Hi,

is there a chance to let hibernate create the ID at creation-time of an entity?

I´ve got the problem, that I want to share one id between multiple entities while having a unidirectional one-to-one relation.
This way I only have a generated value at the parent-object and for the dependent entities I have to set the id manually (to the same id, as the parent). Unfortunately the id is only generated when persisting the entity (before that the value is null), so it´s hard to propagate an object-reference to the dependant entities (even with @PrePersist as I would have to parse the parent-object).
So what I could do is to manually get the next value from my sequence and set this as an id for every entity. But if the id would be generated when a new entity is created, there won´t be a problem at all. Is there a way to achive this? I already looked at the @Generated-annotation, but this doesn´t seem to solve this issue.

Any input would be greatly appriciated.

Thomas



Hibernate version:
3.3.0

Mapping documents:

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

Full stack trace of any exception that occurs:

Name and version of the database you are using:

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

Now I saw something like this, which seems to go in the same direction:



The question is now: does this also work for a uni-directional relationship or do I have to have a bi-directional relationship for this to work?

Thomas

I've read a few post and it needs to be bi-directional to work, I've tried the same and failed. Read this post, someone was successful with it,

http://opensource.atlassian.com/project ... e/HHH-2712

http://www.i-proving.ca/space/Technolog ... ne+Mapping

http://saloon.javaranch.com/cgi-bin/ubb ... 8&t=002219

Here is a link to my post, of what all I've tried, if you were able to solve the problem, please let me know how were you able to do so. Thanks

http://forum.hibernate.org/viewtopic.ph ... 23#2376623

varunmehta,

thanks for your answer. I didn´t find a solution to this as well until today. So I decided to use bi-directional relations and hope, that there might be a solution some time. But right now it works for me (with a little overhead and a little unnecessary relations)

As you already wrote in your posting, the problem seems to be with the generator annotations. Also in my scenario, when I debug into the code, somehow my parent-object resolves to null when persisting to database and therefor causes an error when trying to get the parent´s id. If I remove the @GenericGenerator-annotation and assign the id manually everything works fine, so I guess there are still some problems when using the @GenericGenerator-annotation anyway

Thomas

I manually assigned the id, removed the GenericGenerator for the class and it worked like the charm. One question though, have you tried it without annotations and using hbm files? Cos that's the next thing I plan to try...

If it's a problem then it might be a bug with the GenericGenerator.

yep, that´s what I did as well.

No I´ve never used hbm-files, because I use hibernate in an EJB3-environment and therefor rely on annotations from javax.persistence (except the @GenericGenerator, because that´s out of specs).

I also think, there is probably a bug in the GenericGenerator.

So much time gone from last reply in this topic. All links above - i already visited. This all not work. Is it possible use Generic generator in children of unidirectional relation? So much time gone. Maybe something change?

Hello!
Thanks for nice shearing....
I am also new in here.