Have you tried the following inside comments_controller?
class CommentsController < InheritedResources::Base
before_filter :authenticate_user! # Assuming you are using Devise for authentication
respond_to :html, :xml, :json
belongs_to :project, :finder => :find_by_project_uuid!, :class_name => "Thfz::Project"
def create
@comment = build_resource
@comment.author = current_user
create!
end
end