Hi, group!!!
Sometimes my GAE application can't persist collection of child
elements.
I have following objects structure.
@PersistenceCapable(table = "persons", identityType =
IdentityType.APPLICATION)
public class PersonEntity {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Long id;
@Persistent
private String name;
@Persistent
private List<OfferEntity> offers = new ArrayList<OfferEntity>();
// ... getter and setter
}
@PersistenceCapable(table = "offers", identityType =
IdentityType.APPLICATION)
public class OfferEntity {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key id;
@Persistent
private List<ChoosedElementEntity> choosedElements = new
ArrayList<ChoosedElementEntity>();
// ... getter and setter
}
@PersistenceCapable(table = "offer_selections_ce", identityType =
IdentityType.APPLICATION)
public class ChoosedElementEntity {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private com.google.appengine.api.datastore.Key id;
@Persistent
private String filed;
// ... getter and setter
}
First of all I try to persist object of class PersonEntity. It is all
right.
PersistenceManager = null;
try {
pm = getPersistenceManager();
PersonEntity person = new PersonEntity();
// set person fields
pm.makePersistent(person);
} catch (Throwable th) {
} finally {
if (null != pm) {
pm.close();
}
}
Then, I try to add some child elements to OfferEntity. And I am
thoroughly confused: Sometimes child object persists and sometimes
not. This behavior is very strange.
String offerId = ...;
PersistenceManager pm = null;
try {
pm = getPersistenceManager();
OfferEntity dbOffer = pm.getObjectById(OfferEntity.class,
KeyFactory.stringToKey(offerId));
if (null != dbOffer) {
ChoosedElementEntity element = new ChoosedElementEntity();
// set element fields
dbOffer.getChoosedElements().add(element);
log.log(Level.INFO, "try to commit 'added choosed elements':
offerId=" + dbOffer.getId() + ", size: " +
dbOffer.getChoosedElements().size() + ", elements: " +
dbOffer.getChoosedElements());
pm.makePersistent(dbOffer);
}
} catch (Throwable th) {
log.log(Level.SEVERE, "Can't add choosed elements to offer entity:
offerId=" + offerId, th);
throw new ServiceException("Can't add choosed elements to offer
entity: offerId=" + offerId, th);
} finally {
if (null != pm) {
pm.close();
}
}
I try to analyze some child information before persist parent object
and I note, that from time to time child element has/hasn't value for
primary key.
Example:
"try to commit 'added choosed elements': offerId=persons(1092001)/
offers(1), size: 1, elements:
[ChoosedElementEntity{id=persons(1092001)/offers(1)/
offer_selections_ce(5001), filed='filed765'}]"
or
"try to commit 'added choosed elements': offerId=persons(1092001)/
offers(1), size: 1, elements: [ChoosedElementEntity{id=null,
filed='filed766'}]"
Any help would be greatly appreciated. Thanks.
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