Using primary key of one table as foreign key to another table

Question

Lets say I have the following SQL table definitions:

create table overview (
   key          bigserial not null,
   supplemental decimal(20) not null,
   constraint overview_pk primary key (key)
);
create table details (
   key        decimal(20) not null,
   ver        decimal(20) not null,
   constraint details_pk primary key (key, ver)
);

Furthermore I have two appropriate JPA mapping classes like this:

@Entity
@Table(name = "overview")
public class Overview implements Serializable {
  private static final long serialVersionUID = 1L;

  @Id
  @GeneratedValue(strategy = GenerationType.SEQUENCE)
  @Column(name = "key", unique = true, nullable = false)
  private BigDecimal key;

  @Column(nullable = false)
  private BigDecimal supplemental;

  @OneToOne(mappedBy = "overview")
  private Details details;

  public Overview() {
  }

  public Overview(BigDecimal supplemental, Details details) {
    this.details = details;
    this.details.setOverview(this);
  }

@Entity
@Table(name = "details")
public class Details implements Serializable {
  private static final long serialVersionUID = 1L;

  @Id
  @Column(name = "key", nullable = false)
  protected BigDecimal key;

  @Column(name = "ver", nullable = false)
  protected BigDecimal ver;

  @OneToOne(fetch = FetchType.LAZY)
  @MapsId(value = "key")
  private Overview overview;

  public Details() {
  }

  public Overview getOverview() {
    return overview;
  }

  public void setOverview(Overview overview) {
    this.overview = overview;
  }


}

The intention is to have a single key generation in Table overview and use that key for two things. First as foreign key in details table and as primary key for overview table as well.

One question is: Is this possible with Hibernate / Spring Data JPA? Based on what I have read it should be?

I have some test code which save things into overview, details tables but always fail with a error message like this:

nested exception is java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: 
object references an unsaved transient instance - save the transient instance before flushing 
: xyz.modell.Overview.details 
-> xyz.modell.Details

Maybe someone has an idea what I'm doing wrong?

overview table has a pk on key column and details table has pk on key and ver columns which is a combination key. So referring pk of overview table as foreign key in details table is not possible for a combination key on (key, ver). — Suresh, Feb 13 '18 at 14:21
The duplicate to the question in the title is: https://stackoverflow.com/questions/27305950/jpa-foreign-key-that-is-also-a-primary-key-mapping — Jens Schauder, Feb 15 '18 at 06:58
The `details` table has a composite primary key - jpa should reflect that. I remember doing this "one part of the composite primary key is a foreign key" thing once (hence, it's possible) but... do not do it: just add a unique id to your `details` table and change the primary key to an unique index: you'll live a happier life — giorgiga, Feb 15 '18 at 07:01

Using primary key of one table as foreign key to another table

0 Answers0