rails : How can I call methods in the nested model from parents? -

this model.

survey

class survey < activerecord::base   belongs_to :user   has_many :questions, :dependent => :destroy   accepts_nested_attributes_for :questions, :reject_if => lambda {|a| a[:content].blank?}, :allow_destroy => true 

question : there is_correct(boolean) column indicates whether students right answer or not.

class question < activerecord::base   belongs_to :survey   has_many :answers, :dependent => :destroy   accepts_nested_attributes_for :answers, :reject_if => lambda { |a| a[:content].blank? }, :allow_destroy => true 

answer : there correct(boolean) column teacher checks making survey(test), , there user_answer(boolean) column students mark taking test.

class answer < actviverecord::base   belongs_to :question 

i want compare correct , user_answer in answer model, , save answer is_correct in question model.

there not basic crud methods generating question , answer, 3 methods answering(get)/grading(post) examination, showing(get) results. can check there no problem in routes result of rake routes.

updated question : changed controller , question model.

here methods in survey controller.

def answering   @survey = survey.find(params[:id]) end  def grading   @survey = survey.find(params[:id])   @survey.user_id = current_user.id   @survey.questions.each |q|     q.auto_check    end    redirect_to results_survey_path(@survey) end  def results end 

here question controller.

def auto_check   answers.each |a|     is_correct = true if a.user_answer , a.correct      self.save!   end end 

the result of rake routes.

$ rake routes | grep survey (in /home/seriousin/classcasts)         answering_survey    /surveys/:id/answering(.:format)            surveys#answering           grading_survey post   /surveys/:id/grading(.:format)              surveys#grading           results_survey    /surveys/:id/results(.:format)              surveys#results                  surveys    /surveys(.:format)                          surveys#index                          post   /surveys(.:format)                          surveys#create               new_survey    /surveys/new(.:format)                      surveys#new              edit_survey    /surveys/:id/edit(.:format)                 surveys#edit                   survey    /surveys/:id(.:format)                      surveys#show                          put    /surveys/:id(.:format)                      surveys#update                          delete /surveys/:id(.:format)                      surveys#destroy 

*the problem can't call survey object saved user input. *

i let results method empty. using redirect_to, don't need generate survey object.

  def results       #@survey = survey.where(params[:survey_id])   end 

i think it's ok. because can pass survey object parameter grading method.

def grading   @survey = survey.find(params[:id])   @survey.user_id = current_user.id   @survey.questions.each |q|     q.auto_check    end    redirect_to results_survey_path(@survey) end 

but result 'undefined method `name' nil:nilclass'... how can use object contains user input?

thanks advanced.

your @survey.questions.each gives instance of question model , calling method defined in questionscontroller on it. had auto_check been member of question model wouldn't have received error.

if want keep auto_check method in questionscontroller think should pass in question instance parameter follows:

def auto_check(question)   question.answers.each |a|     is_correct = true if a.user_answer , a.correct      ...   end end 

and update call follows:

@survey.questions.each |q|   auto_check(q) end