Google App Engine - Change package for a persistent class

My GWT app is deployed on Google App Engine for Java. I have persisted instances of a class in the app engine datastore. Now I want to move that class to a different package, but it leads to problems in deserializing the existing objec开发者_如何学Pythonts.

So, is there a way I can move the class to a new package? I don't mind updating the existing objects if that helps me achieve my goal.

Thanks.

---

This is how I would move my.package.Clazz to my.new.package.Clazz. The basic idea is to do the migration via a third "temporary" class (TempClazz in this case):

• create new class my.package.TempClazz (do NOT simply rename Clazz)

• create a helper method that will read all existing Clazz entities from the datastore, then copy the data into the new TempClazz instance and store the TempClazz entities in the datastore.

• now deploy to GAE and run the helper method to copy your Clazz entities to TempClazz entities.

• if that worked. Delete Clazz-entities.

• next, basically repeat the process, except that this time you actually refactor my.package.Clazz into the new package my.new.package.Clazz. So at this point you will have two classes: my.package.TempClazz and my.new.package.Clazz.

• all that's left to do is again to read TempClazz from the datastore and copy each into a Clazz-entity.

Pretty involved. Maybe someone knows an easier way?