ルーティングをネストしている時のprefix

routes.rb

#--- 略 ---

 

resources :posts do

    resources :comments

end

 rails routes

prefix	HTTPメソッド	パス	アクション
post_comments	GET	/posts/:post_id/comments(.:format)	comments#index
	POST	/posts/:post_id/comments(.:format)	comments#create
new_post_comment	GET	/posts/:post_id/comments/new(.:format)	comments#new
edit_post_comment	GET	/posts/:post_id/comments/:id/edit(.:format)	comments#edit
post_comment	GET	/posts/:post_id/comments/:id(.:format)	comments#show
	PATCH	/posts/:post_id/comments/:id(.:format)	comments#update
	DELETE	/posts/:post_id/comments/:id(.:format)	comments#destroy

＜例＞showへのページ移動時

パスは「/posts/:post_id/comments/:id(.:format)」

IDの指定が２箇所あるので、引数が２つ必要（どの投稿IDか、どのコメントIDか）

post_comment_path(comment.post.id, comment.id)