JavaEE JPA API Laboratorio

JPA Cases

Estos Son ejemplos prácticos de generación de tablas de bases de datos a partir de entidades (@Entity)  annotations en Java JPA

Enlace a archivo work con imagenes

https://drive.google.com/open?id=0B3U2bXDcbfA1d0QwTGJBX0xrM1E

JPA_1_Simple Table

@Entity

public class Tabla implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String nombre;

    private String apellido;

    private Double valDouble;

    private Integer valInteger;

    private boolean valboolean;

    @Temporal(DATE)

    private java.util.Date utilDate;

    private java.sql.Date sqlDate;

    private Time sqlTime;

    private Timestamp sqlTimeStamp;

    @Lob

    private String descripcion;

    @Lob

    @Column(name="EMP_PIC",columnDefinition="BLOB NOT NULL")

    private byte[] pic;

   

    public Long getId() {

        return id;

    } …

Genera

drop table DEVELOP.TABLA cascade constraints;

/*==============================================================*/

/* Table: TABLA                                                 */

/*==============================================================*/

create table DEVELOP.TABLA

(

   ID                   NUMBER(19)           not null,

   APELLIDO             VARCHAR2(255),

   DESCRIPCION          CLOB,

   NOMBRE               VARCHAR2(255),

   EMP_PIC              BLOB                 not null,

   SQLDATE              DATE,

   SQLTIME              TIMESTAMP,

   SQLTIMESTAMP         TIMESTAMP,

   UTILDATE             DATE,

   VALDOUBLE            NUMBER(19,4),

   VALINTEGER           NUMBER(10),

   VALBOOLEAN           NUMBER(1)            default 0,

   constraint SYS_C007261 primary key (ID)

         using index pctfree 10

   initrans 2

   storage

   (

       initial 64K

       next 1024K

       minextents 1

       maxextents unlimited

   )

   logging

   tablespace DEVELOP_TABSPACE

)

pctfree 10

initrans 1

storage

(

    initial 64K

    next 1024K

    minextents 1

    maxextents unlimited

)

tablespace DEVELOP_TABSPACE

logging

 nocompress

 lob

 (DESCRIPCION)

    store as

         basicfile

 (tablespace DEVELOP_TABSPACE

        chunk 8192

 retention nocache);

drop table DEVELOP.SEQUENCE cascade constraints;

/*==============================================================*/

/* Table: SEQUENCE                                              */

/*==============================================================*/

create table DEVELOP.SEQUENCE

(

   SEQ_NAME             VARCHAR2(50)         not null,

   SEQ_COUNT            NUMBER,

   constraint SYS_C007263 primary key (SEQ_NAME)

         using index pctfree 10

   initrans 2

   storage

   (

       initial 64K

       next 1024K

       minextents 1

       maxextents unlimited

   )

   logging

   tablespace DEVELOP_TABSPACE

)

pctfree 10

initrans 1

storage

(

    initial 64K

    next 1024K

    minextents 1

    maxextents unlimited

)

tablespace DEVELOP_TABSPACE

logging

 nocompress

 monitoring

 noparallel;

JPA_2_SimpleTable

@Entity

public class Tabla implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator="TABLA_SEQ")

    @Column(name="TABLA_ID")

    private Long id;

    private String nombre;

…

drop table DEVELOP.TABLA cascade constraints;

/*==============================================================*/

/* Table: TABLA                                                 */

/*==============================================================*/

create table DEVELOP.TABLA

(

   TABLA_ID             NUMBER(19)           not null,

   APELLIDO             VARCHAR2(255),

   DESCRIPCION          CLOB,

   NOMBRE               VARCHAR2(255),

   EMP_PIC              BLOB                 not null,

   SQLDATE              DATE,

   SQLTIME              TIMESTAMP,

   SQLTIMESTAMP         TIMESTAMP,

   UTILDATE             DATE,

   VALDOUBLE            NUMBER(19,4),

   VALINTEGER           NUMBER(10),

   VALBOOLEAN           NUMBER(1)            default 0,

   constraint SYS_C007266 primary key (TABLA_ID)

         using index pctfree 10

   initrans 2

   storage

   (

       initial 64K

       next 1024K

       minextents 1

       maxextents unlimited

   )

   logging

   tablespace DEVELOP_TABSPACE

)

pctfree 10

initrans 1

storage

(

    initial 64K

    next 1024K

    minextents 1

    maxextents unlimited

)

tablespace DEVELOP_TABSPACE

logging

 nocompress

 lob

 (DESCRIPCION)

    store as

         basicfile

 (tablespace DEVELOP_TABSPACE

        chunk 8192

 retention nocache);

