Share columns between composite key and @ManyToOne JoinColumns

Question

I'm having a problem that I don't know if it's possible to solve just by using hibernate/jpa annotations. The problem is that I have a composite key that has the same column as one of my foreignkey composite id, and I would like to share this same column on the table. For example:

@Entity
class Id {
  @Id
  @Column(name = "idPessoa")
  public Integer idShared;
}

@Embeddable
class APK {
  @ManyToOne
  @JoinColumn(name = "idShared")
  public Id idShared;
  public String nKey;
}

@Entity
class A {
  @EmbeddedId
  public APK id;
}

@Embeddable
class BPK {
  @ManyToOne
  @JoinColumn(name = "idShared")
  public Id idShared;
  public Integer nCode;
}

@Entity
class B {
  @EmbeddedId
  public BPK id;

  @ManyToOne
  @JoinColumns({ @JoinColumn(name = "idShared", nullable = false, insertable = false, updatable = false), @JoinColumn(name = "nKey", nullable = false) })
  public A a;
}

The question is how I can share the column idShared between A and B and use it in the @ManyToOne for the foreign key?

I already tried to use @JoinColumn inside @JoinColumns with the name idShared but I get an error saying that I need to use insert = false and update = false, I already put insertable = false and updateable = false, but then I get another error saying that I can't mix things.

I found a possible solution saying to use:

@ManyToOne
@JoinColumnsOrFormulas(value = {
@JoinColumnOrFormula(formula = @JoinFormula(value = "idShared", referencedColumnName = "idShared")),
@JoinColumnOrFormula(column = @JoinColumn(name = "nKey", nullable = false)) })
public A a;

But it gives me the error:

Unable to find column with logical name  in table A

It appears that the "name" property of the column it has to find is blank someway.

Need some help please!

cant you make another class like idshared that have your shared id, and then join it to bpk and apk? — Angga
In fact in my current code idShared is a ForeignKey to another class, and both apk and bpk have this foreign key to idShared, but the problem is that I can't see how to share the same column when I want to make a FK to A inside B — loop0.brs
I think the solution is with JoinFormula thing, but I can't find documentation on how it works — loop0.brs

gerrytan gerrytan · Accepted Answer · 2013-07-05T05:13:31

Please have a look at Official Java EE 6 Tutorial about composite primary key. You can use @EmbeddedId @Embeddable and/or @IdClass annotations.

For example

// File: APK.java ---------------------
@Embeddable
public class APK implements Serializable {
  public Integer idShared;
  public String nKey;
}

// File: A.java ---------------------    
@Entity
public class A {
  @EmbeddedId public APK id;
}

Share columns between composite key and @ManyToOne JoinColumns

1 Answers