How to implements entity with 2 entity as primary key with jpa annotation and repository-CodePudding

i want to implement a many to many association with quantity information in it . like this :

@Entity
@Table(name = "reserves")
@Getter @Setter @NoArgsConstructor
public class Reserve {
    @Id
    @ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
    @JoinColumn(name = "groupe_id")
    private GroupeSanguin bloodGroup;
    @Id
    @ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
    private Banque banque;
    private int quantity;
}

the GroupSanguin and the Banque are two class stored in the database two . here is the code for the two if you need :

@Entity
@Table(name = "groupe_sanguins")
public class GroupeSanguin {
    @Id
    private String groupe;
    @OneToMany(mappedBy = "groupeSanguin")
    private List<Donneur> donneurs;
}
@Entity @Getter @Setter @NoArgsConstructor
public class Banque {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Column(unique = true,nullable = false)
    private String nom;
    private String adresse;
    @Column(unique = true)
    private String telephone;
    private String localisation;
}

so my i want to know how to annotate the JpaRepository to take the two as primary key like this and is my annotation good for it to work ?

public interface ReserveRepository extends JpaRepository<
Reserve,
//what to put here ?
>

CodePudding user response：

This isn't a JPA question in fact, it's a relationnal database conception. If Reserve has is own data and links with other entity it has it own Id You can add unicity constraint

@Entity
@Table(name = "reserves", uniqueConstraints={
@UniqueConstraint(columnNames = {"banque_id", "groupe_id"})
@Getter @Setter @NoArgsConstructor
public class Reserve {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
   

@ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
@JoinColumn(name = "groupe_id")
private GroupeSanguin bloodGroup;
   
@ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
@JoinColumn(name = "banque_id")
private Banque banque;
private int quantity;

}

CodePudding user response：

i've found this solutions too.

@Entity
@Table(name = "reserves")
@Getter @Setter @NoArgsConstructor
@IdClass(ReserveId.class) //this annotation will tell that id that the 
// the id will be represented by a class
public class Reserve {
    @Id
    @ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
    @JoinColumn(name = "groupe_id")
    private GroupeSanguin groupeSanguin;
    @Id
    @ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
    @JoinColumn(name = "banque_id")
    private Banque banque;
    private int quantity;
}

and the id class should implements Serializable like this :

@Getter @Setter
public class ReserveId implements Serializable {
    private Banque banque;
    private GroupeSanguin groupeSanguin;
}

and finally the repository will be like that :

@Repository
public interface ReserveRepo extends JpaRepository<Reserve, ReserveId>{}