How to map a table without ID, using Hibernate annnotaions?

Question

Hello, good morning, sir. Having a table that relates USER and ACHIEVEMENTS called USER_ACHIEVEMENTS, where it does not have ID, only USER_ID and ACHIEVEMENTS_ID, ie a manyToMany relationship.

How to map this table in Hibernate, without it having an ID?

Follow my class Entity:

@Entity
@Table(name="USER_ACHIEVEMENTS")
public class UserAchievements {

@Column(name="USER_ID", nullable=false)
private int userId;

@Column(name="ACHIEVEMENTS_ID", nullable=false)
private int achievementsId;

When running the project, with this class mapped this way, the error below happens:

Caused by: org.hibernate.Annotationexception: No Identifier specified for Entity: com.poli.server.PoliServer.Model.Userachievements

Answer 1

To create a Many to Many mapping you can map your entities in this way, without any need to transform your associative table into a java object.

@Entity
@Table(name="notebook")
public class Notebook {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;
    private String serialNumber;
    private int ramMemoryTotal;
    private int hdSpaceTotal;

    //Relacionamento implementado
    @ManyToMany(mappedBy="notebooks")
    private List pessoas
}

In Person I do the following:

@Entity
@Table(name = "Pessoa")
@SecondaryTable(name = "health_care", pkJoinColumns = 
{ @PrimaryKeyJoinColumn(name = "id") })
public class Pessoa {

    @Id
    private int id;

    @Column
    private String name;

    @Column(table = "health_care", name = "company_name")
    private String companyName;

    @ManyToMany
    @JoinTable(name="pessoa_has_notebooks", joinColumns=
    {@JoinColumn(name="pessoa_id")}, inverseJoinColumns=
      {@JoinColumn(name="notebook_id")})
    private List notebooks;
  }