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POProblem with polymorphic association in Rails
 

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  1. POProblem with polymorphic association in Rails
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    <p>I am trying to follow <a href="http://railscasts.com/episodes/154-polymorphic-association" rel="nofollow noreferrer">Ryan Bates screencast</a> but have an error message. I did the following:</p> <p>1) Create table</p> <pre><code>class CreateComments &lt; ActiveRecord::Migration def self.up create_table :comments do |t| t.references :commentable, :polymorphic =&gt; true </code></pre> <p>2) Setup models</p> <pre><code>class Comment &lt; ActiveRecord::Base belongs_to :commentable, :polymorphic =&gt; true class Product &lt; ActiveRecord::Base has_and_belongs_to_many :categories has_many :comments, :as =&gt; :commentable class Category &lt; ActiveRecord::Base has_and_belongs_to_many :products has_many :comments, :as =&gt; :commentable </code></pre> <p>3) Change controller show action</p> <pre><code>class CategoriesController &lt; ApplicationController def show @category = Category.find_by_permalink(params[:id]) @commentable = @category @comment = Comment.new(:commentable =&gt; @category) end </code></pre> <p>4) Add a form to template views/categories/show.html.erb</p> <pre><code>&lt;% form_for [@commentable, Comment.new] do |f| %&gt; &lt;p&gt; &lt;%= f.label :name %&gt;&lt;br /&gt; &lt;%= f.text_field :name %&gt; &lt;/p&gt; &lt;p&gt; &lt;%= f.label :content %&gt;&lt;br /&gt; &lt;%= f.text_area :content %&gt; &lt;/p&gt; &lt;p&gt; &lt;%= f.submit 'Submit' %&gt; &lt;/p&gt; &lt;% end %&gt; </code></pre> <p>5) After that I get error message by accessing /categories/my-category-permalink</p> <pre><code>NoMethodError in Categories#show undefined method `category_comments_path' for #&lt;ActionView::Base:0x69a9254&gt; </code></pre> <p>Could you help me to understand what I did wrong? In the original screencast Ryan accesses comments by /categories/permalink/comments using nested associations, but I don't need that. I want to write comments directly from my polymorphic objects. Thanks</p>
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    1. COOn the screencast page, Val has posted a link to demo code he corrected: 59. Val Aug 25, 2009 at 10:02 I fixed all bugs and working code you can download from www.rubyf.info/files/polimorphic_work0.zip
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