Fixing "undefined method white_list_sanitizer' for String:Class" and "undefined method full_sanitizer' for String:Class"
If you get one of these errors, it's highly likely that you've upgraded to Rails 2.2 or higher:
undefined method white_list_sanitizer' for String:Class
undefined method full_sanitizer' for String:Class
The fix is to extend the SanitizeHelper.
class String
extend ActionView::Helpers::SanitizeHelper::ClassMethods
end