Hi,
I'm sure the question was asked several times but I didn't find any valuable
hints in the mailing list. I just want to delete a object and
all the sub-objects as defined in repository.xml. That all with locking of
the root object and in one transaction.
I have the class definition in repository.xml as follows:
<class-descriptor>
...
<collection-descriptor
name="subActions"
element-class-ref="de.virtualsolution.ojb.Action"
collection-class="org.apache.ojb.odmg.collections.DListImpl"
>
<inverse-foreignkey field-id-ref="3"/>
</collection-descriptor>
</class-descriptor>
there are some fields and one collection holding sub-actions. The
sub-actions can also have sub-actions. That's a tree structure. I have the
collection class defined because I though only that one is aware of removing
all the childs, doesn't it ? Ok to delete the action I perform a query like
this
Action action = new Action();
action.setId(id);
// 2. build a QueryByExample from this sample instance:
Query query = new QueryByExample(action);
// 4. lookup the product specified by the QBE
action = (Action) broker.getObjectByQuery(query);
and wanna delete the action with deleteObject(action) ....
------------------------------
static public void deleteObject(Object obj) throws DBException {
String databaseName = null;
if (obj == null) {
return;
}
try {
databaseName =
((PersistenceBrokerConfiguration) PersistenceBrokerFactory
.getConfigurator()
.getConfigurationFor(null))
.getRepositoryFilename();
}
catch (ConfigurationException e) {
databaseName = "repository.xml";
}
// get facade instance
Implementation odmg = OJB.getInstance();
Database db = odmg.newDatabase();
//open database
try {
db.open(databaseName, Database.OPEN_READ_WRITE);
}
catch (ODMGException ex) {
m_log.error("Error while opening ODMG database", ex);
throw new DBException("Error while opening ODMG database", ex);
}
Transaction tx = odmg.newTransaction();
//perform transaction
try {
tx.begin();
tx.lock(obj, Transaction.WRITE);
db.deletePersistent(obj);
tx.commit();
}
catch (Exception ex) {
tx.abort();
} finally {
try {
db.close();
} catch (ODMGException ex) {
m_log.error("Error while closing ODMG database", ex);
throw new DBException("Error while closing ODMG database",
ex);
}
} //end finally
}
-------------------------------
Only the root object was deleted. My question is what are the settings for
cascade deleting ? What is the drawback if i go to use the PB API and
auto-delete setting in the descriptor ?
What really means the object locking ? It doesn't prevent another client
from setting new values while the object is locked, so what's going on ?
Thanx for any help.
Thomas
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