Spring Hibernate：持久存在具有多对多关系和复合键的实体

Question

I have two entites linked by a many-to-many relationship , the owner of the relationship has a composite primary key which is a class annotated with @Emebbedable. Here are the entity classes :

Reservation.java :

@Entity
@NamedQuery(name="Reservation.findAll", query="SELECT r FROM Reservation r")
public class Reservation implements Serializable {
private static final long serialVersionUID = 1L;

@EmbeddedId
private ReservationPK id;

private int actif;

private String commentaire;

@Column(name="date_creation")
private Timestamp dateCreation;

@Column(name="date_liberation")
private Timestamp dateLiberation;

private int indice;

private String libelle;

private String nom;

//bi-directional many-to-many association to Composant
@LazyCollection(LazyCollectionOption.FALSE)
@ManyToMany
@JoinTable(
        name="resa_comp"
        , joinColumns={
                @JoinColumn(name="id_env", referencedColumnName="id_env"),
                @JoinColumn(name="id_reserv", referencedColumnName="id_reserv")
            }
        , inverseJoinColumns={
                @JoinColumn(name="id_comp")
            }
    )
@JsonBackReference
private List<Composant> composants;

// getters and setters ...

ReservationPK.java :

@Embeddable
public class ReservationPK implements Serializable {
//default serial version id, required for serializable classes.
private static final long serialVersionUID = 1L;

@Column(name="id_reserv")
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int idReserv;

@Column(name="id_env", insertable=false, updatable=false)
private int idEnv;

public ReservationPK() {
}
public int getIdReserv() {
    return this.idReserv;
}
public void setIdReserv(int idReserv) {
    this.idReserv = idReserv;
}
public int getIdEnv() {
    return this.idEnv;
}
public void setIdEnv(int idEnv) {
    this.idEnv = idEnv;
}

public boolean equals(Object other) {
    if (this == other) {
        return true;
    }
    if (!(other instanceof ReservationPK)) {
        return false;
    }
    ReservationPK castOther = (ReservationPK)other;
    return 
        (this.idReserv == castOther.idReserv)
        && (this.idEnv == castOther.idEnv);
}

public int hashCode() {
    final int prime = 31;
    int hash = 17;
    hash = hash * prime + this.idReserv;
    hash = hash * prime + this.idEnv;

    return hash;
}

Composant.java :

@Entity
@NamedQuery(name="Composant.findAll", query="SELECT c FROM Composant c")
public class Composant implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id_comp")
private int idComp;

@Size(max=250)
@Column(name="attribut_1")
private String attribut1;

@Size(max=250)
@Column(name="attribut_2")
private String attribut2;

@Size(max=250)
@Column(name="attribut_3")
private String attribut3;

@Size(max=250)
@Column(name="attribut_4")
private String attribut4;

@Size(max=250)
@Column(name="attribut_5")
private String attribut5;


//bi-directional many-to-many association to Reservation
@LazyCollection(LazyCollectionOption.FALSE)
@ManyToMany(mappedBy="composants")
@JsonManagedReference
private List<Reservation> reservations; 

when i try to persist an instance of Reservation containing a List of Composant by using getCurrentSession.save() i get this error :

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (`scott`.`resa_comp`, CONSTRAINT `fk_reservation_has_composant_reservation1` FOREIGN KEY (`id_reserv`, `id_env`) REFERENCES `reservation` (`id_reserv`, `id_env`) ON DELETE NO ACTION ON UPDATE N)

I can see in the log file that hibernate is trying to insert a record into the relationship table using an id_reserv = 0 is there any way to make hibernate use the correct id when inserting records into the relationship table ?

i tried to modify my save methode located in my service layer by trying to save the Reservation object first before linking the list of composant and then updating the reservation but i get the same error. for reference here are my DAO and service layer's save method :

saveDao :

 @Override
public Reservation save(Reservation r) {
    // TODO Auto-generated method stub
    ReservationPK idResaPK =  (ReservationPK)   this.sessionFactory.getCurrentSession().save(r);
    System.out.println("id resa saved = "+idResaPK.getIdReserv());
    return this.getById(idResaPK);
}

saveService :

    @Override
public Reservation save(Reservation r) {
    // TODO Auto-generated method stub
    if(r.getComposants().isEmpty()) {
        logger.info("you are here ! empty");
        return this.resDao.save(r);
    }
    else {
        logger.info("you are here ! full");
        List<Composant> listComp = new ArrayList<Composant>();
        listComp.addAll(r.getComposants());
        for (Composant composant : r.getComposants()) {
            //listComp.add(composant);
            composant.setReservations(new ArrayList<Reservation>());
        }
        r.setComposants(new ArrayList<Composant>());
        if( r.getComposants() != null) {
            for (Composant comp : r.getComposants()) {
                logger.info("you are here jsdhjshqdlkhdjh :"+comp.getNom());
            }
        }
        Reservation resaSaved = this.resDao.save(r);
        logger.info("done saving : "+resaSaved.getId().getIdReserv());
        resaSaved.setComposants(listComp);
        ArrayList<Reservation> resaList = new ArrayList<Reservation>();
        resaList.add(r);
        for (Composant compo : listComp) {
            compo.setReservations(resaList);
        }
        this.resDao.update(resaSaved);
        logger.info("done updating");
        return r;

    }

}

Thanks in advance.

Answer 1

change the data types of properties marked with @Id annotation to primitive wrapper classes wherever primitive data type is used as primary key. While saving a new entity, id property will have value zero whereas when primitive wrapper is used value will be NULL. While persisting new entity , id value should be null whereas here it is 0.

Do the following changes:

//ReservationPK class
@Column(name="id_reserv")
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Integer idReserv;//instead of int

@Column(name="id_env", insertable=false, updatable=false)
private Integer idEnv;//instead of int

//Composant class
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id_comp")
private Integer idComp; //instead of int