Rails 4 -Nested Models and Simple Form partial - ruby-on-rails

Question

I am trying to make an app in Rails 4.
I have a projects, project questions and a project answers model.
my models
class Project
has_many :project_questions, dependent: :destroy#, through: :projects
accepts_nested_attributes_for :project_questions
end
class ProjectQuestions
belongs_to :project#, counter_cache: true
has_many :project_answers, dependent: :destroy
belongs_to :user
accepts_nested_attributes_for :project_answers
end
class ProjectAnswer
belongs_to :project_question#, counter_cache: true
belongs_to :user
end
routes.rb
resources :projects do
# patch '/toggle-draft', to 'projects#toggle_draft', as: 'toggle_draft'
resources :project_questions do
resources :project_answers
end
end
In my projects_controller, I have permitted params for project questions and answers as follows:
project_question_attributes: [:title, :content, :user_id, :project_id,
project_answer_attributes: [:answer, :project_question_id]],
These params are also permitted in the Project questions and project answers controllers.
In my projects view, I want to render a partial that I have made in my project_questions view folder.
projects/show
<%= link_to 'Ask a question', new_project_question_path %> <% end %>
<%= render 'project_questions/pqps' %>
In my project_questions partial which is called _pqps, I have;
<div class="containerfluid">
<div class="row">
<div class="col-md-10 col-md-offset-1">
<% f.simple_fields_for :project_questions, #project.project_questions.build do |f| %>
<div class="categorytitle">
<%= f.title %>
</div>
<div class="generaltext">
<%= f.content %>
</div>
<%= render 'project_answers/show' %>
<span class="editproject"> <% if current_user.id == #project.creator_id %>
<%= link_to 'Answer this question', new_project_answer_path %>
<% end %>
</span>
<% end %>
</div>
</div>
</div>
When I try this, I get an error that says:
undefined local variable or method `f' for #<#:0x0000010a11ce60>
I thought I was defining f at the beginning of the opening line of the _pqps form.
I'm really struggling to get a grip with coding. Can anyone see what I've done wrong?

Answer 1

You use f.simple_fields_for in pqps, but f is not defined anywhere.
You have to define it using simple_form_for somewhere. I don't know exactly where – it depends on your own needs, but if, say, the whole form is inside _pqps:
<div class="containerfluid">
<div class="row">
<div class="col-md-10 col-md-offset-1">
<%= simple_form_for #project do |f| %>
<% f.simple_fields_for :project_questions, #project.project_questions.build do |f| %>
# ...
<% end %>
<% end %>
</div>
</div>
</div>
If form "starts" outside "_pqps" partial, then you have to pass f as a local parameter:
<%= render 'project_questions/pqps', f: f %>

Answer 2

projects_controller
def show
#project_questions = #project.project_questions.build
end
View
<%= simple_form_for #project_questions do |f| %>
<%= f.input :title%>
<%= f.input :content %>
<%= f.button :submit %>
<% end %>