Hallo,
I'm new to gae and I'm a bit confused with the way the datastore is
handling transactions. I believe that all in all I have figured out
how it works but unfortunatly I receive Exceptions. So this is the
problem: Three Class AbtractAdd DetailedAdd and AddConcept have to be
in the same Entitygroup for they are changed in one transaction. Here
is some code that i believe is most important:
public class AbstractAdd implements Serializable{
private static final long serialVersionUID = 1061921369184491066L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Extension(vendorName = "datanucleus",
key = "gae.encoded-pk", value = "true")
private String keyString;
.....
}
public class DetailedAdd implements Serializable{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Extension(vendorName = "datanucleus",
key = "gae.encoded-pk", value = "true")
private String keyString;
@Basic
@Extension(vendorName="datanucleus", key="gae.parent-pk",
value="true")
private String abstractAddKey;
....
}
public class ConceptData implements Serializable{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Extension(vendorName = "datanucleus",
key = "gae.encoded-pk", value = "true")
private String keyString;
@Basic
@Extension(vendorName="datanucleus", key="gae.parent-pk",
value="true")
private String abstractAddKey;
...
}
first I save a abstractAdd object (em.persist(a)) then I assign the
key of the abstract addObject to the abstractAddKey fields of the
other two class. I believed that this way I establishet the entity
group so that I can save the detailedAdd Object and the ConceptData
object in one transaction. But this raises an exception that I can
only modify objects that belong to the same entity group. Please help
me out.
AbstractAdd abstractAdd = request.getAbstractAdd();
DetailedAdd detailedAdd = request.getDetailedAdd();
ConceptData conceptData = request.getConceptData();
em.persist(abstractAdd);
detailedAdd.setAbstractAddKey(abstractAdd.getKeyString());
conceptData.setAbstractAddKey(abstractAdd.getKeyString());
em.persist(detailedAdd);
em.persist(conceptData);
....
}
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