Error creating a new survey as the associated model(s) are invalid (questions)

Question

Hi,

I have a survey as part of an application I'm building. The user can create a survey and specify questions dynamically (can have as many as they want), so I've used an associated model with:

  #survey.rb
  has_many :survey_questions, :dependent => :destroy
  has_many :survey_answers, :dependent => :destroy

  after_update :save_survey_questions
  validates_associated :survey_questions

  def save_survey_questions
    survey_questions.each do |t|
      if t.should_destroy?
        t.destroy
      else
        t.save(false)
      end
    end
  end  

  def survey_question_attributes=(survey_question_attributes)
    survey_question_attributes.each do |attributes|
      if attributes[:id].blank?
        survey_questions.build(attributes)
      else
        survey_question = survey_questions.detect { |e| e.id == attributes[:id].to_i }
        survey_question.attributes = attributes
      end
    end
  end

  #surveys_controller.rb

  def new
    @survey = Survey.new
    if(@survey.survey_questions.empty?)
      @survey.survey_questions.build
    end
    respond_to do |format|
      format.html # new.html.erb
    end
  end

  def create
    @survey = Survey.new(params[:survey])
    respond_to do |format|
      if @survey.save
        format.html { redirect_to(survey_path(:id => @survey)) }
      else
        format.html { render :action => "new" }
      end
    end
  end

#survey_question.rb
class SurveyQuestion < ActiveRecord::Base
  belongs_to :survey
  attr_accessor :should_destroy

  def should_destroy?
    should_destroy.to_i == 1
  end

  validates_presence_of :question, :survey_id

end

The problem is when I submit I get an error on the questions:

@errors={"survey_questions"=>["is invalid", "is invalid", "is invalid"]}

I believe it is because the survey_id I have linking surveys to survey_questions is not being filled in.

Any ideas how I can overcome this?

If I create the survey with no questions, then add them afterwards via edit, then it works perfectly.

Answer 1

Hi, I'm pretty sure that accepts_nested_attributes can help you a lot, there you'll find some examples building the associated objects wich seems to be your problem (since the survey_id in survey_questions is not being filled in), basically you should define in your models something like:

class Survey < ActiveRecord::Base

  has_many :survey_questions
  accepts_nested_attributes_for :survey_questions, :allow_destroy => true

...
end

It will handle all the SurveyQuestions validations through Survey.

Answer 2

Your code looks close to the standard --> http://railscasts.com/episodes/75-complex-forms-part-3

Are you sure you are getting the question parameter back correctly? I only ask because that is the other thing you are validating against and you don't have the form code in there so I can't see what's coming back to the controller.

Answer 3

OK,

I've managed to fix it and it was a really silly mistake on my part.

In survey_question.rb I had the line :

validates_presence_of :question, :survey_id

However, rails automatically deals with survey_id because of the has_many belongs_to relationship!

So this should be validates_presence_of :question

I also in the process of finding this out upgraded rails to 2.3.4 and started using:

accepts_nested_attributes_for :survey_questions, :allow_destroy => true

which dealt with all the attributes etc.