Ruby on Rails。多態協會的意見

Question

我開發的網站有文章和新聞頁面，我想增加評論兩者的機會。我使用多態關聯。

class Article < ActiveRecord::Base 
    has_many :commentaries, :as => :commentable 
end 

class News < ActiveRecord::Base 
    has_many :commentaries, :as => :commentable  
end 

class Commentary < ActiveRecord::Base 
    belongs_to :commentable, :polymorphic => true 
end 

我想顯示下面commentable對象

的意見/用品/ show.html.erb評論

<p> 
    <b>Title:</b> 
    <%= @article.title %> 
</p> 

<p> 
    <b>Short text:</b> 
    <%= @article.short_text %> 
</p> 

<p> 
    <b>Full text:</b> 
    <%= @article.full_text %> 
</p> 

<%= render 'commentaries/form' %> 

的意見/新聞/ show.html.erb

<p> 
    <b>Title:</b> 
    <%= @news.title %> 
</p> 

<p> 
    <b>Text:</b> 
    <%= @news.text %> 
</p> 

<p> 
    <b>Created:</b> 
    <%= @news.created %> 
</p> 

views/commentaries/_form.html.erb

<h1>Comments</h1> 

<ul id="comments"> 
    <% @commentaries.each do |comment| %> 
     <li><%= comment.content %></li> 
    <% end %> 
</ul> 

<h2>New Comment</h2> 
<% form_for [@commentable, Comment.new] do |form| %> 
    <ol class="formList"> 
     <li> 
     <%= form.label :content %> 
     <%= form.text_area :content, :rows => 5 %> 
     </li> 
     <li><%= submit_tag "Add comment" %></li> 
    </ol> 
<% end %> 

我的控制器：

class CommentariesController < ApplicationController 
    def index 
     @commentable = find_commentable 
     @commentaries = @commentable.commentaries 
    end 
end 

class ArticlesController < ApplicationController 
    def show 
    @article = Article.find(params[:id]) 
    end 
end 

當我去的mysite /條/ 1，收到錯誤未定義的方法`每個」近親：NilClass，因爲沒有@commentable在我的文章控制器評論控制器的代碼不會執行。

如何在文章/展示頁面上執行評論控制器的索引動作？

Answer 1

添加本地變量:commentable => @article，而渲染的評論形式

<%= render 'commentaries/form', :commentable => @article %> 

訪問從你的局部變量局部視圖views/commentaries/_form.html.erb

<% commentable.commentaries.each do |comment| %> 
    ... 
<% end %> 
... 
<% form_for [commentable, Comment.new] do |form| %> 
    ... 
<% end %>