Hibernate Road 3

@ManyToMany UserDetails a Vehicle y @ManyToMany Vehicle a UserDetails

Establezcamos una relación de muchos a muchos de UserDetails a Vehicle y viceversa, en otras palabras usuario puede tener varios vehículos, y también un vehículo puede tener varios usuarios.

UserDetails.java

@Entity

@Table (name="USER_DETAILS")

public class UserDetails {

       @Id @GeneratedValue(generator="vehicle-gen",strategy=GenerationType.AUTO)

       @GenericGenerator(name="vehicle-gen",strategy="sequence",

                                         parameters={@Parameter(name="sequence_name",value="seq_vehicle")}

                                  )

       private int userId;

       private String userName;

       @ManyToMany

       private Collection<Vehicle> vehicle = new ArrayList<Vehicle>();

setters y getters…

en Vehicle.java

@Entity

public class Vehicle {

       @Id @GeneratedValue(strategy=GenerationType.AUTO)

       private int vehicleId;

       private String vehicleName;

       @ManyToMany

       private Collection<UserDetails> userList = new ArrayList<UserDetails>();

En HibernateTest.java cargaremos datos a user y a vehicle.

public static void main(String[] args) {

             UserDetails userDetails = new UserDetails();

                          

             Vehicle vehicle1 = new Vehicle();

             vehicle1.setVehicleName("carrito");

             Vehicle vehicle2 = new Vehicle();

             vehicle2.setVehicleName("Audi");

                          

             userDetails.setUserName("Primer Usuario");

             userDetails.getVehicle().add(vehicle1);

             userDetails.getVehicle().add(vehicle2);

            

             vehicle1.getUserList().add(userDetails);

             vehicle2.getUserList().add(userDetails);

            

             SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

             Session session = sessionFactory.openSession();

             session.beginTransaction();

             session.save(userDetails);

             session.save(vehicle1);

             session.save(vehicle2);

             session.getTransaction().commit();

             session.close();

            

             //sessionFactory.close();

       }

 Al ejecutar el programa. Hibernate reporta en la consola, la creación de dos tablas de relación.

Hibernate: drop table if exists seq_vehicle

Hibernate: drop table if exists USER_DETAILS

Hibernate: drop table if exists USER_DETAILS_Vehicle

Hibernate: drop table if exists Vehicle

Hibernate: drop table if exists Vehicle_USER_DETAILS

Hibernate: create table hibernate_sequence (next_val bigint) engine=MyISAM

…

Hibernate: insert into hibernate_sequence values ( 1 )

Hibernate: create table seq_vehicle (next_val bigint) engine=MyISAM

Hibernate: insert into seq_vehicle values ( 1 )

Hibernate: create table USER_DETAILS (userId integer not null, userName varchar(255), primary key (userId)) engine=MyISAM

Hibernate: create table USER_DETAILS_Vehicle (UserDetails_userId integer not null, vehicle_vehicleId integer not null) engine=MyISAM

Hibernate: create table Vehicle (vehicleId integer not null, vehicleName varchar(255), primary key (vehicleId)) engine=MyISAM

Hibernate: create table Vehicle_USER_DETAILS (Vehicle_vehicleId integer not null, userList_userId integer not null) engine=MyISAM

Hibernate: alter table USER_DETAILS_Vehicle add constraint FKd6kp2c4oltmpsg6g9d8u15ymw foreign key (vehicle_vehicleId) references Vehicle (vehicleId)

Hibernate: alter table USER_DETAILS_Vehicle add constraint FKbdrxqw3j8dovf9npdkrfkpc3u foreign key (UserDetails_userId) references USER_DETAILS (userId)

Hibernate: alter table Vehicle_USER_DETAILS add constraint FK8t4fr6s5yx5sg3qquujrjn2w2 foreign key (userList_userId) references USER_DETAILS (userId)

Hibernate: alter table Vehicle_USER_DETAILS add constraint FK8mnn7v8pd5lo5asfwtvuwbfp3 foreign key (Vehicle_vehicleId) references Vehicle (vehicleId)

…

Hibernate: select next_val as id_val from seq_vehicle for update

Hibernate: update seq_vehicle set next_val= ? where next_val=?

