##controller code
#the trouble is that I have a table called 'categories', it contains categories of tutorials and projects.
#unfortunately, some of these categories conflict.
#the database is set up in an :acts_as_tree method - all tutorial categories belong to "tutorials".
#the primary key id is unique, but the path (url-friendly name) by which I reference these categories is not.
class TutorialsController < ApplicationController
  def list
    #show a list of all tutorials in a category (paginate this)
    categories = Category.find_by_path(params[:path])
    @category = categories.reject{|category| unless category.root.path == "tutorials"; return true; end}
    @tutorials = @category.tutorials
  end
end

#undefined method `reject' for #<Category:0x2b10bd0dc1b0>
#is the new error I get when I attempt to run this code