How to handle multiple models in one rails form?

Question

I have the following models

class Survey < ActiveRecord::Base
  has_many :survey_sections
  accepts_nested_attributes_for :survey_sections
end

class SurveySection < ActiveRecord::Base
  belongs_to :survey
  has_many :questions
  accepts_nested_attributes_for :questions
end

class Question < ActiveRecord::Base
  belongs_to :survey_section
  has_many :answers
  belongs_to :question_group
  accepts_nested_attributes_for :question_group
  accepts_nested_attributes_for :answers
end

class Answer < ActiveRecord::Base
  belongs_to :question
end

class QuestionGroup < ActiveRecord::Base
  has_many :questions
end

My Controller:

 def new
    @survey = Survey.new
    survey_section = @survey.survey_sections.build
    survey_section.questions.build
  end

 def create
    @survey = Survey.new(survey_params)
    if @survey.save
      redirect_to @survey, notice: 'Super'
    else
      render 'new'
    end
  end

 def survey_params
      params.require(:survey).permit(:title, :description, survey_sections_attributes:[:id, :title, questions_attributes:[:id, :text, answers_attributes:[:id, :text]]])
    end

How it is possible to save data in more then 3 models? At the moment i can save from my survey form data into the survey, survey section and question model. But i don't know what i have to in the controller that i can save data into the other models.

My suggestion is to avoid using nested_forms. It's so called rails way, but it increases complexity and coupling a lot. It's better to create form with a little bit more effort manually and use Form object to deal with it. You can google this approach. — vladra, Oct 01 '15 at 09:51

score 20 · Accepted Answer · edited May 23 '17 at 10:30

You can handle as many forms as you need, if you use the fields_for helper properly.

This is where you're falling short I think (your controller seems okay).

I also wrote an answer about this some time back.

#app/models/survey.rb
class Survey < ActiveRecord::Base
    has_many :sections
    accepts_nested_attributes_for :sections
end

#app/models/section.rb
class Section < ActiveRecord::Base
    belongs_to :survey
    has_many :questions
    accepts_nested_attributes_for :questions
end

#app/models/question.rb
class Question < ActiveRecord::Base
    belongs_to :section
    has_many :answers
end

Try and keep your model names as succinct as possible.

#app/controllers/surveys_controller.rb
class SurveysController < ApplicationController
   def new
      @survey = Survey.new
      @survey.sections.build.questions.build
   end

   def create
      @survey = Survey.new survey_params
      @survey.save
   end

   private 

   def survey_params
      params.require(:survey).permit(:title, sections_attributes: [:title, questions_attributes:[:title]])
   end
end

#app/views/surveys/new.html.erb
<%= form_for @survey do |f| %>
   <%= f.text_field :title %>
   <%= f.fields_for :sections do |section| %>
       <%= section.text_field :title %>
       <%= section.fields_for :questions do |question| %>
           <%= question.text_field :title %>
       <% end %>
   <% end %> 
   <%= f.submit %>
<% end %>

It took me half an hour and about 40 chrome tabs to finally find this answer, which fixed my problem in 2 minutes. Thank you! — stevec, Feb 06 '21 at 10:33

score 1 · Answer 2 · answered Oct 01 '15 at 10:47

You can get best explanation here with same type of model

http://railscasts.com/episodes/196-nested-model-form-part-1

#app/models/survey.rb
class Survey < ActiveRecord::Base
    has_many :sections, :dependent => :destroy
    accepts_nested_attributes_for :sections, :allow_destroy => true
end

#app/models/section.rb
class Section < ActiveRecord::Base
    belongs_to :survey
    has_many :questions, :dependent => :destroy
    accepts_nested_attributes_for :questions, :allow_destroy => true
end

#app/models/question.rb
class Question < ActiveRecord::Base
    belongs_to :section
    has_many :answers
end

now in controller

def new
  @survey = Survey.new
  section = @survey.sections.build
  section.questions.build 
  end
end

Now in views

<%= form_for @survey do |f| %>
  <%= f.error_messages %>
  <p>
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </p>
  <%= f.fields_for :sections do |builder| %>
     <%= builder.text_field :title %>
     <%= builder.fields_for :questions do |question| %>
        <%=  question.text_field :content%>
     <% end %>
  <% end %>
  <p><%= f.submit "Submit" %></p>
<% end %>

How to handle multiple models in one rails form?

2 Answers2

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