员额专栏认为,只有在第一点意见已经形成的情况下,才能增加评论,否则就会造成这种rou错:

No route matches {:action=>"show", :controller=>"posts", :view=>"comments"}

起站:

Started POST "/comments" for 127.0.0.1 at 2011-05-17 18:18:03 -0700
  Processing by CommentsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"BPeNvVJh+dLBhpiZK16phQHp7UV4MasPyQW6PL9VG8I=", "comment"=>{"post_id"=>"", "parent_id"=>"", "name"=>"", "content"=>"yo"}, "commit"=>"Reply"}
AREL (0.9ms)  INSERT INTO "comments" ("name", "content", "post_id", "created_at", "updated_at", "ancestry") VALUES (  ,  yo , NULL,  2011-05-18 01:18:03.445466 ,  2011-05-18 01:18:03.445466 , NULL)
Completed   in 133ms

ActionController::RoutingError (No route matches {:action=>"show", :controller=>"posts", :view=>"comments"}):
  app/controllers/comments_controller.rb:14:in `block (2 levels) in create 
  app/controllers/comments_controller.rb:9:in `create 

如果已经设立第一个职位评论

posts#show:

<%= render @post %>

<%= nested_comments @comments.arrange(:order => :created_at) %>

<%= render "comments/form" %>

the form:

<%= simple_form_for :comment, :url => { :controller => :comments, :action => "create" } do |f| %>
  <%= f.input :post_id, :required => false, :as => :hidden %>
  <%= f.input :parent_id, :required => false, :as => :hidden %>
  <%= f.input :name, :label => false, :placeholder => "Name (optional)", :required => false %>
  <%= f.input :content, :label => false, :placeholder => "Reply", :as => :text %>
  <%= f.button :submit, "Reply" %>
<% end %>

评论控制员:

def new
  @comment = Comment.new(:parent_id => params[:parent_id], :post_id => params[:post_id])
end

def create
  @comment = Comment.create(params[:comment])
  @comment.save
  respond_to do |format|
    format.html do
      if @comment.errors.present?
        render :new
      else
        redirect_to(post_path(@comment.post, :view => "comments"))
      end
    end
    format.js
  end
end

routes:

root :to => "posts#index"
resources :topics
resources :posts
resources :comments

图表:

create_table "comments", :force => true do |t|
  t.string   "name"
  t.text     "content"
  t.integer  "post_id"
  t.datetime "created_at"
  t.datetime "updated_at"
  t.string   "ancestry"
end

add_index "comments", ["ancestry"], :name => "index_comments_on_ancestry"

create_table "posts", :force => true do |t|
  t.string   "name"
  t.string   "title"
  t.text     "content"
  t.integer  "topic_id"
  t.datetime "created_at"
  t.datetime "updated_at"
end

create_table "topics", :force => true do |t|
  t.string   "name"
  t.datetime "created_at"
  t.datetime "updated_at"
end