Hibernate: select next_val as id_val from hibernate_sequence for update

Hibernate: update hibernate_sequence set next_val= ? where next_val=?

Hibernate: select next_val as id_val from hibernate_sequence for update

Hibernate: update hibernate_sequence set next_val= ? where next_val=?

Hibernate: insert into USER_DETAILS (userName, userId) values (?, ?)

Hibernate: insert into Vehicle (vehicleName, vehicleId) values (?, ?)

Hibernate: insert into Vehicle (vehicleName, vehicleId) values (?, ?)

Hibernate: insert into USER_DETAILS_Vehicle (UserDetails_userId, vehicle_vehicleId) values (?, ?)

Hibernate: insert into USER_DETAILS_Vehicle (UserDetails_userId, vehicle_vehicleId) values (?, ?)

Hibernate: insert into Vehicle_USER_DETAILS (Vehicle_vehicleId, userList_userId) values (?, ?)

Hibernate: insert into Vehicle_USER_DETAILS (Vehicle_vehicleId, userList_userId) values (?, ?)

Tabla UserDetails

userId	userName
1	Primer Usuario

Tabla Vehicle

vehicleId	vehicleName
1	carrito
2	Audi

Tabla Vehicle_USER_DETAILS

Vehicle_vehicleId	userList_userId
1	1
2	1

Tabla USER_DETAILS_Vehicle

UserDetails_userId	vehicle_vehicleId
1	1
1	2

Se puede observar que es redundante una de las dos tablas de relación que creo hibernate, con una sola sería suficiente, pare ello hay que indicar en la entidad que no queremos que genere la tabla de relación redundante Vehicle con @ManyToMany(mappedBy="vehicle").

@ManyToMany(mappedBy=”…”)

En Vehicle.java, indicamos con mappedBy=”vehicle” que use la propiedad “vehicle” de UserDetails.

@Entity

public class Vehicle {

       @Id @GeneratedValue(strategy=GenerationType.AUTO)

       private int vehicleId;

       private String vehicleName;

       @ManyToMany(mappedBy="vehicle")

       private Collection<UserDetails> userList = new ArrayList<UserDetails>();

       …     

Al ejecutar el programa de carga de prueba HibernateTest.java, observamos que ahora solo que crea una sola table de relación USER_DETAILS_Vehicle

Hibernate: drop table if exists hibernate_sequence

…

Hibernate: drop table if exists seq_vehicle

Hibernate: drop table if exists USER_DETAILS

Hibernate: drop table if exists USER_DETAILS_Vehicle

Hibernate: drop table if exists Vehicle

Hibernate: create table hibernate_sequence (next_val bigint) engine=MyISAM

…

Hibernate: insert into hibernate_sequence values ( 1 )

Hibernate: create table seq_vehicle (next_val bigint) engine=MyISAM

Hibernate: insert into seq_vehicle values ( 1 )

Hibernate: create table USER_DETAILS (userId integer not null, userName varchar(255), primary key (userId)) engine=MyISAM

Hibernate: create table USER_DETAILS_Vehicle (userList_userId integer not null, vehicle_vehicleId integer not null) engine=MyISAM

Hibernate: create table Vehicle (vehicleId integer not null, vehicleName varchar(255), primary key (vehicleId)) engine=MyISAM

Hibernate: alter table USER_DETAILS_Vehicle add constraint FKd6kp2c4oltmpsg6g9d8u15ymw foreign key (vehicle_vehicleId) references Vehicle (vehicleId)

Hibernate: alter table USER_DETAILS_Vehicle add constraint FK8a2f131hek5akrmni3vff2ivy foreign key (userList_userId) references USER_DETAILS (userId)

…

Hibernate: select next_val as id_val from seq_vehicle for update

Hibernate: update seq_vehicle set next_val= ? where next_val=?

