Ruby on Rails。多态关联中的视图

Question

我开发的网站，其中有文章和新闻页面，我想添加两个评论的机会。我使用多态关联。

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

我想在可注释对象下面显示注释

视图/文章/show.html.erb

<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' %>

views/news/show.html.erb

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

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

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

视图/评论/_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 %>

和我的控制器：

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

当我转到mysite/文章/1时，我得到了错误: nil:NilClass的未定义方法‘`each’，因为我的文章中没有@commentable，控制器和注释控制器的代码不会执行。

如何在文章/展示页面上执行评论控制器的索引操作？

Answer 1

添加局部变量:commentable => @article，同时呈现注释窗体

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

从分部视图views/commentaries/_form.html.erb访问局部变量

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