Extend String to use ActionView's Text Helpers

Author: curtissummers, http://www.csummers.org/index.php/2006/08/07/extend-string-to-use-actionviews-text-helpers/

#ActionView's TextHelper methods are useful, but I often need to use them in my controller or my model. For several of the TextHelper methods that expect a string as input, it makes sense to extend the String class.
#So, if I want to strip HTML tags, auto link any URLs, and then simple format a comment (in that order) before I save it in the database I can do:
class Comment < ActiveRecord::Base
#...

def before_save
self.text = self.text.strip_tags.auto_link.simple_format
end
end

# This method is much cleaner than including ActionView::Helpers::TextHelper in whatever class I'm in and passing the string as an argument to each method.
# Below is the magic code. Since TextHelper is a module, we create a Singleton class to reference the methods, create the wrapper methods in their own module, and finally include that module in the String class. Note that not all TextHelper methods are included–just the ones that make sense. Drop this code into a file and require it in your environment or within a plugin.
# ActionView Text Helpers are great!
# Let's extend the String class to allow us to call
# some of these methods directly on a String.
# Note:
# - cycle-related methods are not included
# - concat is not included
# - pluralize is not included because it is in
# ActiveSupport String extensions already
# (though they differ).
# - markdown requires BlueCloth
# - textilize methods require RedCloth
# Example:
# "<b>coolness</b>".strip_tags -> "coolness"

require 'singleton'

# Singleton to be called in wrapper module
class TextHelperSingleton
include Singleton
include ActionView::Helpers::TextHelper
include ActionView::Helpers::TagHelper #tag_options needed by auto_link
end

# Wrapper module
module MyExtensions #:nodoc:
module CoreExtensions #:nodoc:
module String #:nodoc:
module TextHelper

def auto_link(link = :all, href_options = {}, &block)
TextHelperSingleton.instance.auto_link(self, link, href_options, &block)
end

def excerpt(phrase, radius = 100, excerpt_string = "…")
TextHelperSingleton.instance.excerpt(self, phrase, radius, excerpt_string)
end

def highlight(phrase, highlighter = '<strong class="highlight">\1</strong>')
TextHelperSingleton.instance.highlight(self, phrase, highlighter)
end
begin
require_library_or_gem 'bluecloth'
def markdown
TextHelperSingleton.instance.markdown(self)
end
rescue LoadError
# do nothing. method will be undefined
end
def sanitize
TextHelperSingleton.instance.sanitize(self)
end
def simple_format
TextHelperSingleton.instance.simple_format(self)
end
def strip_tags
TextHelperSingleton.instance.strip_tags(self)
end
begin
require_library_or_gem 'redcloth'
def textilize
TextHelperSingleton.instance.textilize(self)
end
def textilize_without_paragraph
TextHelperSingleton.instance.textilize_without_paragraph(self)
end
rescue LoadError
# do nothing. methods will be undefined
end
def truncate(length = 30, truncate_string = "…")
TextHelperSingleton.instance.truncate(self, length, truncate_string)
end
def word_wrap(line_width = 80)
TextHelperSingleton.instance.word_wrap(self, line_width)
end
end
end
end
end

# extend String with the TextHelper functions
class String #:nodoc:
include MyExtensions::CoreExtensions::String::TextHelper
end