persistence

Let's say I have the following scenario: @Entity public class Person { @Id private Long id; //Surrogate key @Embedded private Name name; //Natural key public int hashCode() { ... //based on natural key Name } public boolean equals(Object obj) { ... //based on natural key Name } } @Embeddable public class Name { private String firstName; private String middleName; private String lastName; //Should I implement equals/hashCode baseed on the three fields? } Should Name class implement equals and hashCode on Name class in order that Person equals work properly?. For an Embeddable object that will

My persistence.xml has 2 persistence-units. Each of them has several <class> elements. I thought that we must specify all classes related to certain persistence-unit. But I accidentally forgot to specify class-element for new entity but the program worked fine even without it. Then I removed all class-elements and everything worked fine. So, why do we need it? sample code: <persistence-unit name="JiraManager" transaction-type="RESOURCE_LOCAL"> <class>chartdemo.model.domain.Category</class> </persistence-unit> If you didn't specify classes in the persistence.xml file your persistence manager

I'm using 2 PU in stateless EJB and each of them is invoked on one method: @PersistenceContext(unitName="PU") private EntityManager em; @PersistenceContext(unitName="PU2") private EntityManager em2; @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW ) public void getCandidates(final Integer eventId) throws ControllerException { ElectionEvent electionEvent = em.find(ElectionEvent.class, eventId); ... Person person = getPerson(candidate.getLogin()); ... } @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW ) private Person getPerson(String login) throws ControllerException {

I am working on a JPA project. I need to use a @OneToMany mapping on a class that has three primary keys. You can find the errors and the classes after this. javax.persistence.PersistenceException: No Persistence provider for EntityManager named JTA_pacePersistence: Provider named oracle.toplink.essentials.PersistenceProvider threw unexpected exception at create EntityManagerFactory: javax.persistence.PersistenceException javax.persistence.PersistenceException: Exception [TOPLINK-28018] (Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): oracle.toplink.essentials.exceptions

I'm researching the development of Enterprise Applications in Java, .NET and Groovy. For each platform, we're going to try how hard it is to realize a simple SOAP web service. We'll use the tools and libraries that are most commonly used, to research the real world as accurately as possible. In this regard, when using Hibernate for persistence, would it better reflect the real world to use the new JPA (Java Persistence API), or the Hibernate custom API that existed before JPA came around? As you're probably already aware, as of 3.2 Hibernate is JPA certified. You can easily use Hibernate as

I'm setting up a basic test data util and want to keep track of all the data that the EntityManager handles. Rather than just having a bunch of lists for each entity is there a way to grab everything being managed by the EntityManager in one fell swoop? So instead of this: EntityManager em; List<Entity1> a; List<Entity2> b; ... List<Entityn> n; cleanup() { for(Entity1 e : a) em.remove(e); for(Entity2 f : b) em.remove(f); ... for(Entityn z : n) em.remove(z); } I want something like this; EntityManager em; cleanup() { List<Object> allEntities = em.getAllManagedEntities(); //<-this doesnt exist

I'm working on a project on an unreliable system which I'm assuming can fail at any point. What I want to guarantee is that if I write_state and the machine fails mid-operation, a read_state will either read a valid state or no state at all. I've implemented something which I think will work below -- I'm interested in criticism of that or alternative solutions if anyone knows of one. My idea: import hashlib, cPickle, os def write_state(logname, state): state_string = cPickle.dumps(state, cPickle.HIGHEST_PROTOCOL) state_string += hashlib.sha224(state_string).hexdigest() handle = open('%s.1' %