Advanced to_xml.rb

# Advanced to_xml
#
# Alex MacCaw
# info@eribium.org
#
# Provide to_xml support to things like strings,
# so you can now actually do ['foo'].to_xml without
# it throwing an exception.
#
# One gotcha to look out for is Rails calls
# to_xml in the render method, so:
#
#   render :xml => {:foo => 'bar'}.to_xml(:title => 'widget')
#
# produces:
#
#  <?xml version="1.0" encoding="UTF-8"?>
#   <string>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
#    &lt;hash&gt;
#    &lt;foo&gt;bar&lt;/foo&gt;
#    &lt;/hash&gt;
#   </string>
#
# The solution is to bypass Rails' magic:
#
#   render :text => {:foo => 'bar'}.to_xml(:title => 'widget'), 
#     :content_type => Mime::XML
#

module ActiveSupport #:nodoc:
  module CoreExtensions #:nodoc:
    module SimpleType
      def to_xml(options = {})
        options[:indent] ||= 2
        options.reverse_merge!({ :builder => Builder::XmlMarkup.new(:indent => options[:indent]),
                                 :root => self.class.to_s.underscore })
  
        options[:builder].instruct! unless options.delete(:skip_instruct)
        
        dasherize = !options.has_key?(:dasherize) || options[:dasherize]
        root = dasherize ? options[:root].to_s.dasherize : options[:root].to_s

        type_name = Hash::Conversions::XML_TYPE_NAMES[self.class.name]

        attributes = options[:skip_types] || self.nil? || type_name.nil? ? { } : { :type => type_name }
        if self.nil?
          attributes[:nil] = true
        end

        options[:builder].tag!(root,
          Hash::Conversions::XML_FORMATTING[type_name] ? Hash::Conversions::XML_FORMATTING[type_name].call(self) : self,
          attributes
        )
      end
    end
  end
end

[NilClass, String, Numeric, Date, Time, TrueClass, FalseClass].each do |cls|
  cls.class_eval do
    include ActiveSupport::CoreExtensions::SimpleType
  end
end