Question

I have a weird error of double insert in the DB. I have the following classes:

• TestEntity – entity with a @PrePersist and a @PostPersist methods.
• Auditoria – audit entity
• Dataset – interface of DatasetBean
• DatasetBean – Stateless bean which implements Dataset
• DatasetFactory – instance an EJB of Dataset (lookup)

I put the problem in a junit test (I’m using embedded Glassfish):

@Test
public void test() throws NamingException {
    Dataset<TestEntity> dataset = this.lookupBy(DatasetBean.class);
    Assert.assertNotNull(dataset);

    TestEntity t = new TestEntity();        
    t.setName(UUID.randomUUID().toString());

    dataset.insert(t);
    System.out.println("end");
}

The flow of the test is the following:

1. After gettin a Dataset object, I try to insert a TestEntity object

   @Stateless
   @EJB(name = “…”, beanInterface = Dataset.class)
   public class DatasetBean implements Dataset {

   @PersistenceContext(type = PersistenceContextType.TRANSACTION)
   private EntityManager entityManager;
   
   @Override
   public void insert(T entidade) {
       LOG.info("Inserting: " + entidade);
       entityManager.persist(entidade);
   }
   //...
   

   }

2. Using the DatasetFactory, I try to insert an Auditing entity in a @PostPersist method of the TestEntity

   public class DatasetFactory {
   public static Dataset createDataset() {
   try {
   return (Dataset) new InitialContext().lookup(“…”);
   } catch (Exception ex) {
   throw new RuntimeException(ex);
   }
   }
   }

   @Entity
   public class TestEntity implements MyEntity {
   @Id
   private Integer id;
   private String name;
   // sets and gets

   @PrePersist
   public void fillId() {
       if (getId() == null || getId() == 0) {
           Dataset d = DatasetFactory.createDataset();
           Integer i = (Integer) d.fetchJPQLFirstResult("SELECT MAX(te.id) FROM TestEntity te");
           if (i == null || i < 100) {
               setId(100);
           } else {
               setId(i + 1);
           }
       }
   }  
   
   @PostPersist
   public void audit() {
       Dataset<Auditing> dataset = DatasetFactory.createDataset();
       // dataset.getEntityManager().clear();
       Auditing auditing = new Auditing();
       auditing.setIdEntidade(String.valueOf(this.getId()));
       dataset.insert(auditing);
   }
   

   }

   @Entity
   public class Auditoria implements MyEntity {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   private Integer id;
   private String idEntity;
   //sets and gets
   }

   public interface MyEntity extends Serializable {
   Integer getId();
   }

Log:

INFO: embedded was successfully deployed in 47.154 milliseconds.
PlainTextActionReporterSUCCESSDescription: deploy AdminCommandApplication deployed with name embedded.

2012-01-06 02:56:54,826 [main] INFO com.joaosavio.model.db.DatasetBean (DatasetBean.java:30) – Inserting: TestEntity{id=null, name=ea5c2af4-0ca7-48a2-a82a-dbf582c570a9}

Hibernate: select max(testentity0_.id) as col_0_0_ from TestEntity testentity0_

Hibernate: insert into TestEntity (name, id) values (?, ?)

2012-01-06 02:56:56,344 [main] INFO com.joaosavio.model.db.DatasetBean (DatasetBean.java:30) – Inserting: Auditoria{id=null, idEntidade=100}

Hibernate: insert into TestEntity (name, id) values (?, ?)

2012-01-06 02:56:56,350 [main] WARN org.hibernate.engine.jdbc.spi.SqlExceptionHelper (SqlExceptionHelper.java:143) – SQL Error: 2627, SQLState: 23000

2012-01-06 02:56:56,352 [main] ERROR org.hibernate.engine.jdbc.spi.SqlExceptionHelper (SqlExceptionHelper.java:144) – Violation of PRIMARY KEY constraint ‘PK_TestEntity_76818E95′. Cannot insert duplicate key in object ‘dbo.TestEntity’.

06/01/2012 02:56:56 com.sun.ejb.containers.BaseContainer postInvoke

WARN: A system exception occurred during an invocation on EJB DatasetBean method public void com.joaosavio.model.db.DatasetBean.insert(java.lang.Object)
javax.ejb.TransactionRolledbackLocalException: Exception thrown from bean
…

Caused by: javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: Violation of PRIMARY KEY constraint ‘PK_TestEntity_76818E95′. Cannot insert duplicate key in object ‘dbo.TestEntity’.
…

Caused by: org.hibernate.exception.ConstraintViolationException: Violation of PRIMARY KEY constraint ‘PK_TestEntity_76818E95′. Cannot insert duplicate key in object ‘dbo.TestEntity’.

Considerations:

Relying on the fact that everything works fine if I clear the entity manager before the insertion of the Auditing entity (comented code in @PostPersist method in TestEntity), I believe that the TestEntity is getting stuck in the transaction.

What am I doing wrong???

Answer 1

Ive seen a very similar issue once…. You should —

Be very careful with @PostPersist ! hibernate bean persist or save actions ARE NOT the same as database Insertions!

The problem is likely that are that you are assuming that @PostPersist methods are invoked after the data has been inserted …. However , that is not always the case! PostPersist methods are callbacks BUT they are not callbacks from the database !!! As you know – hibernate may not have committed your transaction And flushed it completely. if you try to use PostPersist to coordinate barriers between your database transactions, you are making a mistake.

The solution is to do all your inserts in a single properly planned and managed transaction, with keys and cascades worked out so that hibernate will be able to organize the inserts for you in the right way— or just hardcode a stored procedure to do the work for you.

I think you might be merging stateful and stateless transaction logic here.