class ActiveModel::Errors

def to_xml(options = {})

#
# name must be specified
# name can't be blank
#
#
# =>
person.errors.to_xml
person.errors.add(:name, :not_specified, message: "must be specified")
person.errors.add(:name, :blank, message: "can't be blank")

Returns an xml formatted representation of the Errors hash. 
def to_xml(options = {})
  to_a.to_xml({ root: "errors", skip_types: true }.merge!(options))
end