Transactional persistence-modifier

Question

Hi,
I'd like to define a field of a persistent class as "transactional". This
field is not mapped to a table column, but it must be rolled-back when
transaction aborts.
According to JDO specification, I tryed to use the "persistence-modifier"
attribute of the "field" element in jdo metadata, as follows:
<jdo>
<package name="it.tasso.model">
<class name="Indirizzo" objectid-class="IndirizzoId">
<field name="id" primary-key="true"/>
<field name="transazValue" persistence-modifier="transactional"/>
</class>
</package>
</jdo>
But at runtime, when the persistent object is retrieved from the
datastore, the following error occurs:
Exception in thread "main" kodo.jdbc.meta.MappingInfoNotFoundException: No
mapping information was found for "it.tasso.model.Indirizzo.transazValue".
I't obvious that there's no mapping information, because that field is
just transactional. In fact, kodo documentation says:
persistence-modifier: Specifies how JDO should manage the field. Legal
values are persistent for persistent fields, transactional for fields that
are non-persistent but can be rolled back along with the current
transaction,
If the persistence-modifier attribute is set to NONE, no errors occurs.
Where's my mistake?

Answer 1

Patrick Linskey wrote:
First of all, thank you very much for your help. I'm the guy you met in
Bologna few days ago (the one who speaks really bad english). ;-)
Now it works, but there is a step further.
If a transactional field is modifyed inside a transaction, the state of
the object is dirty.
If a persistent field of a detached object is modifyed, when the object is
attached its state is dirty.
If a transactional field of a detached object is modifyed, when the
object is attached its state is NOT dirty.
This is a sample code;
KodoPersistenceManager kpm =(KodoPersistenceManager)pm;
kpm.currentTransaction().begin();
Extent ext = pm.getExtent(Indirizzo.class,true);
Iterator it = ext.iterator();
Indirizzo ind =null,attachedInd,detachInd;
if(it.hasNext()){
ind = (Indirizzo)it.next();
//this is a transactional field
ind.setTransazValue("Pippo");
if(JDOHelper.isDirty(ind)){
System.out.println("STEP 1: DIRTY");
detachInd = (Indirizzo)kpm.detach(ind);
pm.currentTransaction().commit();
//this is a transactional field
detachInd.setTransazValue("Pluto");
pm.currentTransaction().begin();
attachedInd = (Indirizzo)kpm.attach(detachInd);
if(JDOHelper.isDirty(attachedInd)){
System.out.println("STEP 2: DIRTY");
} else {
System.out.println("STEP 2: CLEAN");
detachInd = (Indirizzo)kpm.detach(attachedInd);
kpm.currentTransaction().commit();
// this is a persistent field
detachInd.setDes("foo");
kpm.currentTransaction().begin();
attachedInd = (Indirizzo)kpm.attach(detachInd);
if(JDOHelper.isDirty(attachedInd)){
System.out.println("STEP 3: DIRTY");
} else {
System.out.println("STEP 3: CLEAN");
kpm.currentTransaction().commit();
This is the result of the code above:
STEP 1: DIRTY
STEP 2: CLEAN
STEP 3: DIRTY
This means that Kodo in able to detect changes for a persistent field of a
detached object, but NOT for a transactional field. Is it right?
What happens if you explicitly mark that the field is not mapped? You
can do this by putting the following in your mapping file:
<field name="transazValue">
<jdbc-field-map type="none"/>
</field>
-Patrick
Claudio Tasso wrote:
Hi,
I'd like to define a field of a persistent class as "transactional". This
field is not mapped to a table column, but it must be rolled-back when
transaction aborts.
According to JDO specification, I tryed to use the "persistence-modifier"
attribute of the "field" element in jdo metadata, as follows:
<jdo>
<package name="it.tasso.model">
<class name="Indirizzo" objectid-class="IndirizzoId">
<field name="id" primary-key="true"/>
<field name="transazValue" persistence-modifier="transactional"/>
</class>
</package>
</jdo>
But at runtime, when the persistent object is retrieved from the
datastore, the following error occurs:
Exception in thread "main" kodo.jdbc.meta.MappingInfoNotFoundException: No
mapping information was found for "it.tasso.model.Indirizzo.transazValue".
I't obvious that there's no mapping information, because that field is
just transactional. In fact, kodo documentation says:
persistence-modifier: Specifies how JDO should manage the field. Legal
values are persistent for persistent fields, transactional for fields that
are non-persistent but can be rolled back along with the current
transaction,
If the persistence-modifier attribute is set to NONE, no errors occurs.
Where's my mistake?