I've been learning Rails for about 6 weeks now, so still a noob!

I'm following Ryan Bates screencast on Polymorphic Associations, but I'm getting a "No Route Matches" error when navigating to /model/xx/comments.

After two days going round in circles with this I'm totally stumped—everything appears to be in place.

Comments model:

```
create_table "comments", :force => true do |t|
t.text     "content"
t.integer  "user_id"
t.integer  "commentable_id"
t.string   "commentable_type"
t.datetime "created_at"
t.datetime "updated_at"
end

```

Comments class:

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

```

Other models class:

```
class ModelName < ActiveRecord::Base
has_many :comments, :as => :commentable 
end

```

Routes.rb

```
resources :modelname, :has_many => :comments

```

comments\_controller.rb

```
def index
@commentable = find_commentable  
@comments = @commentable.comments
end

private

  def find_commentable 
    params.each do |name, value|  
        if name =~ /(.+)_id$/  
            return $1.classify.constantize.find(value)  
        end  
    end  
    nil  
  end

```

This all according to the tutorial, but nonetheless is returning "no route matches".

I have tried alternative formatting of the routes as nested resources.

```
resources :modelname do |modelname|
  modelname.resources :comments
end

```

Explicitly defining comments in routes.rb

```
resources :comments

```

And various combinations of terms in routes.rb

```
resources :modelname, :has_many => :commentables

```

or

```
resources :modelname, :has_many => :comments

```

or

```
resources :modelname, :has_many => :comments, :through => :commentable

```

all without success.

Has anyone else encountered this? I'm lost as to where to begin looking.

Many thanks