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在Rails中找不到关联问题

models associations activerecord ruby-on-rails

Ash · 技术社区 · 15 年前

我是RubyonRails的新手,显然我有一个活动记录关联问题,但我无法独自解决它。

给定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

但当我执行控制器向申请表中添加问题时,我得到了错误:

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

有人能指出我做错了什么吗?

2 回复 | 直到 15 年前

Jim 15 年前

在ApplicationForm类中,您需要指定ApplicationForms与“form_questions”的关系。它还不知道。无论你在哪里使用 :through ,您需要先告诉它在哪里找到该记录。其他课程也有同样的问题。

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

bensie 15 年前

你需要包括一个

has_many :form_question_answers

在你的问题模型中。:through需要一个已经在模型中声明的表。

你的其他型号也一样——你不能提供 has_many :through 在您首次声明 has_many

# 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