Hibernate: select next_val as id_val from hibernate_sequence for update

Hibernate: update hibernate_sequence set next_val= ? where next_val=?

Hibernate: select next_val as id_val from hibernate_sequence for update

Hibernate: update hibernate_sequence set next_val= ? where next_val=?

Hibernate: insert into USER_DETAILS (userName, userId) values (?, ?)

Hibernate: insert into Vehicle (vehicleName, vehicleId) values (?, ?)

Hibernate: insert into Vehicle (vehicleName, vehicleId) values (?, ?)

Hibernate: insert into USER_DETAILS_Vehicle (userList_userId, vehicle_vehicleId) values (?, ?)

Hibernate: insert into USER_DETAILS_Vehicle (userList_userId, vehicle_vehicleId) values (?, ?)

@ManyToOne @NotFound(NotFoundAction.IGNORE)

Utilizado para cuando se quiere evitar una exception cuando no se encuentra la entidad.

CascadeTypes 

En acciones como guardar, actualizar sobre una entidad con entidades hijas como propiedades sobre las cuales se desea que dicha acción se aplique también a estas entidades hijas. en este ejemplo guardamos userDetails pero no vehicle, es entonces cuando se genera un error
object references an unsaved transient instance...

@OneToMany 

@Entity

@Table (name="USER_DETAILS")

public class UserDetails {

       @Id @GeneratedValue(generator="vehicle-gen",strategy=GenerationType.AUTO)

       @GenericGenerator(name="vehicle-gen",strategy="sequence",

                                         parameters={@Parameter(name="sequence_name",value="seq_vehicle")}

                                  )

       private int userId;

       private String userName;

       @OneToMany

       @JoinTable(name="USER_VEHICLE",joinColumns=@JoinColumn(name="USER_ID"),

                    inverseJoinColumns=@JoinColumn(name="VEHICLE_ID"))

       private Collection<Vehicle> vehicle = new ArrayList<Vehicle>();

@Entity

public class Vehicle {

       @Id @GeneratedValue(strategy=GenerationType.AUTO)

       private int vehicleId;

       private String vehicleName;

public static void main(String[] args) {

             UserDetails userDetails = new UserDetails();

                          

             Vehicle vehicle1 = new Vehicle();

             vehicle1.setVehicleName("carrito");

             Vehicle vehicle2 = new Vehicle();

             vehicle2.setVehicleName("Audi");

                          

             userDetails.setUserName("Primer Usuario");

             userDetails.getVehicle().add(vehicle1);

             userDetails.getVehicle().add(vehicle2);

            

            

             SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

             Session session = sessionFactory.openSession();

             session.beginTransaction();

             session.save(userDetails);

             //session.save(vehicle1);

             //session.save(vehicle2);

             session.getTransaction().commit();

             session.close();

            

             //sessionFactory.close();

       }

may 31, 2018 2:30:30 PM org.hibernate.internal.ExceptionMapperStandardImpl mapManagedFlushFailure

ERROR: HHH000346: Error during managed flush [org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance beforeQuery flushing: org.bext.dto.Vehicle]

Exception in thread "main" java.lang.IllegalStateException: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance beforeQuery flushing: org.bext.dto.Vehicle

…

Agregando @OneToMany(cascade=CascadeType.PERSIST)

 Al calificar con cascade=CascadeType.PERSIST, no es necesario indicar en el código que guarde las entidades vehicle, pero si hay que indicar que se hace un persist() en lugar de un save().

@Entity

@Table (name="USER_DETAILS")

public class UserDetails {

       @Id @GeneratedValue(generator="vehicle-gen",strategy=GenerationType.AUTO)

       @GenericGenerator(name="vehicle-gen",strategy="sequence",

                                         parameters={@Parameter(name="sequence_name",value="seq_vehicle")}

                                  )

       private int userId;

       private String userName;

       @OneToMany(cascade=CascadeType.PERSIST)

       @JoinTable(name="USER_VEHICLE",joinColumns=@JoinColumn(name="USER_ID"),

                    inverseJoinColumns=@JoinColumn(name="VEHICLE_ID"))

       private Collection<Vehicle> vehicle = new ArrayList<Vehicle>();

En HibernateTest.java, cambiamos save a persist.

             SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

             Session session = sessionFactory.openSession();

             session.beginTransaction();

             session.persist(userDetails);

             //session.save(vehicle1);

             //session.save(vehicle2);

             session.getTransaction().commit();

             session.close();

Implementando Herencia

Herencia es una característica común en lenguajes OOP, pero para modelos entidad relación no es materia común. Hibernate da algunas opciones para implementar herencia.

@Entity

public class DosRuedas extends Vehicle {

       private String Manubrio;

…setters y getters…

@Entity

public class CuatroRuedas extends Vehicle {

       private String volante;

…setters y getters…

HibernateTest.java

public static void main(String[] args) {

       Vehicle vehicle = new Vehicle();

       vehicle.setVehicleName("transporte");

       DosRuedas bicicleta = new DosRuedas();

       bicicleta.setVehicleName("birula");

       bicicleta.setManubrio("Manubrio de bicicleta");

       CuatroRuedas automovil = new CuatroRuedas();

       automovil.setVehicleName("Audi");

       automovil.setVolante("volante de automovil");

                          

       SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

       Session session = sessionFactory.openSession();

       session.beginTransaction();

       session.save(vehicle);

       session.save(bicicleta);

       session.save(automovil);

       session.getTransaction().commit();

       session.close();

            

       //sessionFactory.close();

}

Hibernate crea una única table con columnas extras referentes a las propiedades de las clases hijas.

Tabla Vehicle

DTYPE	vehicleId	vehicleName	Manubrio	volante
Vehicle	1	transporte	NULL	NULL
DosRuedas	2	birula	Manubrio de bicicleta	NULL
CuatroRuedas	3	Audi	NULL	volante de automovil

@Inheritance(strategy=InheritanceType.SINGLE_TABLE)

Configurando valores y nombres en SINGLE_TABLE

Vehicle.java

@Entity

@Inheritance(strategy=InheritanceType.SINGLE_TABLE)

@DiscriminatorColumn(

             name="Tipo_Vehiculo",

             discriminatorType=DiscriminatorType.STRING)

public class Vehicle {

       @Id @GeneratedValue(strategy=GenerationType.AUTO)

       private int vehicleId;

       private String vehicleName;

…

DosRuedas.java

@Entity

@DiscriminatorValue("Bicicleta")

public class DosRuedas extends Vehicle {

       private String Manubrio;

…

CuatroRuedas.java

@Entity

@DiscriminatorValue("Carro")

public class CuatroRuedas extends Vehicle {

       private String volante;

…

Con estas configuraciones, obtenemos la table Vehicle con nombre de columna de discriminación con nombre Tipo_Vehiculo y valores como “Bicicleta” y “Carro”

Tabla Vehiculo customizada

Tipo_Vehiculo	vehicleId	vehicleName	Manubrio	volante
Vehicle	1	transporte	NULL	NULL
Bicicleta	2	birula	Manubrio de bicicleta	NULL
Carro	3	Audi	NULL	volante de automovil

@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)

La estratégia que crea una tabla por clase, es configurada con la anotación mostrada en el titulo de este párrafo. Con esto no es necesaria la anotación @DiscriminationColumn en la entidad padre y @DiscriminationValue en las entidades hijas.

Vehicle.java

@Entity

@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)

public class Vehicle {

       @Id @GeneratedValue(strategy=GenerationType.AUTO)

       private int vehicleId;

       private String vehicleName;

…

DosRuedas.java

@Entity

public class DosRuedas extends Vehicle {

       private String Manubrio;

…

CuatroRuedas.java

@Entity

public class CuatroRuedas extends Vehicle {

       private String volante;

…

Tabla Vehicle

vehicleId	vehicleName
1	transporte

Tabla DosRuedas

vehicleId	vehicleName	Manubrio
2	birula	Manubrio de bicicleta

Tabla CuatroRuedas

vehicleId	vehicleName	volante
3	Audi	volante de automovil

@Inheritance(strategy=InheritanceType.JOINED)

Con la estratégia JOINED se crean tablas separadas por clase o entidad, y se relacionan con una columna clave, de tal forma que recuperar la información se hace por medio de un query join.

