Incompete entity returned for getSingleResult when using Joined Inheritance
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Key: OPENJPA-1883
URL: https://issues.apache.org/jira/browse/OPENJPA-1883
Project: OpenJPA
Issue Type: Bug
Affects Versions: 2.0.1
Environment: Mac OS X 10.6 Server, Spring Framework 3.0.5, OpenJPA
2.0.1
Reporter: Jerry Carter
I have a child class 'B' which extends via Joined Inheritance the class 'A'.
The entityManager.getSingleResult function returns an incomplete instantiation
of the entity if not already in cache. I can't speak for the JPA 2.0
specification, but the behavior of OpenJPA is clearly inconsistent and this
looks like a clear bug. A more complete description of the problem appears
below.
FWIW, this surprised me in production after having passed all my unit tests.
The unit tests assumed an empty database and therefore created the entities
before persisting them. This caused the entities to be placed in cache.
Subsequent attempts to load each entity then returned the full object. In
production, however, the cache starts off empty and the 'getSingleResult' call
only loads part of the entity. Using an 'em.find' as a workaround then causes
the complete entity to be loaded into the cache. Any subsequent calls to
'getSingleResult' will then return the entire entity.
[A.java]
@Entity
@Inheritance(strategy=InheritanceType.JOINED)
@DiscriminatorColumn(name="class_type",
discriminatorType=DiscriminatorType.INTEGER)
public abstract class A {
// Defines an ID and at least one persistent field.
}
[B.java]
@Entity
@DiscriminatorValue("2")
class B extends A implements Serializable {
...
private String details;
public String getDetails() { return details; }
public void setDetails(String details) { this.details = details; }
...
}
[SomeDAOImpl.java]
TypedQuery<A> query = em.createNamedQuery("GetDetails", A.class);
A a = query.getSingleResult();
Assert.assertTrue(a instanceof B);
Assert.assertNull(a.getDetails()); // ERROR: This should be defined
em.refresh(a);
Assert.assertTrue(a instanceof B);
Assert.assertNull(a.getDetails()); // ERROR: This should be defined
a = em.merge(a);
Assert.assertTrue(a instanceof B);
Assert.assertNull(a.getDetails()); // ERROR: This should be defined
a = em.find(A.class, a.getId());
Assert.assertTrue(a instanceof B);
Assert.assertNotNull(a.getDetails()); // SUCCESS!
a = query.getSingleResult();
Assert.assertTrue(a instanceof B);
Assert.assertNotNull(a.getDetails()); // SUCCESS!
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