JPA_3_SimpleTable

@Entity

public class Tabla implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.TABLE, generator="TABLA_GEN")

    @Column(name="TABLA_ID")

    private Long id;

    private String nombre;

…

drop table DEVELOP.TABLA cascade constraints;

/*==============================================================*/

/* Table: TABLA                                                 */

/*==============================================================*/

create table DEVELOP.TABLA

(

   TABLA_ID             NUMBER(19)           not null,

   APELLIDO             VARCHAR2(255),

   DESCRIPCION          CLOB,

   NOMBRE               VARCHAR2(255),

   EMP_PIC              BLOB                 not null,

   SQLDATE              DATE,

   SQLTIME              TIMESTAMP,

   SQLTIMESTAMP         TIMESTAMP,

   UTILDATE             DATE,

   VALDOUBLE            NUMBER(19,4),

   VALINTEGER           NUMBER(10),

   VALBOOLEAN           NUMBER(1)            default 0,

   constraint SYS_C007269 primary key (TABLA_ID)

         using index pctfree 10

   initrans 2

   storage

   (

       initial 64K

       next 1024K

       minextents 1

       maxextents unlimited

   )

   logging

   tablespace DEVELOP_TABSPACE

)

pctfree 10

initrans 1

storage

(

    initial 64K

    next 1024K

    minextents 1

    maxextents unlimited

)

tablespace DEVELOP_TABSPACE

logging

 nocompress

 lob

 (DESCRIPCION)

    store as

         basicfile

 (tablespace DEVELOP_TABSPACE

        chunk 8192

 retention nocache);

drop table DEVELOP.SEQUENCE cascade constraints;

/*==============================================================*/

/* Table: SEQUENCE                                              */

/*==============================================================*/

create table DEVELOP.SEQUENCE

(

   SEQ_NAME             VARCHAR2(50)         not null,

   SEQ_COUNT            NUMBER,

   constraint SYS_C007271 primary key (SEQ_NAME)

         using index pctfree 10

   initrans 2

   storage

   (

       initial 64K

       next 1024K

       minextents 1

       maxextents unlimited

   )

   logging

   tablespace DEVELOP_TABSPACE

)

pctfree 10

initrans 1

storage

(

    initial 64K

    next 1024K

    minextents 1

    maxextents unlimited

)

tablespace DEVELOP_TABSPACE

logging

 nocompress

 monitoring

 noparallel;

JPA_4_SimpleTableElemColl

@Entity

public class Tabla implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.TABLE, generator="TABLA_GEN")

    @Column(name="TABLA_ID")

    private Long id;

    private String nombre;

    private String apellido;

    private Double valDouble;

    private Integer valInteger;

    private boolean valboolean;

    @Temporal(DATE)

    private java.util.Date utilDate;

    private java.sql.Date sqlDate;

    private Time sqlTime;

    private Timestamp sqlTimeStamp;

    @Lob

    private String descripcion;

    @Lob

    @Column(name="EMP_PIC",columnDefinition="BLOB NOT NULL")

    //@Column(name="EMP_PIC",columnDefinition="LONGBLOB NOT NULL") //en caso de MySQL

    private byte[] pic;

    @ElementCollection  //uses default table TABLA_ELEMCOLL

    @Column(name="DetalleTabla", length=50)

    private Set<String> ElemColl = new HashSet();

…

drop table DEVELOP.TABLA cascade constraints;

