Schema-Update: Rename superclass and remove one subclass

Hello,

we renamed a superclass and removed one of the subclass.

If we then try to open the Database (with ObjectDB-Explorer) we get a "Failed to generate dynamic type ..."

Small Example:

Generate Database

public static void main(String[] args) {
  EntityManagerFactory emf = Persistence.createEntityManagerFactory("objectdb:test.tmp;drop");
  EntityManager em = emf.createEntityManager();

  // // Persist an entity
  em.getTransaction().begin();
  ChildClassA entity1 = new ChildClassA();
  entity1.kind = "kindA";
  entity1.mode = "modeB";
  em.persist(entity1);
  ChildClassA entity2 = new ChildClassA();
  entity2.kind = "kindC";
  entity2.mode = "modeD";
  em.persist(entity2);
  ChildClassB entity3 = new ChildClassB();
  entity3.onlyRecordLastStep = false;
  em.persist(entity3);
  em.getTransaction().commit();

  em.close();
  emf.close();
}

Entities:

@Entity
@Access(AccessType.FIELD)
public class SuperClass {

  public SuperClass() {
  }
}

ChildClassA:

@Entity
@Access(AccessType.FIELD)
public class ChildClassA extends SuperClass {

@Basic public String kind;

@Basic public String mode;

  protected ChildClassA() {
  }
}

ChildClassB:

@Entity
@Access(AccessType.FIELD)
public class ChildClassB extends SuperClass {

@Basic
public boolean onlyRecordLastStep = false;

  protected ChildClassB() {
  }
}

Then we rename SuperClass to RenamedSuperClass and Remove the ChildClassB.

<schema>
    <package name="schemaupdate.delete">
         <class name="SuperClass" new-name="RenamedSuperClass" />
    </package>
</schema>

@Entity
@Access(AccessType.FIELD)
public class RenamedSuperClass {

  public RenamedSuperClass() {
  }
}

@Entity
@Access(AccessType.FIELD)
public class ChildClassA extends RenamedSuperClass {

@Basic public String kind;

@Basic public String mode;

  protected ChildClassA() {
  }
}

And then we access the prevous create Database with the following example:

public static void main(String[] args) {

  // no drop - reuse the existing file
  EntityManagerFactory emf = Persistence.createEntityManagerFactory("objectdb:test.tmp");
  EntityManager em = emf.createEntityManager();

  // don't create a new objects!
  // access the existing

  emf.getMetamodel().entity(RenamedSuperClass.class);

  em.getTransaction().begin();
  // do something
  ChildClassA entityWithID1 = em.find(ChildClassA.class, 1);
  entityWithID1.mode = "a";
  ChildClassA entityWithID2 = em.find(ChildClassA.class, 2);
  entityWithID2.mode = "b";
  em.getTransaction().commit();

  em.close();
  emf.close();
}

If we try to open the database with the ObjectDB-Explorer we get the described error message.

If we try to ecexute a Query (in the second main method):

TypedQuery<RenamedSuperClass> q = em.createQuery("SELECT c FROM " + RenamedSuperClass.class.getName() + " c",
    RenamedSuperClass.class);
 List<RenamedSuperClass> result = q.getResultList();
 System.out.println("size: " + result.size());

We get an exception:

[2016-11-14 10:48:56 #1 *]
java.lang.NullPointerException
at com.objectdb.o.ENH.g(ENH.java:401)
at com.objectdb.o.OBC.aM(OBC.java:951)
at com.objectdb.o.OBC.UZ(OBC.java:798)
at com.objectdb.o.SRB.l(SRB.java:160)
at com.objectdb.o.QRR.m(QRR.java:549)
at com.objectdb.o.QRR.f(QRR.java:212)
at com.objectdb.jpa.JpaQuery.getResultList(JpaQuery.java:719)
at schemaupdate.delete.UpdateDB.main(UpdateDB.java:32)

Exception in thread "main" [ObjectDB 2.6.9_07] Unexpected exception (Error 990)
  Generated by Java HotSpot(TM) 64-Bit Server VM 1.8.0_51 (on Windows 7 6.1).
Please report this error on http://www.objectdb.com/database/issue/new
com.objectdb.o.InternalException: java.lang.NullPointerException: null
java.lang.NullPointerException
at com.objectdb.o.ENH.g(ENH.java:401)
at com.objectdb.o.OBC.aM(OBC.java:951)
at com.objectdb.o.OBC.UZ(OBC.java:798)
at com.objectdb.o.SRB.l(SRB.java:160)
at com.objectdb.o.QRR.m(QRR.java:549)
at com.objectdb.o.QRR.f(QRR.java:212)
at com.objectdb.jpa.JpaQuery.getResultList(JpaQuery.java:719)
at schemaupdate.delete.UpdateDB.main(UpdateDB.java:32)

Thank you for this report and for the test. It demonstrates well a bug in schema evolution that includes renaming a super class and removing one of its subclasses at the same time. This report was moved to the issue tracking for further discussion and tracking.