JPA many to many with extra column

Question

I have a following problem that I need to solve. The core issues is that I want to add additional column into JoinTable for ManyToMany relation in JPA. In my case I have fol

Answer 1

One technique that is useful when creating the many-to-many mapping class entity is to attribute the id's in the class along with @ManyToOne designation which makes this class act as the composite key class:

@Entity
@Table(name = "market_vendor")
public class MarketVendor implements Serializable 
{
  @Id
  @ManyToOne
  @JoinColumn(name = "market_id")
  private Market market;

  @Id
  @ManyToOne
  @JoinColumn(name = "vendor_id")
  private Vendor vendor;

  @Basic
  @Column(name="active")
  private boolean active;

  public MarketVendor(Market market, Vendor vendor, boolean active)
  {
    this.market = market;
    this.vendor = vendor;
    this.active = active;
  }
}

This allows you to have the composite primary key defined within the same class without having to have a separate primary key class. You also need to make the class serializable.