如何获得Nokogiri对象图以递归序列化

Question

我在Rails 3中使用ROXML和Nokogiri进行XML/Ruby对象映射，并且在正确将Ruby对象图映射到XML时遇到问题。

假设以下3个类:

class AnyRequestByRequestData
  include ROXML
  xml_name :anyRequestByRequestData
  xml_accessor :request_data
  xml_accessor :result_level_configuration
  xml_accessor :result_level_constraint, :from => :resultLevelConstraint
  xml_accessor :result_format
end
class ResultLevelConstraint
  include ROXML
  xml_name :resultLevelConstraint
  xml_accessor :result_level_constraint_items, :as => [ResultLevelConstraintItem], :in => :resultLevelConstraintItems
end
class ResultLevelConstraintItem
  include ROXML
  xml_name :resultLevelConstraintItem
  xml_accessor :result_level_configuration_item, :from => "@resultLevelConfigurationItem"
  xml_accessor :offset
  xml_accessor :limit
end

让我们实例化它们:

a = AnyRequestByRequestData.new
b = ResultLevelConstraint.new
c = ResultLevelConstraintItem.new
c.result_level_configuration_item = 1
c.offset = 0
c.limit = 10
b.result_level_constraint_items = [c]
a.result_level_constraint = b

调用 xml = a.to_xml 的回报:

#<Nokogiri::XML::Element:0xb2107e name="anyRequestByRequestData" children=[#<Nokogiri::XML::Element:0xb20eee name="resultLevelConstraint" children=[#<Nokogiri::XML::Text:0xb208fe "#<ResultLevelConstraint:0x226143c>">]>]>

调用 xml。serialize:save_with => 0返回:

<anyRequestByRequestData><resultLevelConstraint>#&lt;ResultLevelConstraint:0x226143c&gt;</resultLevelConstraint></anyRequestByRequestData>

所以，这里发生的是对象ResultLevelConstraint没有被正确序列化。

调用 b.to_xml。serialize:save_with => 0返回正确序列化的ResultLevelConstraint对象:

<resultLevelConstraint><resultLevelConstraintItems><resultLevelConstraintItem resultLevelConfigurationItem="1"><offset>0</offset><limit>10</limit></resultLevelConstraintItem></resultLevelConstraintItems></resultLevelConstraint>

然而，这并不能满足我的需要。我有深度对象图，只想调用to_xml。在根对象(本例中为a)上序列化。所以，这里发生的事情是serialize似乎没有被递归调用。

我认为这是一个Nokogiri问题，因为在对象上调用to_xml似乎返回一个正确的Nokogiri对象图。所以Roxml似乎工作得很好…

Answer 1

它只需要AnyRequestByRequestData的xml_accessor中的类型:

xml_accessor :result_level_constraint, :as => ResultLevelConstraint, :from => :resultLevelConstraint