Declared metamodel attributes work fine BUT Inherited Metamodel Attributes are NULL. Why?

Question

I am not able to run the following test:-

@Test
public void test() {
    EntityManager em = entityManagerFactory.createEntityManager();
    em.getTransaction().begin();

    CriteriaBuilder builder = em.getCriteriaBuilder();
    CriteriaQuery<Project> query = builder.createQuery(Project.class);

    Root<Project> project = query.from(Project.class);

    Path<String> name = project.get(Project_.name);
    Assert.assertNotNull(name);

    Path<EntityLifeCycleImpl> lifeCycle = project.get(Project_.lifeCycle); // problem is here, throws NullPointer
    Assert.assertNotNull(lifeCycle);
}

it throws NullPointerException at project.get(Project_.lifeCycle) line. Why?

java.lang.NullPointerException
    at org.hibernate.ejb.criteria.path.AbstractPathImpl.get(AbstractPathImpl.java:138)

PersistenceEntityBase.java

import org.hibernate.annotations.GenericGenerator;
        @MappedSuperclass
@Access(AccessType.PROPERTY)
public abstract class PersistentEntityBase {

protected String identifier;

protected EntityLifeCycleImpl lifeCycle = new EntityLifeCycleImpl();

protected PersistentEntityBase() {
}

@Id
@GeneratedValue(generator="generator") 
@GenericGenerator(name="generator", strategy="guid", parameters = {})
@Column(name="identifier")
public String getIdentifier() {
    return identifier;
}

public void setIdentifier(String identifier) {
    this.identifier = identifier;
}

@Embedded
public EntityLifeCycleImpl getLifeCycle() {
    return lifeCycle;
}
public void setLifeCycle(EntityLifeCycleImpl lifeCycle) {
    this.lifeCycle = lifeCycle;
}

}

Project.java

@Entity
@Table(name="project")
@Access(AccessType.PROPERTY)
public class Project extends PersistentEntityBase {

    private String name;

    protected Project() {
    }

    public Project(String name) {
        this();
        this.name = name;
    }

    @Column(name="name", nullable=false, unique=true)
    public String getName() {
        return name;
}
public void setName(String name) {
    this.name = name;
}

}

EntityLifeCycleImpl.java

@Embeddable
public class EntityLifeCycleImpl implements EntityLifeCycle {
    private String createdBy;
    private Date createdDate;
       @Column(name="created_by")
public String getCreatedBy() {
    return createdBy;
}
public void setCreatedBy(String createdBy) {

    this.createdBy = createdBy;
}

@Column(name="created_date")
public Date getCreatedDate() {
    return createdDate;
}
public void setCreatedDate(Date createdDate) {
    this.createdDate = createdDate;
}

}

PersistentEntityBase_.java (Generated using Hibernate Metamodel Generator)

   @StaticMetamodel(PersistentEntityBase.class)
public abstract class PersistentEntityBase_ {
    public static volatile SingularAttribute<PersistentEntityBase, EntityLifeCycleImpl> lifeCycle;
        public static volatile SingularAttribute<PersistentEntityBase, String> identifier;
     }

Project_.java

    @StaticMetamodel(Project.class)
public abstract class Project_ extends PersistentEntityBase_ {
    public static volatile SingularAttribute<Project, String> name;
    }

EntityLifeCycleImpl_.java

   @StaticMetamodel(EntityLifeCycleImpl.class)
public abstract class EntityLifeCycleImpl_ {
    public static volatile SingularAttribute<EntityLifeCycleImpl, String> createdBy;
    public static volatile SingularAttribute<EntityLifeCycleImpl, Date> createdDate;
}

persistence.xml (only relavent part)

<class>com.comp.timetracking.entity.PersistentEntityBase</class>
<class>com.comp.timetracking.entity.Project</class>

EDIT: I use hibernate-entitymanager.3.6.0.Final and hibernate-jpamodelgen.1.0.0.Final.

EDIT 2 @Pascal
I think Hibernate EM 3.6.0.Final allows us to define @Embedded annotated field at @Entity level but it denies such field at @MappedSuperclass level. What do you say?

As I cannot see "file upload option" here, I've uploaded the TestCase in my esnips account. Download the maven-based-project and run SingularAttributeTest.java. And checkout the console output

ERROR main metamodel.MetadataContext:413 - Unable to locate static metamodel field : timetracking.entity.Employee_#lifeCycle

Click on "Download embedded-singular-attribute.zip" link to download the file WITHOUT installing the download manager. (If you click on Download link with Green arrow, you'll have to install the download manager!!)

Answer 1

I tested your classes and test case with EclipseLink (I removed the Hibernate specific parts) and the test passes. But it indeed fails with Hibernate 3.5.6. Looks like a bug in Hibernate.

By the way, you are missing a Temporal annotation in your Embeddable

@Column(name = "created_date")
@Temporal(TemporalType.DATE)
public Date getCreatedDate() {
    return createdDate;
}

And you are not supposed to declare PersistentEntityBase in the persistence.xml (a mapped super class is not an entity).

Answer 2

this is not an issue.

From Hibernate documentation:

If class X extends another class S, where S is the most derived managed class (i.e., entity or mapped superclass) extended by X, then class X_ must extend class S_, where S_ is the metamodel class created for S.

https://docs.jboss.org/hibernate/entitymanager/3.5/reference/en/html/metamodel.html

Answer 3

I had the same problem: During deployment the jboss 7.0.2 reported the following error: "Unable to locate static metamodel field X" where X is a field inherited from a @MappedSuperclass and annotated with @Embedded (the type of X is a class annotated with @Embeddable).

I solved it adding the classes annotated with @Embeddable and @MappedSuperclass, together with the classes annotated with @Entity, in the list of classes to be managed by the persistence unit. This is configured in the "persistence.xml" file.