Routing Error uninitialized constant Comments – Making Nested comments - ruby-on-rails

Question

I'm learning Rails. I've got an app that has "Ideas", which have "Comments"
I've created the comments using this guide (https://gorails.com/episodes/comments-with-polymorphic-associations)
I am using the 'Ancestry' gem to attempt make them nested using this guide on railscasts (http://railscasts.com/episodes/262-trees-with-ancestry)
Anyways I'm getting this error "ActionController::RoutingError (uninitialized constant Comments):"
This is where I'm getting the error – when I hit the "Reply" link
<h3> Comments </h3>
<% #idea.comments.each do |comment| %>
<div>
<%= comment.body %>
<div class="actions">
<%= link_to "Reply", new_comment_path(:parent_id => comment) %>
</div>
</div>
<% end %>
The above is being rendered on the "Ideas/show.html" page
<p id="notice"><%= notice %></p>
<p>
<strong>Description:</strong>
<%= #idea.description %>
</p>
<%= render partial: "comments/comments", locals: {commentable: #idea} %>
<%= render partial: "comments/form", locals: {commentable: #idea} %>
<% if #idea.user == current_user %>
<%= link_to 'Edit', edit_idea_path(#idea) %>
<% end %>
<%= link_to 'Back', ideas_path %>
I want to send them here to "Comments/new" which is the same as my form page
<%= form_for [commentable, Comment.new] do |f| %>
<div class="form-group">
<%= f.hidden_field :parent_id %>
<%= f.text_area :body, class: "form-control", placeholder: "Add a comment here" %>
</div>
<%= f.submit class: "btn btn-primary" %>
<% end %>
Routes.rb
Rails.application.routes.draw do
resources :ideas do
resources :comments, module: :ideas
end
devise_for :users
root 'ideas#index'
get "about" => "pages#about"
get "new_comment" => "comments/new"
end
Comments_controller.rb
class CommentsController < ApplicationController
before_action :authenticate_user!
def new
#comment = Comment.new(:parent_id => params[:parent_id])
end
def create
#comment = #commentable.comments.new comment_params
#comment.user = current_user
#comment.save
redirect_to #commentable, notice: "Your comment was posted"
end
private
def comment_params
params.require(:comment).permit(:body)
end
end
Ideas_controller.rb
class IdeasController < ApplicationController
before_action :set_idea, only: [:show, :edit, :update, :destroy]
before_action :authenticate_user!, except: [:index, :show]
before_action :correct_user, only: [:edit, :update, :destroy]
respond_to :html
def index
#ideas = Idea.all
end
def show
end
def new
#idea = Idea.new
#idea.comments.build
respond_with(#idea)
end
def edit
end
def create
#idea = current_user.ideas.build(idea_params)
if #idea.save
redirect_to #idea, notice: "Idea was successfully created."
else
render :action => 'new'
end
end
def update
if #idea.update(idea_params)
redirect_to #idea, notice: "Your idea has been updated"
else
render action: 'edit'
end
end
def destroy
#idea.destroy
redirect_to ideas_url
end
private
def set_idea
#idea = Idea.find(params[:id])
end
def correct_user
#idea = current_user.ideas.find_by(id: params[:id])
redirect_to ideas_path, notice: "You can't edit this" if #idea.nil?
end
def idea_params
params.require(:idea).permit(:description)
end
end
Any help would be much appreciated, thank you.
EDIT _ Added my routes
idea_comments GET /ideas/:idea_id/comments(.:format) ideas/comments#index
POST /ideas/:idea_id/comments(.:format) ideas/comments#create
new_idea_comment GET /ideas/:idea_id/comments/new(.:format) ideas/comments#new
edit_idea_comment GET /ideas/:idea_id/comments/:id/edit(.:format) ideas/comments#edit
idea_comment GET /ideas/:idea_id/comments/:id(.:format) ideas/comments#show
PATCH /ideas/:idea_id/comments/:id(.:format) ideas/comments#update
PUT /ideas/:idea_id/comments/:id(.:format) ideas/comments#update
DELETE /ideas/:idea_id/comments/:id(.:format) ideas/comments#destroy
ideas GET /ideas(.:format) ideas#index
POST /ideas(.:format) ideas#create
new_idea GET /ideas/new(.:format) ideas#new
edit_idea GET /ideas/:id/edit(.:format) ideas#edit
idea GET /ideas/:id(.:format) ideas#show
PATCH /ideas/:id(.:format) ideas#update
PUT /ideas/:id(.:format) ideas#update
DELETE /ideas/:id(.:format) ideas#destroy
new_user_session GET /users/sign_in(.:format) devise/sessions#new
user_session POST /users/sign_in(.:format) devise/sessions#create
destroy_user_session DELETE /users/sign_out(.:format) devise/sessions#destroy
user_password POST /users/password(.:format) devise/passwords#create
new_user_password GET /users/password/new(.:format) devise/passwords#new
edit_user_password GET /users/password/edit(.:format) devise/passwords#edit
PATCH /users/password(.:format) devise/passwords#update
PUT /users/password(.:format) devise/passwords#update
cancel_user_registration GET /users/cancel(.:format) devise/registrations#cancel
user_registration POST /users(.:format) devise/registrations#create
new_user_registration GET /users/sign_up(.:format) devise/registrations#new
edit_user_registration GET /users/edit(.:format) devise/registrations#edit
PATCH /users(.:format) devise/registrations#update
PUT /users(.:format) devise/registrations#update
DELETE /users(.:format) devise/registrations#destroy
root GET / ideas#index
about GET /about(.:format) pages#about
new_comment GET /new_comment(.:format) comments/new#new_comment