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Hibernate version:
3.2

Mapping documents:
NA

Code between sessionFactory.openSession() and session.close():
NA

Full stack trace of any exception that occurs:
NA

Name and version of the database you are using:
mysql 5.0.41

The generated SQL (show_sql=true):
NA

Debug level Hibernate log excerpt:
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Problems with Session and transaction handling?

Read this: http://hibernate.org/42.html


Hi guys,

I have a requirement that I'm finding hard to design an implementation for. The requirement is to be able to copy an existing object graph and save new one from the copy. What's making it quite difficult is that some of the Objects in the graph need to be saved as new objects but others need to remain as references to existing objects.

An analogy:

Clone an Order and add a new customer to it. I want a new Order object and a new Customer Object but I want all the references to product to remain as references to the products rather than create new ones.

Completely stuck on this one any help greatly appreciated.

After you you load an existing graph you could set all ids of the objects you wish to be created to 0 (or your equivalent value for unsaved objects). Then you save your root object. If you have cascading enabled in your graph (CascadeType.PERSIST), hibernate will insert the new ones.

Thanks for the quick reply. I had tried to change the Ids but hibernate threw and Exception because i was trying to change teh ID of an object still associated with a session.

It's given me an idea though, I'll try doing a deep copy then changing the IDs as you suggested. One thing I don't know how to do though is change the cascade type either for a specific Object or a specific time i.e. change it then change it back. Is this possible?


Thanks again :-)

Sorry, I don't understand what you mean. Can you explain? Maybe you could post your mapping and your use-case.[/code][/url]

I'm actually using annotations so I assume I'm going to have to



for each getter or relationship

Yes, for example. Or CascadeType.PERSIST.

Hmmmm,

So everything seems ok until my code tries to do a get that returns a Set. I have set the Cascade. When I debug and look at the Objects taht are referecned, everything that is a single Object is ok, but if it is a one to many the get returns the Set but it's empty.

When you debug it is possibly empty, because it has not been loaded lazily, yet. Have you tried to invoke the getter-method? If you pasted your complete mapping and test-case it would be much easier to help.

Setting the fetch type to eager on one to many relationships solved that problem. Now I have another one :-(. when I try to persist I get



No stack trace, which would help me a lot.
I've removed all session flushes from my save methods in my DAOs but I'm still getting the same problem.

Oh and I'm not deleting anything as it says here, http://www.hibernate.org/117.html#A26

Did you set the ids to 0 after you detached the objects or before you did it? you should do it after detaching it.

Could you paste your code, where you try to copy your entities?

Commented out stuff is stuff I've tried that didn't work either, do you know of any documentation on this anywhere??