How do I save a form in double nested form? - ruby-on-rails

Question

I have three models: Event, Workout, and Round.
A person can create a event, that includes a workout, and configure number of sets and weights through round.
I am currently using cocoon gem to create a nested form. I am able to use the form and save Event and Workout, however, Round is not being saved.
class Event < ActiveRecord::Base
has_many :workouts, dependent: :destroy
has_many :rounds, :through => :workouts
belongs_to :user
accepts_nested_attributes_for :workouts, :allow_destroy => true
end
class Workout < ActiveRecord::Base
belongs_to :event
has_many :rounds, dependent: :destroy
accepts_nested_attributes_for :rounds, :allow_destroy => true
end
class Round < ActiveRecord::Base
belongs_to :workout
belongs_to :event
end
I currently have my routes set like this.
Rails.application.routes.draw do
devise_for :users
root 'static_pages#index'
resources :events do
resources :workouts do
resources :rounds
end
end
In my controller, this is how I have my new methods.
New Method for Event
def new
#event = current_user.events.new
end
New Method for Workout
def new
#workout = Workout.new
end
New Method for Round
def new
#round = Round.new
end
I currently have the form under Events' view folder. Under show.html.erb of Events view file, I am trying to display Rounds as well by
<% #workout.rounds.each do |round| %>
<%= round.weight %>
<% end %>
But I am getting undefined method for rounds. Is it not possible to display round in Event view?
Thanks for the help!
Edit 1:
Here is my nested forms.
At the top, I have form for Event.
<%= simple_form_for #event do |f| %>
<%= f.input :title %>
<h3>Work Outs</h3>
<div id="workouts">
<%= f.simple_fields_for :workouts do |workout| %>
<%= render 'workout_fields', f: workout %>
<% end %>
<div class="links">
<%= link_to_add_association 'add workout', f, :workouts %>
</div>
</div>
<div class="field">
<%= f.label :start_time %><br>
<%= f.datetime_select :start_time %>
</div>
<div class="field">
<%= f.label :end_time %><br>
<%= f.datetime_select :end_time %>
</div>
<div class="field">
<%= f.label :description %><br>
<%= f.text_area :description %>
</div>
<div class="actions">
<%= f.submit "Create new Workout" %>
</div>
<% end %>
<% end %>
</form>
Then there is a form for Workout
<div class="nested-fields">
<%= f.input :name %>
<div class="rounds">
<%= f.simple_fields_for :rounds, :wrapper => 'inline' do |round| %>
<%= render 'round_fields', f: round %>
<% end %>
<div class="links">
<%= link_to_add_association 'add round', f, :rounds, :render_option => { :wrapper => 'inline' } %>
</div>
</div>
<%= link_to_remove_association "remove workout", f %>
</div>
And finally, I have the form for Round
<div class="nested-fields">
<table class="table round-table">
<tr>
<td>
<% index = 0 %>
<%= f.simple_fields_for :rounds do |round| %>
<%= render 'set_fields', {f: round, index: index} %>
<% index = index + 1 %>
<% end %>
</td>
<td>Previous Weight</td>
<td><%= f.input_field :weight %></td>
<td><%= f.input_field :repetition %></td>
<td><%= link_to_remove_association "remove rounds", f %></td>
</tr>
</table>
</div>
I am able to create round on rails console and save them. But when I use the form on the web, I cannot save them.
EDIT 2
This is currently how I have the event_params and workout_params set-up.
def event_params
params.fetch(:event, {}).permit(:title, :description, :start_time, :end_time, :workouts_attributes => [:id, :name, :category, :_destroy])
end
Then the workout_params:
def workout_params
params.require(:workout).permit(:name, :category, :rounds_attributes => [:id, :weight, :set, :repetition, :_destroy])
end
I am confused why the form would save Event and Workout. But Round always returns an empty array.

Answer 1

Finally solved it!
I had to have an association in the params as well. Double nested association.
def event_params
params.fetch(:event, {}).permit(:title, :description, :start_time, :end_time, :workouts_attributes => [:id, :name, :category, :_destroy])
end
For my event_params, I only had :workouts_attributes. I thought having :rounds_attributes in workout_params would be okay. But I needed to have rounds_attributes in event_params as well.
Fixing it like below fixed the issue.
def event_params
params.fetch(:event, {}).permit(:title, :description, :start_time, :end_time, :workouts_attributes => [:id, :name, :category, :_destroy, :rounds_attributes => [:id, :weight, :set, :repetition, :_destroy]])
end

Answer 2

you already have rounds attribute in Events model (has_many :rounds, :through => :workouts), why not use it?
<% #event.rounds.each do |round|
<%= round.weight %>
<% end %>