make the comment(in the rails guide exmple) editable - ruby-on-rails

Question

I am learning rails by following the rails 3 guide.
The blog application have ran now,however I want to make the comment editable,and make the update ,create form both in the post show page. so I make the following modifiation:
post.show.htm.erb:
<h2>Comments</h2>
<% #post.comments.each do |comment| %>
<tr>
<td><%= comment.commenter %></td>
<td><%= comment.body %></td>
<td><%= link_to 'Edit', edit_post_comment_path(#post,comment) %></td>
<td><%= link_to 'Destroy', post_comment_path(#post,comment), confirm: 'Are you sure?', method: :delete %></td>
</tr>
<% end %>
</table>
<h2>Add a comment:</h2>
#here,I can not set the form_for property.
<%= form_for([#post,#comment],:url=>post_comment_path) do |f| %>
<div class="field">
<%= f.label :commenter %><br />
<%= f.text_field :commenter %>
</div>
<div class="field">
<%= f.label :body %><br />
<%= f.text_area :body %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
The controller controller:
class CommentsController < ApplicationController
# GET /posts/1/comments/1/edit
def edit
#render json: params
#post=Post.find(params[:post_id])
#comments=Comment.all
#comment = Comment.find(params[:id])
render "/posts/show"
end
#other action omitted
def show
# I donot know what to do here
end
end
However I can not access the link:
http://localhost:3000/posts/1
I get the error:
No route matches {:action=>"show", :controller=>"comments"}
In fact,as you can see I have the show action in CommentController.
And,I wonder why it will access the comments#show action?
This is my routes:
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
PUT /posts/:post_id/comments/:id(.:format) comments#update
DELETE /posts/:post_id/comments/:id(.:format) comments#destroy
posts GET /posts(.:format) posts#index
POST /posts(.:format) posts#create
new_post GET /posts/new(.:format) posts#new
edit_post GET /posts/:id/edit(.:format) posts#edit
post GET /posts/:id(.:format) posts#show
PUT /posts/:id(.:format) posts#update
DELETE /posts/:id(.:format) posts#destroy
home_index GET /home/index(.:format) home#index
root / home#index
The /posts/:id will trigger posts#show. why comments#show?

Answer 1

if u need to edit the post, then add
def edit
#post = Post.find(params[:id])
end
def update
#post = Post.find(params[:id])
if #post.update_attributes(params[:post])
redirect_to some_path and return
end
render 'edit' #error
end
the form for edit should send a PUT request to the server. rails maps the url and the request ( like GET/POST/PUT/DELETE) using the routes file to the controller actions.
here
PUT /posts/:id(.:format) posts#update
the request is PUT, controller is PostsController and the action is update.
also,
post GET /posts/:id(.:format) posts#show
u need to pass the http request from the form if its POST/PUT/DELETE.
u can do so for 'edit'
<%= form_for([#post,#comment],:url=>post_comment_path, :method => :put) do |f| %>
maps to the show request for PostsController. the format is html bydefault. for more info, have a detailed look at the server log.