@PrimaryKeyJoinColumn: no insertable and no updatable

[Karsten Wutzke]

Hello,

why doesn't @PrimaryKeyJoinColumn/s have insertable = x and updatable = x ?

This would imply that if there are any properties to be flagged as "not insertable" and/or "not updatable" should go to the (column) properties marked with @Column rather than the conflicting associations tagged with @JoinColumn/s, right? The question is basically: where do the insertable and/or updatable best go to, the associations or the respective column properties?

Karsten

[James Sutherland]

Basically because a PrimaryKeyJoinColumn is always read-only (insertable/updateable=false). It only purpose is to be used when the primary key is mapped using a basic attribute. The basic attribute is responsible for mapping it.

See,
http://en.wikibooks.org/wiki/Java_Persistence/Identity_and_Sequencing#Primary_Keys_through_OneToOne_Relationships

In JPA 2.0 you don't need the basic, so can just use the JoinColumn with an @Id on it.
If you want both, and want the OneToOne writable, then use a JoinColumn and make the Id's column insertable/updateable=false.

[Karsten Wutzke]

(I've already read the wikibooks article a thousand times.)

OK, this is what I suspected. Your statement "@PrimaryKeyJoinColumn is always read-only" makes perfect sense to me. However, I have the following mapping which gives me headaches with your answer. (I'm in a JPA 1.0 environment (JavaEE 5) with Hibernate 3.5.4)

Table first:

CREATE TABLE Scores
(
  game_id INTEGER,
  is_home BOOLEAN,
  roster_id INTEGER,
  final_score SMALLINT,
  PRIMARY KEY (game_id, is_home),
  FOREIGN KEY (game_id) REFERENCES Games (id)
  FOREIGN KEY (roster_id) REFERENCES Rosters (id)
)

As you can see there's a composite PK on the table with game_id being an FK column to Games.id. is_home is a simple PK column which goes into the PK class. That's about it. Here's the (generated) JPA 1.0 code:

@Entity
@Table(name = "Scores")
public class Score implements Serializable
{
	@EmbeddedId
	private ScoreId id;

	@Column(name = "final_score")
	private Integer finalScore = null;

	@ManyToOne
	@PrimaryKeyJoinColumn(name = "game_id", referencedColumnName = "id")
	private Game game = null;

	@ManyToOne
	@JoinColumn(name = "roster_id", referencedColumnName = "id")
	private Roster roster = null;
...

Composite PK class using @EmbeddedId:

@Embeddable
public class ScoreId implements Serializable
{
	@Column(name = "game_id", insertable = false, updatable = false)
	private Integer gameId;

	@Column(name = "is_home")
	private Boolean isHome;
...

Hibernate 3.5.4 produces a stack trace on calling Persistence.createEntityManagerFactory("bbstats"):

org.hibernate.MappingException: Repeated column in mapping for entity: com.kawoolutions.bbstats.model.Score column: game_id (should be mapped with insert="false" update="false")
	org.hibernate.mapping.PersistentClass.checkColumnDuplication(PersistentClass.java:676)
	org.hibernate.mapping.PersistentClass.checkPropertyColumnDuplication(PersistentClass.java:698)
	org.hibernate.mapping.PersistentClass.checkColumnDuplication(PersistentClass.java:720)
	org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:474)
	org.hibernate.mapping.RootClass.validate(RootClass.java:236)
	org.hibernate.cfg.Configuration.validate(Configuration.java:1193)
	org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1378)
	org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:954)
	org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:891)
	org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:57)
	javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:48)
	javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:32)
	com.kawoolutions.bbstats.servlet.BasketballStatsServlet.doGet(BasketballStatsServlet.java:88)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

Hibernate is complaining about game_id not being insertable=false and updatable=false. According to your statement and my suspicion the @PrimaryKeyJoinColumn should do just that. Note, that I put the insertable = false, updatable = false on the ID class' game_id property, because when using an @IdClass implementation instead of @EmbeddedId "insertable = false, updatable = false" is put into the redundant column's @Id annotation, too. (it might be wrong to do so)

I was able to get rid of the Hibernate exception by using

@ManyToOne
@PrimaryKeyJoinColumn(name = "game_id", referencedColumnName = "id", insertable = false, updatable = false)
private Game game = null;

to give:

@Entity
@Table(name = "Scores")
public class Score implements Serializable
{
	@EmbeddedId
	private ScoreId id;

	@Column(name = "final_score")
	private Integer finalScore = null;

	@ManyToOne
	@JoinColumn(name = "game_id", referencedColumnName = "id", insertable = false, updatable = false)
	private Game game = null;

	@ManyToOne
	@JoinColumn(name = "roster_id", referencedColumnName = "id")
	private Roster roster = null;

...

This however means one of two things:

1. Your statement and my suspicion are wrong.
or
2. Hibernate has an issue correctly interpreting @PrimaryKeyJoinColumn

It raises the question for me, as I'm trying to create JPA 1.0 code to be used with Hibernate, if Hibernate 3.x can be used in a JPA 1.0 environment at all.

See: http://www.coderanch.com/t/509568/ORM/java/Hibernate-JPA

For me, it's a mystery why

@PrimaryKeyJoinColumn(name = "game_id", referencedColumnName = "id")
and
@JoinColumn(name = "game_id", referencedColumnName = "id", insertable = false, updatable = false)

aren't the same in Hibernate 3.5 and/or 3.6 (assuming JPA 1.0, which doesn't allow adding @Id to @XToX associations)...

Comments?

Karsten