Using helpers in model: how do I include helper dependencies?

I'm writing a model that handles user input from a text area. Following the advice from http://blog.caboo.se/articles/2008/8/25/sanitize-your-users-html-input, I'm cleaning up the input in the model before saving to database, using the before_validate callback.

The relevant parts of my model look like this:

include ActionView::Helpers::SanitizeHelper

class Post < ActiveRecord::Base {
  before_validation :clean_input

  ...

  protected

  def clean_input
    self.input = sanitize(self.input, :tags => %w(b i u))
  end
end

Needless to say, this doesn't work. I get the following error when I try and save a new Post.

undefined method `white_list_sanitizer' for #<Class:0xdeadbeef>

Apparently, SanitizeHelper creates an instance of HTML::WhiteListSanitizer, but when I mix it into my model it can't find HTML::WhiteListSanitizer. Why? What can I do about this to fix it?

Just change the first line as follows :

include ActionView::Helpers

that will make it works.

UPDATE: For Rails 3 use:

ActionController::Base.helpers.sanitize(str)

Credit goes to lornc's answer

This gives you just the helper method without the side effects of loading every ActionView::Helpers method into your model:

ActionController::Base.helpers.sanitize(str)

This works better for me:

Simple:

ApplicationController.helpers.my_helper_method

Advance:

class HelperProxy < ActionView::Base
  include ApplicationController.master_helper_module

  def current_user
    #let helpers act like we're a guest
    nil
  end       
  
  def self.instance
    @instance ||= new
  end
end

Source: http://makandracards.com/makandra/1307-how-to-use-helper-methods-inside-a-model

To access helpers from your own controllers, just use:

OrdersController.helpers.order_number(@order)

If you want to use a the my_helper_method inside a model, you can write:

ApplicationController.helpers.my_helper_method

I wouldn't recommend any of these methods. Instead, put it within its own namespace.

class Post < ActiveRecord::Base
  def clean_input
    self.input = Helpers.sanitize(self.input, :tags => %w(b i u))
  end

  module Helpers
    extend ActionView::Helpers::SanitizeHelper
  end
end