < ActiveRecord::Base
  belongs_to :section
  has_many :application_forms, :through => :form_questions
end

# form_question.rb
class FormQuestion < ActiveRecord::Base
  belongs_to :question
  belongs_to :application_form
  belongs_to :question_type
  has_many :answers, :through => :form_question_answers
end

但是当我执行控制器向应用程序表单添加问题时，我收到错误：

ActiveRecord::HasManyThroughAssociationNotFoundError in Application_forms#show

Showing app/views/application_forms/show.html.erb where line #9 raised:

Could not find the association :form_questions in model ApplicationForm

有谁可以指出我做错了什么？

Answer 1

在ApplicationForm类中，您需要指定ApplicationForms与'form_questions'的关系。它还不知道。在您使用:through的任何地方，您需要先告诉它在哪里找到该记录。与其他课程相同的问题。

所以

# application_form.rb
class ApplicationForm < ActiveRecord::Base
  has_many :form_questions
  has_many :questions, :through => :form_questions
end

# question.rb
class Question < ActiveRecord::Base
  belongs_to :section
  has_many :form_questions
  has_many :application_forms, :through => :form_questions
end

# form_question.rb
class FormQuestion < ActiveRecord::Base
  belongs_to :question
  belongs_to :application_form
  belongs_to :question_type
  has_many :form_questions_answers
  has_many :answers, :through => :form_question_answers
end

这就是假设你设置它的方式。

Answer 2

您需要添加

has_many :form_question_answers

在FormQuestion模型中。：through期望一个已经在模型中声明的表。

您的其他型号也是如此 - 在您首次声明has_many :through

之前，您无法提供has_many关联

# application_form.rb
class ApplicationForm < ActiveRecord::Base
  has_many :form_questions
  has_many :questions, :through => :form_questions
end

# question.rb
class Question < ActiveRecord::Base
  belongs_to :section
  has_many :form_questions
  has_many :application_forms, :through => :form_questions
end

# form_question.rb
class FormQuestion < ActiveRecord::Base
  belongs_to :question
  belongs_to :application_form
  belongs_to :question_type
  has_many :form_question_answers
  has_many :answers, :through => :form_question_answers
end

看起来您的架构可能有点不稳定，但重点是您始终需要首先为连接表添加has_many，然后添加直通。

无法在Rails中找到关联问题

2 个答案: