JSON Objects vs Spring Model Objects

I am using standard Spring MVC 3x framework and have my model entities all built up with all the good relational stuff (javax.persistence API)... integrated with my DB.

As the application evolved, we needed to support JSON calls.

Given that I have various relationships mapped out in my Model Entity layer,

(classX->classY as well as classY->classX)

I am wondering what the best practice is in translating some of these model classes to appropriate JSON objects without duplicate re-referencing?

eg: Sample buggy response

{开发者_Python百科"classX":{"id":"1", "classY":{"id":"2", "classX":{"id":"1", "classY":{"id":"2"...

I am contemplating a couple of methodologies I wouldn't mind feedback on...

1. Keep the existing model classes and set the cross relationships to NULL before putting it into my ModelMap so there won't be some form of re-referencing (me thinks its a HACK)

   {"classX":{"id":"1", "classY":{"id":"2", "classX":null}}}
   

2. Recreate JSON classes similar to the existing models without the re-referencing classes (but I think that means they will not be as reusable... since I will end up only having classX->classY and not backwards if I wished to drill the other way for a data response).

   {"jsonClassX": {"id":"1", "jsonClassY":{"id":"2"}}}
   

3. Just simply construct it as standard ModelMap mappings for every controller call. As such no concept of a reusable JSON class, and is dependent on the way the controller constructs and organises the return values. This seems like the easiest, but it means no-reusable code (besides cut and paste)...

   {"x":{"id":"1", "y":{"id":"2"}}} // for controller call 1
   {"y":{"id":"2", "x":{"id":"1"}}} // for controller call 2
   

So those are the options I am juggling with at the moment, and I wouldn't mind getting some feedback and some pointers on how others have done it.

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You should use Jackson to manage your json marshalling. Then you can add annotations to your model object which tell Jackson how to handle this type of relationship. http://wiki.fasterxml.com/JacksonFeatureBiDirReferences is a good reference for how to set up these relationships.