problem with one-to-many mapping

priyam · **Joined:** Tue Dec 02, 2003 1:08 pm **Posts:** 5

Hi,

I'm sorry if this is something very obvious, but I've been trying to insert some data into PostGreSQL using Hibernate and it has not been working so far. I'm using Hibernate 2.1rc1.

I have 2 classes Molecule, Atom

Code:

public class Molecule {
// attributes

private List atoms;

//getter/setter methods
}

public class Atom {
// attributes
//getter/setter methods
}

The association between the two is unidirectional. My mapping documents are as follows:

Code:

<class name="Molecule" table="MOLECULE" discriminator-value="M">
<id name="id" column="molecule_id" type="long">
   <generator class="sequence"/>
</id>
<property name="commonName" column="common_name" type="java.lang.String"/>
<property name="molecularFormula" column="molecular_formula" type="java.lang.String" not-null="true"/>
<bag name="atoms" cascade="save-update" lazy="true">
    <key column="molecule_id"/>
    <one-to-many class="cseo.db.chemical.Atom"/>
</bag>
</class>

<class name="Atom"  table="ATOM" discriminator-value="A">
<id name="id" column="atom_id" type="long" unsaved-value="null">
    <generator class="sequence"/>
</id>
<property name="atomicNo" column="atomic_number" type="int" not-null="true"/>
<property name="charge" column="charge" type="double" not-null="true"/>
</class>

Now when I try to insert into the database I get the following exception:

Hibernate: select nextval ('hibernate_sequence')
Hibernate: select nextval ('hibernate_sequence')
Hibernate: insert into MOLECULE (common_name, molecular_formula, molecule_id) values (?, ?, ?)
Hibernate: insert into ATOM (atomic_number, charge, atom_id) values (?, ?, ?)
Hibernate: update ATOM set molecule_id=? where atom_id=?
net.sf.hibernate.HibernateException: Batch update row count wrong: 0 at net.sf.hibernate.impl.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:65)
at net.sf.hibernate.impl.BatcherImpl.executeBatch(BatcherImpl.java:118)
at net.sf.hibernate.impl.BatcherImpl.prepareStatement(BatcherImpl.java:55)
at net.sf.hibernate.impl.BatcherImpl.prepareBatchStatement(BatcherImpl.java:105)
at net.sf.hibernate.collection.AbstractCollectionPersister.recreate(AbstractCollectionPersister.java:537)
at net.sf.hibernate.impl.ScheduledCollectionRecreate.execute(ScheduledCollectionRecreate.java:23)
at net.sf.hibernate.impl.SessionImpl.executeAll(SessionImpl.java:2303)
at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2260)
at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2182)
at net.sf.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:61)

Could anyone please let me know what I am doing wrong? Thanks in advance,

Priya

micho2001 · **Posted:** Thu Dec 04, 2003 3:56 pm

try unsaved-value=0 , instead of null for both atom and molecule

priyam · **Joined:** Tue Dec 02, 2003 1:08 pm **Posts:** 5

Thanks for the reply! Just tried that, it doesnt work. I still get the same exception.

Priya

dimas · **Posted:** Thu Dec 04, 2003 4:12 pm

Take a look at documentation Parent/Child relationship "8.2. Bidirectional one to many".

emmanuel · **Posted:** Thu Dec 04, 2003 6:38 pm

Remove discriminator, these are not super classes.
try hibernate.jdbc.batch_size=0 and see what happen.

Show the between openSession() and session.close()

priyam · **Joined:** Tue Dec 02, 2003 1:08 pm **Posts:** 5

Hi,

I wasnt able to get to this until now, and I tried the

Code:

hibernate.jdbc.batch_size=0

and I dont get the error anymore. But, what I do get is

Hibernate: select nextval ('hibernate_sequence')
Hibernate: select nextval ('hibernate_sequence')
Hibernate: insert into MOLECULE (common_name, molecular_formula, molecule_id) values (?, ?, ?)
Hibernate: insert into ATOM (atomic_number, atom_id) values (?, ?)
Hibernate: update ATOM set molecule_id=? where atom_id=?
net.sf.hibernate.HibernateException: SQL update or deletion failed (row not found)
at net.sf.hibernate.impl.NonBatchingBatcher.addToBatch(NonBatchingBatcher.java:25)
at net.sf.hibernate.collection.AbstractCollectionPersister.recreate(AbstractCollectionPersister.java:540)
at net.sf.hibernate.impl.ScheduledCollectionRecreate.execute(ScheduledCollectionRecreate.java:23)
at net.sf.hibernate.impl.SessionImpl.executeAll(SessionImpl.java:2303)
at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2260)
at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2182)
at net.sf.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:61)

which I think makes sense as the object hasnt yet been committed and so it cannot update it. Is it possible to persist collection relationships like this without having to save the objects in the collection explicitly first? I would like to leave all this to Hibernate as my actual molecule and atom objects are very complicated each containing 2 or more lists of other objects.

The code between openSession() and session.close() is as follows

Code:

session = sessionFactory.openSession();
transaction = session.beginTransaction();
session.save(_molecule);
transaction.commit();
session.close();

Thanks,
Priya

emmanuel · **Posted:** Tue Dec 16, 2003 5:07 am

It has not been commited but it has been executed into the db (2 inserts can be seen). Check the values inserted by setting log mode to debug for net.sf.hibernate.type