Hello,

I want to map the following situation. I have a table called EDUCATION and a table called SCHOOLS. Between those tables I have an associative table called EDUCATION_SCHOOLS. The (usefull) fields:

EDUCATION:
id (long) - PK
name (varchar)
versionNr (long)

SCHOOLS:
id (long) - PK
name (varchar)
versionNr (long)

EDUCATION_SCHOOLS:
id (long) - PK
education_id (long) (FK to EDUCATION.id)
school_id (long) (FK to SCHOOLS.id)
name (varchar)
versionNr (long)

Their is a Unique Constraint between EDUCATION_SCHOOLS.education_id and EDUCATION_SCHOOLS.school_id.

What I want to be able to do:
EDUCATION: select, update, insert
SCHOOLS: select, update, insert
EDUCATION_SCHOOLS: select, update (only the non-FK fields), insert

I never want to delete anything in those tables. (and it's never ever going to be an option either)

Hibernate version:
Hibernate-Version: 3.0.5

Mapping documents:


Name and version of the database you are using:
Oracle XE 10g


I am able to:
EDUCATION: select, insert, update
SCHOOLS: select, insert, update
EDUCATION_SCHOOLS: select

Problems:
EDUCATION_SCHOOLS: when I try to insert, I sometimes get unique constraint violations. (when I should get them, thus I'm trying to insert something that already exists .. but how do I stop Hibernate from Inserting?)

EDUCATION_SCHOOLS: when I try to update, sometimes it works, but often I get:




As you can see from the stacktrace I use Spring for the transactionManager: org.springframework.orm.hibernate3.HibernateTransactionManager in which I use e sessionFactory: org.springframework.orm.hibernate3.LocalSessionFactoryBean

In my DAO, I try to save with the regular this.getHibernateTemplate().saveOrUpdate that has always worked for me.

Another problem I have:
when i update "name" in EDUCATION, the records with that ID are delete from EDUCATION_SCHOOLS ...


As I am experiencing 3 different problems, I'm pretty sure something is wrong in the mapping files .. however I fail to find out what .. Any input would be greatly appreciated.

(I translated some class/table-names, that's what the ## cause)

Anyone has any ideas?

Hibernate doesn't check constraints. You'll have to write your own code to check if a duplicate exists before you try to insert a new entity.



Are you sure that the Education.getSchools() method is implemented correctly? Eg. it must return the same Set that was passed to Education.setSchools(). It may also help to add inverse="true" to the mapping just as you have done for the Schools.education property.



I am not sure why the stack trace displays Object .... with identifier [null]... I had expected the ID to be shown instead of null if it is an update of an existing entity. Anyway, if your code works some times but not always it is possible that there is actually another transaction that has updated the same record. It's hard to be more precise without seeing any code.

nordborg: thank you for your suggestion.

Concerning the unique constraint violation: I SELECT the record I'm trying to INSERT first in my "save-method". If the records already exists, I don't call saveOrUpdate(). Problem solved.

Concerning the deleted record when updating: I added inverse="TRUE" to education and schools and the delete doesn't happen anymore. I tought I could only inverse one side of the many-to-many. Problem also solved.

I also solved the HibernateOptimisticLockingFailureException. When I try to UPDATE I first select the record with the same EDUCATION_ID and SCHOOL_ID and I add the changed fields to the result of that SELECT. Imho I'm selecting once to much .. but it works, and it works fast.

So, I'm happy man :)

Thnx for your input!