Question

class CommentsController < ApplicationController

  def create

    @commentable= context_object()
    @comment = @commentable.comments.build(params[:comment].merge(:user_id => current_user.id))

    if @comment.save
      respond_to do |format|
        format.js
      end
    else
      render :action => 'new'
    end
  end

  private  

  def context_object
    params[:constraint][:context_type].singularize.classify.constantize.find( context_id )
  end

  def context_id
    params["#{ params[:constraint][:context_type].singularize }_id"]
  end

end

This commenting module has served me well but I ran into a hitch this morning, possibly because of my use of nested resources. Essentially, I now have a URL like:

/projects/3/albums/6/attachments/84

When I comment on that page, I get the error:

ActiveRecord::RecordNotFound (Couldn't find Project without an ID):
  app/controllers/comments_controller.rb:102:in `context_object'
  app/controllers/comments_controller.rb:14:in `create'

My routes file looks like:

resources :projects do
  resources : albums do
    resources :attachments
  end
end

resources :attachments do
    resources :comments, :only => [:create, :update,:destroy],
              :constraint => {:context_type => "conversations"}
end

Any ideas on how I can get the commenting module to play nicely with commenting on project>Album>Attachment ?

Thanks for the input,

Answer 1

Posting this as an answer in order not to clutter the comments to the original question.

Since you don’t have the requirement to keep attachments available via /attachments – making the second resources block useless, do something like this:

resources :projects do
  resources :albums do
    resources :attachments do
      resources :comments, :only => [:create, :update,:destroy],
                           :constraint => {:context_type => "conversations"}
    end
  end
end

That’s going to change your routes helpers (_path and _url), go through your controller(s) and view(s) and change them to reflect your new helpers.

Specifically, attachment_comments_path becomes project_album_attachment_comments_path.

The full list of routes for those models can be viewed by running rake routes in a console. I’d also recommend you take a closer look to the Rails routing guide.