Spring and JPA 2.0 - Single value Primary Key through OneToOne

Question

I have a simple table (ActivityLog) and I want it to have a PK that is also a FK to another table (User).

It seems to be a common thing to have, and I tried to follow this wikibook Primary Keys through OneToOne and ManyToOne Relationships . The example there involved a composite key. I need just a primitive key, so I ended up with:

@Entity
public class User {
 @Id
 private Long id;

 // other stuff
}

@Entity
public class ActivityLog {
 @Id
 @OneToOne(optional = false)
 @JoinColumn(name="user_id", referencedColumnName="id")
 private User user;

 // other stuff
}

Unfortunately i am getting:

Caused by: java.lang.IllegalArgumentException: This class [class com.example.ActivityLog] does not define an IdClass
at org.hibernate.metamodel.internal.AbstractIdentifiableType.getIdClassAttributes(AbstractIdentifiableType.java:183)
at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation$IdMetadata.<init>(JpaMetamodelEntityInformation.java:253)

I tried to annotate ActivityLog with:

 @IdClass(Long.class)

(even though from what I understand it is applicable only for composite keys), yet I am getting the exact same error.

Is my case different than what's on the mentioned wikibook?

Is Spring at fault here? (As suggested in this question? (no accepted answers)).

Answer 1

This should help:

@Entity
public class ActivityLog {

   @Id
   @Column(name = "user_id")
   private Long id;

   @OneToOne(optional = false)
   @JoinColumn(name="user_id", referencedColumnName="id")
   private User user;

   // other stuff
}

Btw. I would expect, that you need more logs per user, so you would probably need some additional (generated) id anyway ...