many-to-many mappings deleted on evict

rowej · **Joined:** Thu Apr 22, 2004 6:30 am **Posts:** 4

Hi,

I have a 'service' object which is associated with a set of 'availabilty levels' objects in a many-to-many mapping:

Code:

<set name="availabilityLevels" lazy="false" table="AVAILABILITY_LEVEL" inverse="false" cascade="all" sort="unsorted">
  <key column="SERVICE_FK"/>
  <many-to-many class="com...AvailabilityLevel" column="AVAILABILITY_LEVEL_FK" outer-join="auto"/>
</set>

The following code causes the association between the requested service (identified by PK) and its applicable availability levels to be deleted:

Code:

public Service findServiceByKey(String key) {
  Service service = null;
  try {
    Session session = getSession(); // retrieve a session maintained by ThreadLocal
    Service service = (Service) session.load(Service.class, key); // load the service
    session.evict(service); // evict it from the session - this causes the associations to be deleted!
  }
  catch (HibernateException he) {
    ...
  }

  return service;
}

After this method has been invoked and the transaction in which it was participating has succesfully completed, the associations are gone! Removing the call to evict the object from the session fixes this problem (i.e. the service <-> availability level assocations are maintained), but I'd really like to understand why evicting the service object causes this problem (before I start coding a work-around).

Cheers,
James.

rowej · **Joined:** Thu Apr 22, 2004 6:30 am **Posts:** 4

Sorry, I forgot to mention that I'm using Hibernate version 2.0.2 (if it makes any difference!)

emmanuel · **Posted:** Thu Apr 22, 2004 4:09 pm

You're not showing the right test case.
What I suspect is that you do

Code:

service = session.load(...);
service.getAvailLevel).add(level); //add it
session.evict(service); //removed from the session before any flush so the association is not created

rowej · **Joined:** Thu Apr 22, 2004 6:30 am **Posts:** 4

No, this is the correct test case, i.e. a read-only operation to retrieve a service and its associated availability levels. The associations between the service that is being retrieved and its availability levels already exist. That is, I'm not adding new availability levels, simply querying existing ones.

In an earlier version of the method given, the call that evicts the loaded service object did not exist and everything worked as expected (no associations in the link table were lost). Another developer later added the call to evict the object which caused this funny behaviour.

I understand why the test case that you gave would not work as it is being cached locally and not being given a chance to synchronize with the database. However, I'm at a loss to explain why evicting the 'service' object after it has been loaded for reading would cause this to happen.

Cheers,
James.

emmanuel · **Posted:** Fri Apr 30, 2004 12:12 pm

reproduce in a simple runnable test case.