Vehicle.java

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public class Vehiculo {
    @Id
    @GeneratedValue
    private int Id;
    private String Name;

setters y getters

…

DosRuedas.java

@Entity

public class DosRuedas extends Vehiculo {

    private String Manubrio;

setters y getters

…

CuatroRuedas.java

@Entity

public class CuatroRuedas extends Vehiculo{

    private String volante;

setters y getters

…

Programa de Prueba

public class HibernateTest {

    public static void main(String[] args){

        EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("org.hibernate.tutorial.jpa");



        Vehiculo vehiculo = new Vehiculo();

        vehiculo.setName("Transporte");



        DosRuedas dosRuedas = new DosRuedas();

        dosRuedas.setName("bicicleta");

        dosRuedas.setManubrio("Manubrio de Bicicleta");



        CuatroRuedas cuatroRuedas = new CuatroRuedas();

        cuatroRuedas.setName("Audi");

        cuatroRuedas.setVolante("Volante de Audi");



        EntityManager entityManager = entityManagerFactory.createEntityManager();



        entityManager.getTransaction().begin();

        entityManager.persist(vehiculo);

        entityManager.persist(dosRuedas);

        entityManager.persist(cuatroRuedas);

        entityManager.getTransaction().commit();



        entityManagerFactory.close();



    }

}

Hibernate muestra en la consola

Hibernate: create table CuatroRuedas (volante varchar(255), Id integer not null, primary key (Id)) engine=MyISAM

Hibernate: create table DosRuedas (Manubrio varchar(255), Id integer not null, primary key (Id)) engine=MyISAM

Hibernate: create table Vehiculo (Id integer not null, Name varchar(255), primary key (Id)) engine=MyISAM

Hibernate: alter table CuatroRuedas add constraint FKhaimfgg1r4h57bbo2js59hqq2 foreign key (Id) references Vehiculo (Id)

Hibernate: alter table DosRuedas add constraint FKmdtgstld5lhffvuc9lx69xmhk foreign key (Id) references Vehiculo (Id)

Tue Jun 05 19:10:20 CDT 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

Hibernate: select next_val as id_val from hibernate_sequence for update

Hibernate: update hibernate_sequence set next_val= ? where next_val=?

Hibernate: insert into Vehiculo (Name, Id) values (?, ?)

Hibernate: insert into Vehiculo (Name, Id) values (?, ?)

Hibernate: insert into DosRuedas (Manubrio, Id) values (?, ?)

Hibernate: insert into Vehiculo (Name, Id) values (?, ?)

Hibernate: insert into CuatroRuedas (volante, Id) values (?, ?)

jun 05, 2018 7:10:20 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop

INFO: HHH10001008: Cleaning up connection pool [jdbc:mysql://localhost:3306/wsp?zeroDateTimeBehavior=convertToNull]

tabla Vehiculo

Id	Name
1	Transporte
2	bicicleta
3	Audi

Tabla DosRuedas

Manubrio	Id
Manubrio de Bicicleta	2

Tabla CuatroRuedas

Manubrio	Id
Manubrio de Bicicleta	2

La integración de los datos se hace con un join de las tablas

SELECT * FROM vehiculo 
JOIN cuatroruedas ON vehiculo.id = cuatroruedas.id;

Id	Name	volante	Id
3	Audi	Volante de Audi	3

SELECT * FROM vehiculo 
JOIN dosruedas ON vehiculo.id = dosruedas.id;

Id	Name	Manubrio	Id
2	bicicleta	Manubrio de Bicicleta	2

FinTexto