I have a use case I'm having trouble finding documentation for. I would like to generate a natural id when an object is saved to the database for the first time. The object has three ids, a sequential integer surrogate id generated by the database that is used in joins (the primary key), a uuid intended for collating data between separate installations of the system and a short, randomly generated hexidecimal string that is exposed to users.

It would be convenient to be able to do something like the following in the case of the uuid:



I understand the equivalent can be achieved through a trigger or by setting the relevant setter on the object before it is persisted. I've also come accross a reference in one of the FAQs to writing a CompositeUserType and then defining a custom IdentifierGenerator (I assume the custom IdentifierGenerator isn't relevant here).

There is an open issue for a related feature concerning allowing a generator in a composite id element.

http://opensource.atlassian.com/project ... e/HHH-2060

What is a good practice in the above use case? Am I missing something in trying to do things this way?

Thanks in advance for any help.

Eric

Hibernate version: Hibernate 3.2

Hi Eric,
Just curious how you were able to solve this problem. Can you please post the details here? . I'm running into the very same issue.

Can we have the PK class independent of the class to be persisted.

In my case I had some pretty complex custom SQL that I needed to use, and I was getting CGLIB exceptions. I didn't have time to wade through the documentation and the Hibernate code to figure out whether the error was mine or a bug in Hibernate (I assume it was my own error). I needed to move forward, so I removed Hibernate.

Before I got to that point, I found a class called RandomGUID that generates a pseudo-random (rather than purely timestamp-based) guid. When I created a new object I called this class to generate the guid before persisting the object to the store for the first time.

http://javaexchange.com/aboutRandomGUID.html

Hope this helps.