Hi,

(Note: I originally reported this on the forum, but the lack of response suggests this might be a bug in Hibernate Annotations or Hibernate; the forum topic is at: http://forum.hibernate.org/viewtopic.php?t=970823)

I hope it's not a misuse of Hibernate, but I'm trying to use @Id on @OneToOne, and this causes the following NPE when running hbm2ddl:
java.lang.NullPointerException
at org.hibernate.util.StringHelper.qualify(StringHelper.java:264)
at org.hibernate.cfg.OneToOneSecondPass.doSecondPass(OneToOneSecondPass.java:196)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1130)
at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:296)
at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1115)
at org.hibernate.tool.ant.ConfigurationTask.getConfiguration(ConfigurationTask.java:56)
at org.hibernate.tool.ant.HibernateToolTask.getConfiguration(HibernateToolTask.java:287)
at org.hibernate.tool.ant.Hbm2DDLExporterTask.execute(Hbm2DDLExporterTask.java:45)
at org.hibernate.tool.ant.HibernateToolTask.execute(HibernateToolTask.java:171)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
at org.apache.tools.ant.Task.perform(Task.java:364)
at org.apache.tools.ant.Target.execute(Target.java:341)
at org.apache.tools.ant.Target.performTasks(Target.java:369)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
at org.apache.tools.ant.Project.executeTarget(Project.java:1185)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:40)
at org.apache.tools.ant.Project.executeTargets(Project.java:1068)
at org.apache.tools.ant.Main.runBuild(Main.java:668)
at org.apache.tools.ant.Main.startAnt(Main.java:187)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:246)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:67)



What I'm trying to do at the application level is:
Foo class and table
long foo_id, primary key
FooData fooData, nulllable=true


FooData class and table
foo_id references Foo(foo_id), nullable=false


This is expressed in Java as:
@Entity
@Table(name = "foo")
public class Foo {
   @Id @GeneratedValue
   @Column(name = "foo_id")
   Long id;

   @OneToOne(mappedBy = "foo", cascade = CascadeType.ALL)
   FooData fooData;
...
@Entity
@Table(name = "foo_data")
public class FooData {
   @Id
   @OneToOne
   @JoinColumn(name = "foo_id", nullable = false)
   Foo foo;



This causes a NPE here.

If I use a real Id on FooData, e.g.:
@Id
@Column(name = "foo_data_id")
Long id;

it works, and I end up with:
- foo_id in table foo as a primary key
- foo_data_id in table foo_data as a primary key
- foo_id in table foo_data not null
- foo_id in table foo_data references foo_id in table foo

I don't want a foo_data_id, I don't need it, hence the lack of it which leads to the NPE.

Bye,