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I've got a hibernate interfaced mysql database with a load of different types of objects, some of which are periodically retrieved and altered by other pieces of code, which are operating in JADE agents. Because of the way the objects are retrieved (in queries, returning collections of objects) they don't seem to be managed by the entity manager, and definitely aren't managed when they're passed to agents without an entity manager factory or manager.

The objects from the database are passed about between agents, before arriving back at the database, at this point, I want to update the version of the object in the database - but each time I merge the object, it creates a new object in the database.

I'm fairly sure that I'm not using the merge method properly. Can anyone suggest a good way that I can combine the updated object with the existing database object without knowing in advance which properties of the object have changed? Possibly something along the lines of searching for the existing object and deleting it, then adding the new one, but I'm not sure how to do this without messing up PKeys etc

nowaycomputer
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  • How do you pass the object between agents? Are you copying the hibernate ID field of the class? – rambo Sep 05 '11 at 17:59

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Hibernate has saveOrUpdate-method which either saves the object or updates it depending if an object with a same ID already exists:

http://docs.jboss.org/hibernate/core/3.3/reference/en/html/objectstate.html#objectstate-saveorupdate

Happiradikaali
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