Hello,

I am new to Hibernate and have to finish and application started with Hibernate 3, Java 1.5 and Tomvat 6.

My problem is that I have an error when I save my object


I think the error is due to the fact that the object (hibernate result) is store in the HTTPSession. After this object is modified and save with the "saveorupdate" method (i get the error here).

Is is the good method the work with Hibernate ?

Thanks in advance.

Yes, the good old HttpSession can play havoc with your entities.

Basically, the problem is that you have two JavaBean instances that represent the same data. One is loaded, I'm guessing by Hibernate, then you put it into the HttpSession, you pull it out of the HttpSession, at which point it is given a new memory location on the JVM, and as such, Hibernate thinks the object is different from the one pulled out of the HibernateSession. When you go to save the one pulled out of the HttpSession, Hibernate thinks its a different object pointing at the same data, and it gets upset.

One way to avoid this might be to override the .equals and .hashcode methods. A better way?

Just put the primary key of the object in the HttpSession, rather than the object. Then, when you need the object, pull it out of the Hibernate Session and update the values of the object as necessary. Not only will this eliminate Session bloat and take advantage of the POJO cached in the Hibernate Session's first level cache.

Take a look at this tutorial on How Hibernate3 Works for more information on persistent objects, detached objects and the NonUniqueObject Exception that you are getting.

http://www.hiberbook.com/HiberBookWeb/learn.jsp?tutorial=07howhibernateworks

Ok, that's what i have done and it's ok now.
Thanks

Lionel

Great! I love it when a Hibernate plan comes together. :)