unable to set fields of a collection-property elements after changing their order (elements becoming
- by Jaroslav Záruba
Hello
I want to change order of objects in a collection, and then to access+modify fields of those items. Unfortunately the items somehow become 'deleted'.
This is what I do...
if(someCondition)
{
MainEvent mainEvent = pm.getObjectById(MainEvent.class, mainEventKey);
/*
* events in the original order
* MainEvent.subEvents field is not in default fetch group,
* therefore I also tried to add the named group into the
* persistenceManeger fetch plan, no difference
* (mainEvent is not instance of the Event sub/class BTW)
*/
List<Event> subEvents = mainEvent.getSubEvents();
// re-arrange the events according to keysOrdered {
Map<Key, Event> eventMap = new HashMap<Key, Event>();
for(Event event : subEvents)
eventMap.put(event.getKey(), event);
List<Event> eventsOrdered = new LinkedList<Event>();
for(Key eventKey : keysOrdered)
eventsOrdered.add(eventMap.put(eventKey, eventMap.get(eventKey)));
// }
// put the re-arranged items back into the collection property {
subEvents.clear();
subEvents.addAll(eventsOrdered);
// }
pm.makePersistent(mainEvent);
eventsOrdered = subEvents;
}
else
eventsOrdered = getEventsUsingAlternateApproach();
/*
* so by now the mainEvent variable does not exist;
* could it be this lead the persistence manager to mark
* my events as abandoned/obsolete/invalid/deleted...?
*/
for(Event event : eventsOrdered)
event.setDate(new Date()); // -> "Cannot write fields to a deleted object"
What am I doing wrong please?
