Finding routes within nested resource in Rails - ruby-on-rails

Question

I am wondering how to access routes in nested resources in rails. I added categories and it as broken my application.
Routes:
resources :categories do
resources :posts do
resources :comments
end
end
It errors out in this:
<% #posts.each_with_index do |post, index| %>
<%= link_to post do %> # originally, this used to work but now it says 'undefined method "post_path"'
<li class="post-title"><%= truncate post.title, length: 50 %></li>
<li class="post-content"><%= truncate post.content, length: 400 %></li>
<li><span class="post-comments"><%= post.comments.count %> comments</span></li>
<% end %>
My root is set to posts#index and has a listing of posts. However, the route nesting (originally I didn't have categories) has broken the routes.
Running rake routes I get in part this:
category_posts GET /categories/:category_id/posts(.:format) posts#index
POST /categories/:category_id/posts(.:format) posts#create
new_category_post GET /categories/:category_id/posts/new(.:format) posts#new
edit_category_post GET /categories/:category_id/posts/:id/edit(.:format) posts#edit
category_post GET /categories/:category_id/posts/:id(.:format) posts#show
PATCH /categories/:category_id/posts/:id(.:format) posts#update
PUT /categories/:category_id/posts/:id(.:format) posts#update
DELETE /categories/:category_id/posts/:id(.:format) posts#destroy
How can I adjust routes to compensate for nesting? Or is there a better way to nest?

Answer 1

You'd need to define another block that nests posts under category resource:
# Existing
resources :posts do
resources :comments
end
# Additional block
resources :categories do
resources :posts do
resources :comments
end
end
With the additional block, your existing routes remain unchanged so existing routes don't break!
It is always better to restrict the routes to only what you need/use. For example if you only need /categories/:category_id/posts, i.e. just the index method on the posts_controller, then your route will be updated to:
resources :categories do
resources :posts, only: [ :index ]
end
This way you have more control on your routes and greater maintainability of the application.

Answer 2

vee's answer is correct if you want to use the nested routes and still preserve the original URLs. This is recommend this if your site is live and changing the URLs would affect links to your indexed pages.
Otherwise, you should point your links to the nested resource, like this:
<%= link_to post.title, [post.category, post] %>
See: Rails - link_to, routes and nested resources