Updating Transient objects in Kodo 2.5.5

Question

I have a situation where I construct a JDO object in transient state in my
code ( for batch processing of data from a file into the database) by
calling the objects contructor and setting it's values. The row
representing this object may or may not exist in the database.
How do I make the object peristant ? If the row already exists, then I
must be able to update the row with the new values ( non-primary keys ).
If not, I should insert a new row.
There are no multi table relationships involved in this case. A JDO object
represents just one table.
We want to avoid the scheme which involves retrieve the object first and
then trying to update in a transaction.
Adarsh

Answer 1

Transaction t = kpm.currentTransaction();
try {
MyObject o = new MyObject(...)
t.begin();
Object id = ((PersistenceCapable)o).jdoNewObjectIdInstance();
((PersistenceCapable)o).jdoCopyKeyFieldsToObjectId(id);
try{
System.out.println(id);
Object trio = pm.getObjectById(id,true);
pm.deletePersistent(trio);
}catch(ObjectNotFoundException oe){
System.out.println("First time!");
pm.makePersistent(o);
t.commit();
}catch(...){