Question

I have some problems with my DAO implementation. My scenario: I insert one entity in my database, I get this entity twice from my database. I understand difference between AssertSame and AssertEquals. I guess that the same entity should pass in both cases. In my case AssertEquals passes ,but AssertSame fails.

I have been struggling with that for a long time and any help will be greatly appreciated.

My question is: What conditions have to be met in order to be sure that these two entities are the same? What should I change in my code?

I pasted only parts of my classes and config files which I in my opinion are essential.

StudentEntity class is annotated with @Entity.

I’v prepared the following jUnit test:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "/dao-context.xml", "/hibernate-context.xml", "/core-context.xml" })
public class BidirectionalTest {

    @Autowired
    private UserService userService;

    @Test
    public void testBidirectionalRelation() {
        try {
            StudentEntity s = new StudentEntity();
            s.setLogin("Login");
            userService.registerUser(s);
            StudentEntity foundStudent1 = (StudentEntity) userService.findUserByLogin("Login");
            StudentEntity foundStudent2 = (StudentEntity) userService.findUserByLogin("Login");
            assertEquals(foundStudent1, foundStudent2);
            assertSame(foundStudent1, foundStudent2); // fail!
        } catch (ServiceException e) {
            e.printStackTrace();
        }
    }
}

Part of my service implementation:

@Transactional(propagation=Propagation.REQUIRED)
public class UserServiceImpl implements UserService{

private UserDao userDao;

public AbstractUserEntity findUserByLogin(String login) throws ServiceException {
    Long userId = getUserDao().findUserByLogin(login);
    if(userId == null) {
        return null;
    }
    return getUserDao().findUser(userId);
}

public Long registerUser(AbstractUserEntity user) throws ServiceException {
    Long duplicateUserId = getUserDao().findUserByLogin(user.getLogin());
    if (duplicateUserId!=null) {
        throw new ServiceException("Użytkownik już istnieje");
    }
    return getUserDao().insertUser(user);
}
}

Part of my dao implementation:

@Repository
public class HibernateUserDao implements UserDao {

private EntityManagerFactory emf;

public EntityManagerFactory getEmf() {
    return emf;
}

@PersistenceUnit
public void setEmf(EntityManagerFactory emf) {
    this.emf = emf;
}

@Override
public Long insertUser(AbstractUserEntity user) {
    EntityManager em = emf.createEntityManager();
    try {
        em.getTransaction().begin();
        em.persist(user);
        em.getTransaction().commit();
    } finally {
        if (em != null) em.close();
    }
    return user.getId();
}

@Override
public Long findUserByLogin(String login) {
    EntityManager em = emf.createEntityManager();
    Long result;
    try{
        result = (Long) em.createNamedQuery("findUserByLogin").setParameter("login", login).getSingleResult();          
    } catch(NoResultException nre) {
        return null;
    }
    return result;
}

}

Part of my persistence.xml

<persistence-unit name="JpaPersistenceUnit" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <properties>
        <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" />
        <property name="hibernate.dialect" value="org.hibernate.dialect.DerbyDialect" />
        <property name="hibernate.hbm2ddl.auto" value="create-drop" />
        <property name="show_sql" value="true" />
    </properties>
</persistence-unit>

Part of my core-context.xml

<!-- enable the configuration of transactional behavior based on annotations -->
<tx:annotation-driven transaction-manager="transactionManager" />

<!-- a PlatformTransactionManager is still required -->
<bean id="transactionManager" class="org.springframework.transaction.jta.JtaTransactionManager">
    <property name="transactionManager">
        <ref local="atomikosTM" />
    </property>
    <property name="userTransaction">
        <ref local="atomikosUTX" />
    </property>
</bean>

<bean id="atomikosTM" class="com.atomikos.icatch.jta.UserTransactionManager" />
<bean id="atomikosUTX" class="com.atomikos.icatch.jta.UserTransactionImp" />

edit:

Thx for your answers. Now I know I need a cache. I found a good explanation: “In JPA object identity is not maintained across EntityManagers. Each EntityManager maintains its own persistence context, and its own transactional state of its objects.” I changed my persistence.xml, but my test still fails.

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
         version="2.0">
<persistence-unit name="JpaPersistenceUnit" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <class>amg.training.spring.model.StudentEntity</class>
    <class>amg.training.spring.model.SubjectEntity</class>
    <class>amg.training.spring.model.TeacherEntity</class>
    <class>amg.training.spring.model.AbstractUserEntity</class>
    <class>amg.training.spring.model.TeacherDegree</class>
    <class>amg.training.spring.dao.AbstractEntity</class>
    <shared-cache-mode>ALL</shared-cache-mode>
    <properties>
        <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" />
        <property name="hibernate.dialect" value="org.hibernate.dialect.DerbyDialect" />
        <property name="hibernate.hbm2ddl.auto" value="create-drop" />
        <property name="show_sql" value="true" />
        <property name="hibernate.cache.provider_class" value="org.hibernate.cache.EhCacheProvider"/>
        <property name="hibernate.cache.use_second_level_cache" value="true"/>
        <property name="hibernate.cache.use_query_cache" value="true"/>
    </properties>
</persistence-unit>

Answer 1

Finally managed to make it work. I think that lack of cache was not a problem. It is necessary to bind a resource (in our case EntityManagerFactory ) to the same thread. link to doc of .bindResource() method

@PersistenceUnit
private EntityManagerFactory emf;
private EntityManager em;

@Before
public void setUp() {
    em = emf.createEntityManager();
    TransactionSynchronizationManager.bindResource(emf, new EntityManagerHolder(em));
}

@After
public void tearDown() {
TransactionSynchronizationManager.unbindResource(emf);
EntityManagerFactoryUtils.closeEntityManager(em);
}