Example of using post_save method with xml-mapping gem

institution_mapping.rb

class InstitutionLogin
  include XML::Mapping
  # added namespaces to make root element compliant with recipients's expectation
  def post_save xml, options={:mapping=>:_default}
    xml.root.add_attributes("xmlns"=>"http://schema.intuit.com/platform/fdatafeed/institutionlogin/v1")
    xml.root.add_namespace "xsi", "http://www.w3.org/2001/XMLSchema-instance"
    xml.root.add_namespace "xsd", "http://www.w3.org/2001/XMLSchema"
  end
  self.root_element_name "InstitutionLogin"
  object_node :credentials, "credentials", :default_value => nil
  object_node :challenge_responses, "challengeResponses", :default_value => nil
end