Threaded Comments are not working for me.

Question

Hello, my website has the ability for users to post top level comments successfully, but I am having much trouble with comment children. I am using polymorphic associations, so the comment model can apply to Articles, Profiles, and Pictures. In each of the three cases, the comment will see the model as "commentable".

I want to create a reply link next to each individual comment which passes in the "id" of that particular comment into the comments "new" view page. Then I want the comments "create" method to use that id, @top_level_comment = Comment.find(id), and make a new child using the parameters that the user specified in the "new" comment view, @top_level_comment.children.create(params[:comment]), but I do not know how to put it into code.

So, the user will start on an article show page, which has the following controller:

  def show
    @article = Article.find(params[:id])
    @commentable = Article.find(params[:id])
    @comments = @commentable.comments
    @comment = Comment.new
    @title = @article.title
  end

Then, he will scroll down to the comments on the bottom, and see that there is a reply link via the article show page:

<div id="comment <%= comment.id %>">
  <%= comment.title %>
  | <%= link_to "Permalink", polymorphic_path([@commentable, comment]), :action => :show %>
  | <%= link_to "Reply", polymorphic_path([@commentable, @comment]), :action => :new %>
  | <%= link_to "Edit Comment", polymorphic_path([@commentable, comment]), :action => :edit %>
  | <%= link_to 'Delete Comment', [[@commentable, comment]], :confirm => "Are you sure?", :method => :delete %><br />
  <%= comment.content %><br />
  <%= comment.user.name %><br />
  <%= @comment.children.count %><br /><br />
  <%= render :partial => 'shared/comment', :collection => @comment.children %>

</div>

It is this line in particular where I am having problems:

| <%= link_to "Reply", polymorphic_path([@commentable, @comment]), :action => :new %>

How do I change this to do what I want to do from the description at the top of this post? The polymorphic path does not work. I think it does not work because commentable only works with Articles, Profiles, and Pictures, but not comments. How do I change the path, so it goes to the comments "new" page while passing on the id of the current comment(comment.id)?

Also, my form for adding new comments looks like this:

<%= form_for([@commentable, @comment]) do |f| %>
  <%#= render 'shared/error_messages', :object => f.object %>
  <div class="field">
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </div>
  <div class="field">
    <%= f.label :content %><br />
    <%= f.text_area :content %>
  </div>
  <div class="actions">
    <%= f.submit "Post Comment" %>
  </div>
<% end %>

Here is what the routing looks like:

  resources :articles do
    resources :comments
  end

Hello, when I follow mark's routing, I get this when I try to view an article:

No route matches {:controller=>"comments", :action=>"create", :article_id=>#<Article id: 300, title: "Filler Title", content: "Sunt sit est incidunt et.", user_id: 6, created_at: "2010-09-08 17:42:10", updated_at: "2010-09-08 17:42:10">}

Added the following new info on September 16, 3:48 PST:

Here's the form that allows the user to comment on a commentable, but it does not work when the @commentable is a comment.

1: <%= form_for([@commentable, @comment]) do |f| %>
2:   <%#= render 'shared/error_messages', :object => f.object %>
3:   <div class="field">
4:     <%= f.label :title %><br />

comments controller "new"

  def new
    @commentable = find_commentable
    @comment = Comment.new
  end

When replying to a comment, it goes to the above, but it does not know what @commentable is, so its value is nil when replying to a comment. How do I make it so that @commentable is the @comment from which the user pressed reply from? Here is the link that allows the user to reply to a comment:

  | <%= link_to "Reply", new_comment_path(comment.children.new) %>

Thank you very much.

Answer 1

Surely if you're using polymorphic relationship commentable with comments you should define a self referential polymorphic relationship between comment and comments ie. a comment has many comments as commentable.

Then this:

<%= link_to "Reply", [@comment, @comment.comments.new] %>

#routes.rb

map.resources :comments, :articles, :profiles, :pictures do |commentable|
  commentable.resources :comments, :only => [:new, :create]
end