Render a post with libxml in Ruby

render_post_with_libxml.rb

class Renderer::Post
  def self.create_doc_xml(root)
    doc = LibXML::XML::Document.new
    doc.encoding = LibXML::XML::Encoding::UTF_8
    doc.root = LibXML::XML::Node.new(root)
    doc
  end

  def self.create_node(name, value=nil, type=nil)
    node = LibXML::XML::Node.new(name)
    node.content = value.to_s unless value.nil?
    LibXML::XML::Attr.new(node, 'type', type) unless type.nil?
    node
  end

  def self.xml(post)
    doc = create_doc_xml('post')
    doc.root << create_node('content', post.content.to_s)
    doc.root << create_node('created-at', post.created_at.iso8601, 'dateTime')
    doc.root << create_node('published', post.published.to_s, 'boolean')

    # author
    doc.root << (author = create_node('author'))
    author << create_node('name', post.author.name.to_s)
    author << create_node('age', post.author.age.to_s, 'integer')
    author << create_node('email', post.author.email.to_s)

    # comments
    doc.root << (comments = create_node('comments', nil, 'array'))
    post.comments.each do |comment|
      comments << (node_comment = create_node('comment'))

      node_comment << create_node('created-at', comment.created_at.iso8601, 'dateTime')
      node_comment << create_node('message', comment.message)

      # user
      node_comment << (user = create_node('user'))
      user << create_node('name', comment.user.name.to_s)
      user << create_node('age', comment.user.age.to_s, 'integer')
      user << create_node('email', comment.user.email.to_s)

      node_comment << create_node('attachment', comment.attachment)
    end

    doc.to_s
  end
end