JPA - Persisting a Unidirectional One to Many relationship fails with EclipseLink

Question

I'm trying to persist a very simple Unidirectional One to Many relationship, but EclipseLink (2.3.1) fails.

Service Class (Parent):

@Entity
@Table(name = "tbl_service2")
public class Service implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="service_id")
    public long serviceID;

    @Column(name="name")
    public String name;

    @OneToMany(cascade={CascadeType.ALL})
    @JoinColumn(name="service_id", referencedColumnName="service_id")
    public Set<Parameter> parameters;
}

Parameter Class (Child):
(Of course there is "service_id" foreign key field in the database, which is not represented in the class, as it's unidirectional relation).

@Entity
@Table(name = "tbl_service_parameters2")
public class Parameter implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="param_id")
    public long parameterID;

    @Column(name="name")
    public String name;
}

And this is the code for Entity persistence:

    Service service = new Service();
    service.parameters = new HashSet<Parameter>();
    service.name = "test";
    Parameter param = new Parameter();
    param.name = "test";
    service.parameters.add(param);
    em.persist(service);
    em.flush();

I get this exception:

Internal Exception: java.sql.SQLException: Field 'service_id' doesn't have a default value
Error Code: 1364
Call: INSERT INTO tbl_service_parameters2 (name) VALUES (?)
    bind => [test]

EDIT: The database field service_id has (and should have) not-null constraint, due the nature of the data.

Is this a bug or is something wrong in the code?

Answer 1

Try removing the not null constraint on the Parameter table's service_id field. Eclipselink will update the foreign key for unidirectional 1:m join columns in a separate statement, so you'll need to disable or delay the constraint check. Making it bidirectional will allow the fp field to be updated with the rest of the parameter data.