rails nested form with has_many :through relationship - ruby-on-rails

Question

Here are my models:
class Project < ActiveRecord::Base
has_many :project_applications
has_many :questions
accepts_nested_attributes_for :questions, :allow_destroy => true, :reject_if => proc { |a| a[:content].blank? }
end
class Question < ActiveRecord::Base
belongs_to :project
has_many :answers
has_many :project_applications, through: :answers
end
class Answer < ActiveRecord::Base
belongs_to :question
belongs_to :project_application
end
class ProjectApplication < ActiveRecord::Base
belongs_to :project
belongs_to :student
has_many :answers
has_many :questions, through: :answers
end
A project is created by an employer, and a student can create a project_application. The project_application should present the questions and then show form fields that correspond to the questions answers. I cannot for the life of me figure out how the form view should look. I need a form_for ProjectApplication that accepts nested attributes for answers. I have the following in my controller:
class ProjectApplicationsController < ApplicationController
def new
#project = Project.find(params[:project_id])
#project_application = ProjectApplication.new
#project_application.project = #project
#project_application.project.questions.each do |question|
#answer = question.answers.build
#answer.project_application = #project_application #this line does not work
puts 'answer' + #answer.inspect.to_s
end
puts 'here are the answers' + #project_application.answers.inspect.to_s
end
end
The problem with this is that the answers are not correctly being associated with project_applications because the project_applications don't have an id yet (because they have not been created) so the association can't happen, so the answer fields are not displayed. Here is the view code (does not work) that I have now:
<%= form_for #project_application, url: project_project_applications_path(#project.id), method: :post, remote: true do |f| %>
<%= f.fields_for :project do |proj| %>
<%= proj.fields_for :questions do |quest| %>
<%= quest.fields_for :answers do |answer| %>
<%= answer.text_area :content %>
<% end %>
<% end %>
<% end %>
<%= f.submit "APPLY" %>
<% end %>
How do I change the view and/or controller to properly display answer fields correctly associated with questions and the project application?

Answer 1

My understanding:
You have projects
Each project has many questions & project_applications
Each question belongs to a project, has many answers through project_applications
For each project, you'd like to create applications with the applicable answers. Here's what I'd do:
Models
class Project < ActiveRecord::Base
has_many :project_applications
has_many :questions
end
class Question < ActiveRecord::Base
belongs_to :project
has_many :answers
has_many :project_applications, through: :answers
end
class Answer < ActiveRecord::Base
belongs_to :question
belongs_to :project_application
end
class ProjectApplication < ActiveRecord::Base
belongs_to :project
belongs_to :student
has_many :answers
has_many :questions, through: :project
accepts_nested_attributes_for :answers
def self.build
application = self.new
application.answers.build
end
end
Controller
#app/controllers/project_applications_controller.rb
def new
#projectapplication = ProjectApplication.build
#project = #projectapplication.project
end
def create
end
private
def application_params
params.require(:project_application).permit(:application, :attributes, :here, answer_attributes: [:content])
end
Views
#app/views/project_applications/new.html.erb
<%= form_for #projectapplication do |f| %>
<%= f.text_field :application_fields %>
<% #project.questions.each do |question| %>
<%= f.fields_for :answers, question do |answer| %>
<%= answer.hidden_field :question_id, question.id %>
<%= answer.text_field :content, placeholder: question.content %>
<% end %>
<% end %>
<% end %>
Process
This works by creating a new project_application, sending answers directly to the answer model. Because answers are directly associated with questions, and projectsthrough questions, you should be able to get it working without passing any more data
This might not work outright, but I'm sure with some tweaking it will deliver the desired result