Hibernate: "Field 'id' doesn't have a default value"

Question

Hi, all. I'm facing what I think is a simple problem with Hibernate, but can't get over it (Hibernate forums being unreachable certainly doesn't help).

I have a simple class I'd like to persist, but keep getting:

SEVERE: Field 'id' doesn't have a default value
Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not insert: [hibtest.model.Mensagem]
    at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:103)
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:91)
    [ a bunch more ]
Caused by: java.sql.SQLException: Field 'id' doesn't have a default value
    [ a bunch more ]

The relevant code for the persisted class is:

package hibtest.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public class Mensagem  {
    protected Long id;

    protected Mensagem() { }

    @Id
    @GeneratedValue
    public Long getId() {
        return id;
}

    public Mensagem setId(Long id) {
        this.id = id;
        return this;
    }
}

And the actual running code is just plain:

SessionFactory factory = new AnnotationConfiguration()
    .configure()
    .buildSessionFactory();

{
    Session session = factory.openSession();
    Transaction tx = session.beginTransaction();

    Mensagem msg = new Mensagem("YARR!");

    session.save(msg);

    tx.commit();
    session.close();
}

I tried some "strategies" within the GeneratedValue annotation but it just doesn't seem to work. Initializing id doesn't help either! (eg Long id = 20L).

Could anyone shed some light?

EDIT 2: confirmed: messing with@GeneratedValue(strategy = GenerationType.XXX) doesn't solve it

SOLVED: recreating the database solved the problem

Answer 1

TopLink JPA has some insight:

http://www.oracle.com/technology/products/ias/toplink/jpa/howto/id-generation.html

Even if you're not using TopLink, it suggests that you have to tell JPA what your generation scheme is going to be. I use identity for MS SQL and MySQL and sequences for Oracle and PostgreSQL. What are you using?

Answer 2

Take a look at GeneratedValue's strategy. It typically looks something like:

@GeneratedValue(strategy=GenerationType.IDENTITY)

Answer 3

Sometimes changes made to the model or to the ORM may not reflect accurately on the database even after an execution of SchemaUpdate.

If the error actually seems to lack a sensible explanation, try recreating the database (or at least creating a new one) and scaffolding it with SchemaExport.

Answer 4

Add a method hascode() to your Entity Bean :

and retry it

TarHack

Answer 5

Confirmed, recreating database solves this problem!!!