AhmedNadar PRO said almost 2 years ago on Nested Comments from Scratch :
Thanks for your video. 
I have followed it but I got an error on creating a reply. I'm able to create a comment and delete a reply. 
I get below error header + previous comment when I create a reply. Although when I refresh item show view i see all replies.

NoMethodError at /comments/12/comments
undefined method `comment_url' for #<Comments::CommentsController:0x00000000025e18>
Did you mean?  comment_comment_url

Better_errors request info and instance variables
@_params | #<ActionController::Parameters {"authenticity_token"=>"======", "comment"=>
#<ActionController::Parameters {"content"=>"nice"} permitted: false>, "commit"=>"Create Comment", "controller"=>"comments/comments", "action"=>"create", "comment_id"=>"10"} permitted: false>
@ransack_items | Ransack::Search<class: Item, base: Grouping <combinator: and>>
@commentable | #<Comment id: 10, user_id: nil, commentable_type: "Comment", commentable_id: 9, content: nil, created_at: "-0000", updated_at: "20000">
@current_user | #<User id: 1, email: "admin@gmail.com", created_at: "0000", updated_at: "0000-", first_name: "Admin", last_name: "Man", slug: "admin-man">
@comment | #<Comment id: 12, user_id: 1, commentable_type: "Comment", commentable_id: 10, content: "nice", created_at: "-0000", updated_at: "0000">
Request parameters | {"authenticity_token"=>"=====", "comment"=>{"content"=>"nice"}, "commit"=>"Create Comment", "controller"=>"comments/comments", "action"=>"create", "comment_id"=>"10"}

While I followed your video, I have different setup for items:
@commentable = Item.friendly.find(params[:item_id])

resources :items do
 resources :comments, only: %i[new create destroy], module: :items

What am I missing?