I wanted to use a helper method in the controller and I found the following trick in http://railscasts.com/episodes/132-helpers-outside-views. In any controller, there is a @template-instance and we can call helper methods like pluralize or strip_tags on it:
class XyController < ApplicationController
@html = ..
@ascii = @template.strip_tags(@html) # call helper method strip_tags
Ryan is not sure if this use is intended, but it's clear, short and with the current rails version it works fine.
Of cause the explicit call with full path
works in the controller like everywhere else.