/*==============================================================*/

/* Table: TABLA                                                 */

/*==============================================================*/

create table DEVELOP.TABLA

(

   TABLA_ID             NUMBER(19)           not null,

   APELLIDO             VARCHAR2(255),

   DESCRIPCION          CLOB,

   NOMBRE               VARCHAR2(255),

   EMP_PIC              BLOB                 not null,

   SQLDATE              DATE,

   SQLTIME              TIMESTAMP,

   SQLTIMESTAMP         TIMESTAMP,

   UTILDATE             DATE,

   VALDOUBLE            NUMBER(19,4),

   VALINTEGER           NUMBER(10),

   VALBOOLEAN           NUMBER(1)            default 0,

   constraint SYS_C006999 primary key (TABLA_ID)

         using index pctfree 10

   initrans 2

   storage

   (

       initial 64K

       next 1024K

       minextents 1

       maxextents unlimited

   )

   logging

   tablespace DEVELOP_TABSPACE

)

pctfree 10

initrans 1

storage

(

    initial 64K

    next 1024K

    minextents 1

    maxextents unlimited

)

tablespace DEVELOP_TABSPACE

logging

 nocompress

 lob

 (DESCRIPCION)

    store as

         basicfile

 (tablespace DEVELOP_TABSPACE

        chunk 8192

 retention nocache);

alter table DEVELOP.TABLA_ELEMCOLL

   drop constraint TABLA_ELEMCOLL_TABLA_TABLA_ID;

drop table DEVELOP.TABLA_ELEMCOLL cascade constraints;

/*==============================================================*/

/* Table: TABLA_ELEMCOLL                                        */

/*==============================================================*/

create table DEVELOP.TABLA_ELEMCOLL

(

   TABLA_TABLA_ID       NUMBER(19),

   DETALLETABLA         VARCHAR2(50)

)

pctfree 10

initrans 1

storage

(

    initial 64K

    next 1024K

    minextents 1

    maxextents unlimited

)

tablespace DEVELOP_TABSPACE

logging

 nocompress

 monitoring

 noparallel;

alter table DEVELOP.TABLA_ELEMCOLL

   add constraint TABLA_ELEMCOLL_TABLA_TABLA_ID foreign key (TABLA_TABLA_ID)

      references DEVELOP.TABLA (TABLA_ID)

      not deferrable;

drop table DEVELOP.SEQUENCE cascade constraints;

/*==============================================================*/

/* Table: SEQUENCE                                              */

/*==============================================================*/

create table DEVELOP.SEQUENCE

(

   SEQ_NAME             VARCHAR2(50)         not null,

   SEQ_COUNT            NUMBER,

   constraint SYS_C007002 primary key (SEQ_NAME)

         using index pctfree 10

   initrans 2

   storage

   (

       initial 64K

       next 1024K

       minextents 1

       maxextents unlimited

   )

   logging

   tablespace DEVELOP_TABSPACE

)

pctfree 10

initrans 1

storage

(

    initial 64K

    next 1024K

    minextents 1

    maxextents unlimited

)

tablespace DEVELOP_TABSPACE

logging

 nocompress

 monitoring

 noparallel;

En caso de MySQL

drop table if exists wsp.tabla;

/*==============================================================*/

/* Table: tabla                                                 */

/*==============================================================*/

create table wsp.tabla

(

   TABLA_ID             bigint(20) not null,

   APELLIDO             national varchar(255),

   DESCRIPCION          national longtext,

   NOMBRE               national varchar(255),

   EMP_PIC              longblob not null,

   SQLDATE              date,

   SQLTIME              time,

   SQLTIMESTAMP         datetime,

   UTILDATE             date,

   VALDOUBLE            double,

   VALINTEGER           int(11),

   VALBOOLEAN           tinyint(1) default 0,

   primary key (TABLA_ID)

);

drop table if exists wsp.tabla_elemcoll;

/*==============================================================*/

/* Table: tabla_elemcoll                                        */

/*==============================================================*/

create table wsp.tabla_elemcoll

(

   Tabla_TABLA_ID       bigint(20),

   DetalleTabla         national varchar(50)

);

alter table wsp.tabla_elemcoll add constraint FK_Tabla_ELEMCOLL_Tabla_TABLA_ID foreign key (Tabla_TABLA_ID)

      references wsp.tabla (TABLA_ID);

drop table if exists wsp.sequence;

