You can follow something like that
class Parent {
....
@Persistent
private List<Long/Key> childList;
// non Persistent
private List<Child> list;
...
}
class Child {
@PrimaryKey
private Long/Key key;
...
}
// before save Parent
private void beforeSave(EntityManager em,Parent pa) {
if (pa.getList() != null) {
List<Long> chList = new ArrayList<Long>();
for (Child ch : pa.getList) {
pm.makePersistent(ch);
pm.flush();
chList.add(ch.getKey());
}
pa.setChildList(chList);
}
}
private void afterLoad(EntityManager em,Parent pa) {
List<Child> chList = new ArrayList<Child>();
for (Long key : pa.getChildList()) {
Child ch = pm.getObjectById(Child.class,key);
chList.add(ch);
}
pa.setList(chList);
}
PersistenManager pm;
....
// main service
Parent pa = pm..getObjectById(...)
afterLoad(pm,pa);
...
...
beforeSave(pm,pa);
pm.makePersistent(pa);
List<Parent> pList = pm.queryExecute();
for (Parent pa : pList) {
afterLoad(pm,pa);
}
...
// etc
In order to avoid repeating the same beforeSave and afterLoad for all
Entity classes having "onowned" relationship you can apply Annotation
and, by the use of reflection, develop generic approach for all
classes having this feature.
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