@Transactional in @Entity doesn't work?

Question

Going further into Hibernate i've stumbled upon the following situation: I have an @Entity Person

@Entity
@Table(name = "PERSON")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="type",discriminatorType=DiscriminatorType.STRING)
@DiscriminatorValue(value="person")
public class Person implements PersonInterface{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "USER_ID")
    protected Integer id;

    @Column(name = "NAME")
    protected String name;

    @ElementCollection
    @Formula("(SELECT groupId FROM PERSON_GROUPS WHERE id = id")
    protected List<Integer> groups = new ArrayList<>();

    @Override
    public Integer getId() {
        return id;
    }

    @Override
    public Collection<Integer> getGroups(){
        return groups;
    }

    @Override
    public String getName() {
        return name;
    }
}

Which is split in two parts, Immutable and Mutable:

@Entity
@DiscriminatorValue("mutableperson")
@Transactional
public class MutablePerson extends Person implements MutablePersonInterface{

    @Override
    public void setName(String name) {
        this.name = name;
    }

    @Override
    public void setId(Integer id) {
        this.id = id;
    }

    @Override
    public void setGroups(List<Integer> groupIds) {
        this.groups = groupIds;
    }

    public void excludeFromGroup(Integer groupId){
        Hibernate.initialize(this.groups);
        this.groups.remove(groupId);
    }
}

Now, when i try to call something like:

Session session = sessionFactory.openSession();
MutablePerson personFromDb = (MutablePerson) personService.getMutablePersonById(0);
personFromDb.excludeFromGroup(group1.getId());
session.saveOrUpdate(personFromDb);

I get an exception:

Exception in thread "main" org.hibernate.HibernateException: collection is not associated with any session
at org.hibernate.collection.internal.AbstractPersistentCollection.forceInitialization(AbstractPersistentCollection.java:704)
at org.hibernate.Hibernate.initialize(Hibernate.java:65)
at com.studytrails.tutorials.springhibernatejpa.MutablePerson.excludeFromGroup(MutablePerson.java:57)
at com.studytrails.tutorials.springhibernatejpa.TestSpringHibernateJpa.main(TestSpringHibernateJpa.java:48)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

Which tells me, that @Transactional annotation for that MutablePerson class doesn't really work and Hibernate is not creating a transaction.

Here's this bit of my spring configuration:

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory" />
    <property name="dataSource" ref="dataSource" />
    <property name="jpaDialect" ref="jpaDialect" />
</bean>

<tx:annotation-driven transaction-manager="transactionManager" />

As far as i can tell from Hibernate docs and examples, this config is correct and it should work, but it doesn't. Am i missing yet another Hibernate nuance here?

P.S. I know i could've done this in DAO or Service class, but unfortunately i'm bound to use existing API, which works with groups in the mutable half of the entity.

Answer 1

Entities are not managed by Spring. they are created as a product of database operation via hibernate or manually to save date. therefore the @Transactional annotation will not work as this is not a spring managed bean.

Spring transactional context wraps around a spring managed bean and act on it. it cannot wrap non spring beans

Possible Solution Move the transactional context ideally for service layer or at least Jpa Repository/Dao layer.