Add XML::Utils module

lib/calligraphy.rb

@@ -3,6 +3,8 @@ require 'calligraphy/web_dav_request'
 require 'calligraphy/xml/builder'
 require 'calligraphy/xml/namespace'
 require 'calligraphy/xml/node'
+require 'calligraphy/xml/utils'
 
 module Calligraphy
+  DAV_NS = 'DAV:'
 end

lib/calligraphy/xml/utils.rb

@@ -0,0 +1,18 @@
+module Calligraphy::XML
+  module Utils
+    def xml_for(body:, node:)
+      xml = Nokogiri::XML body
+      return :bad_request unless xml.errors.empty?
+
+      namespace = nil
+      xml.root.namespace_definitions.each do |n|
+        namespace = "#{n.prefix}|" if n&.href == Calligraphy::DAV_NS && !n.prefix.nil?
+      end
+      namespace
+
+      node = node.split(' ').map! { |n| namespace + n }.join(' ') if namespace
+
+      xml.css(node).children
+    end
+  end
+end