Re: [eclipselink-users] cloning a JPA entity by using detach

[Tom Ware <tom.ware@xxxxxxxxxx>]

You will probably need to persist your detached objects in an EntityManager 
derived from a new EntityManagerFactory to have this work.

janne postilista wrote:
> Hi,
>
>  I need to create clones of some of my JPA entities, and modify some
> of their fields. My plan was to:
>
> 1. load some JPA entities: o = em.find(Person.class, id);
> 2. detach them with em.detach(o)
> 3. update a few fields and set @Id to null to make JPA create new rows
> instead of updating the old ones
> 4. em.merge(o)
>
> But this fails since I am not allowed to update the @Id field:
>
> Caused by: Exception [EclipseLink-7251] (Eclipse Persistence Services
> - 2.0.1.v20100213-r6600):
> org.eclipse.persistence.exceptions.ValidationException
> Exception Description: The attribute [id] of class [com.bzz.Person] is
> mapped to a primary key column in the database. Updates are
> not allowed.
>         at org.eclipse.persistence.exceptions.ValidationException.primaryKeyUpdateDisallowed(ValidationException.java:2400)
>
> QUESTION: is there any way around this? Is there some JPA -related
> strategy that I could use to conveniently clone JPA entities?
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