Hi I have two methods one to get a persisted object and one to update a certain value of an object, like below

private ClassA getByPrimaryKey( int id )
{
LOGGER.fine( "Looking for ClassA entry with primary key " + id );

ClassA retrieved = null;
Integer primaryKey = new Integer( id );
Session sess = sessionFactory.openSession();
try
{
sess.beginTransaction();
retrieved = ( ClassA )sess.load( ClassA .class, primaryKey );
sess.getTransaction().commit();
}
catch ( Exception e )
{
LOGGER.severe( "Trouble in getByPrimaryKey " + e.getMessage() );
sess.getTransaction().rollback();
}
finally
{
sess.close();
}
return retrieved;
}

/**
* Set the status in the ClassA to an appropriate value
* @param a the ClassA entry to be updated
* @param status The value to set the ClassA's ClassB
*/
private void setTaskStatus( ClassA a, byte status )
{
ClassB b = new ClassB ( status );
Session sess = sessionFactory.openSession();
try
{
sess.beginTransaction();
a.setClassB ( b);
sess.saveOrUpdate( a);
sess.getTransaction().commit();
}
catch ( Exception e )
{
sess.getTransaction().rollback();
LOGGER.severe( "Problem setting ClassB " + e.getMessage() );
}
finally
{
sess.close();
}
}

If I first retrieve a persisted instance then try and update it I get the following error 'Problem setting ClassB could not initialize proxy - the owning Session was closed'
Ive read the documentation regarding persisting detached instances and I seem to being doing as told, I have also read something about lazy initialization, could this be my problem? If so how would I go about fixing it.

Thanks,

M.

Your transactions are too small in scope. You should not be starting and ending a transaction for each method. This is causing your problem. A Sesson only lasts as long as a transaction. When you load a persistent object using a session, then end the transaction, that session is gone, even though the persistent object is still around. When you begin a new transaction with a new session, it isn't aware of the persistent object you loaded into the other session. That is why you are getting the error. The persistent object is detached from the point of view of the new session, so an "update" is not a valid operation for that persistent object.

Hi Mike,

as has been said running all the code in a single transaction would be the easiest way to solve your Problem.
The Problem doesn't occur during the hibernate update-Instruction, it already occurs in the a.setClassB(), since a's old ClassB is a hibernate-proxxy-object (because lazy-loading is enabled) and a is detached in your new session.

If this can't be done you could try reversing the oder of two of your statements:

sess.beginTransaction();
[red]
sess.saveOrUpdate( a);
a.setClassB ( b);
[/red]
sess.getTransaction().commit();

Now you first reattach a to your current session (via saveOrUpdate()) and then access a's ClassB.

Hope this works....

Greets

piet

Thanks for your help guys.