Bidirectional OneToOne

mbarker · **Joined:** Wed Mar 28, 2007 4:00 pm **Posts:** 7

I have followed the examples, but have never been able to get a Bidirectional OneToOne association to work.

Code:

@Entity
public class Server implements Serializable {
    
    private int serverId;
    private Task task;
    
    @Id
    @Column(name="server_id")
    public int getServerId() {
        return serverId;
    }

    @OneToOne
    @PrimaryKeyJoinColumn
//    @JoinColumn(name="task_id")
    public Task getTask() {
        return task;
    }
}

@Entity
public class Task implements Serializable {
    private int taskId;
    private Server server;

    @Id
    @Column(name="task_id")
    public int getTaskId() {
        return taskId;
    }

    @OneToOne(mappedBy = "server_id")
    public Server getServer() {
        return server;
    }
}

hibernatetool always gets a NullPointerException with the above code. If I comment out the getServer method and annotation, then I have a unidirectional association, but I still get the following error from hibernate tool:

hibernatetool org.hibernate.tool.hbm2x.ExporterException: Error while processing template hbm/hibernate-mapping.hbm.ftl
hibernatetool freemarker.template.TemplateException: Error reading included file hbm/one-to-one.hbm.ftl
hibernatetool java.io.FileNotFoundException: Template hbm/one-to-one.hbm.ftl not found.

Furthermore, if I change PrimaryKeyJoinColumn to JoinColumn, then the unidirectional association finally works.

I'm using
Hibernate 3.2.2.ga
HibernateAnnotations 3.3.0.GA
HibernateTools 3.2.0.beta8
Freemarker 2.3.4

How do I get the bidirectional association to work correctly? What is the deal with the *.hbm.ftl files?

emmanuel · **Posted:** Tue Apr 17, 2007 10:03 am

it should be

@OneToOne(mappedBy = "task")

mbarker · **Joined:** Wed Mar 28, 2007 4:00 pm **Posts:** 7

This helps me understand that it is a logical mapping and not a physical mapping that I need.

However, I still get the errors
- org.hibernate.tool.hbm2x.ExporterException: Error while processing template hbm/hibernate-mapping.hbm.ftl
- freemarker.template.TemplateException: Error reading included file hbm/one-to-one.hbm.ftl

What am I missing? Where do these files reside?

Edmundo de Andrade · **Joined:** Mon Mar 17, 2008 3:07 pm **Posts:** 8

The following error message happens to me also whenever I try import hbm files that use one-to-one relationship:

freemarker.template.TemplateException: Error reading included file hbm/one-to-one.hbm.ftl

Actually, this message might be wrong once that template (ftl) is not in the standard hibernate tools package:

http://anonhibernate.labs.jboss.com/bra ... lates/hbm/

Please, someone explain that to us!