/*==============================================================*/

/* Table: sequence                                              */

/*==============================================================*/

create table wsp.sequence

(

   SEQ_NAME             national varchar(50) not null,

   SEQ_COUNT            decimal(38,0),

   primary key (SEQ_NAME)

);

JPA Relationships

ManyToOne Mappings

Employee(Many)   Department(One)

@Entity

public class Employee implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String name;

    private Long salary;

    @ManyToOne

    private Department department;

    …

}

@Entity

public class Department implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String name;

    …

}

DB scripts from Entity classes…

CREATE TABLE EMPLOYEE (ID NUMBER(19) NOT NULL, NAME VARCHAR2(255) NULL, SALARY NUMBER(19) NULL, DEPARTMENT_ID NUMBER(19) NULL, PRIMARY KEY (ID))

CREATE TABLE DEPARTMENT (ID NUMBER(19) NOT NULL, NAME VARCHAR2(255) NULL, PRIMARY KEY (ID))

ALTER TABLE EMPLOYEE ADD CONSTRAINT FK_EMPLOYEE_DEPARTMENT_ID FOREIGN KEY (DEPARTMENT_ID) REFERENCES DEPARTMENT (ID)

CREATE TABLE SEQUENCE (SEQ_NAME VARCHAR2(50) NOT NULL, SEQ_COUNT NUMBER(38) NULL, PRIMARY KEY (SEQ_NAME))

INSERT INTO SEQUENCE(SEQ_NAME, SEQ_COUNT) values ('SEQ_GEN', 0)

ManyToOne JoinColumn

@Entity

public class Employee implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String name;

    private Long salary;

    @ManyToOne

    @JoinColumn(name="DEPT_ID")

    private Department department;

    …

}

@Entity

public class Department implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String name;

    …

}

CREATE TABLE EMPLOYEE (ID NUMBER(19) NOT NULL, NAME VARCHAR2(255) NULL, SALARY NUMBER(19) NULL, DEPT_ID NUMBER(19) NULL, PRIMARY KEY (ID))

CREATE TABLE DEPARTMENT (ID NUMBER(19) NOT NULL, NAME VARCHAR2(255) NULL, PRIMARY KEY (ID))

ALTER TABLE EMPLOYEE ADD CONSTRAINT FK_EMPLOYEE_DEPT_ID FOREIGN KEY (DEPT_ID) REFERENCES DEPARTMENT (ID)

CREATE TABLE SEQUENCE (SEQ_NAME VARCHAR2(50) NOT NULL, SEQ_COUNT NUMBER(38) NULL, PRIMARY KEY (SEQ_NAME))

INSERT INTO SEQUENCE(SEQ_NAME, SEQ_COUNT) values ('SEQ_GEN', 0)

OneToOne Mappings

Employee (one) --- ParkingSpace (one)

@Entity

public class Employee implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String name;

    private Long salary;

    @OneToOne

    @JoinColumn(name="PSPACE_ID")

    private ParkingSpace parkingSpace;

    …

}

@Entity

public class ParkingSpace implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private int lot;

    private String location;

    …

}

CREATE TABLE EMPLOYEE (ID NUMBER(19) NOT NULL, NAME VARCHAR2(255) NULL, SALARY NUMBER(19) NULL, PSPACE_ID NUMBER(19) NULL, PRIMARY KEY (ID))

CREATE TABLE PARKINGSPACE (ID NUMBER(19) NOT NULL, LOCATION VARCHAR2(255) NULL, LOT NUMBER(10) NULL, PRIMARY KEY (ID))

ALTER TABLE EMPLOYEE ADD CONSTRAINT FK_EMPLOYEE_PSPACE_ID FOREIGN KEY (PSPACE_ID) REFERENCES PARKINGSPACE (ID)

CREATE TABLE SEQUENCE (SEQ_NAME VARCHAR2(50) NOT NULL, SEQ_COUNT NUMBER(38) NULL, PRIMARY KEY (SEQ_NAME))

INSERT INTO SEQUENCE(SEQ_NAME, SEQ_COUNT) values ('SEQ_GEN', 0)

Check that the foreing key must have a uniqueness constraint, and it doesn’t happen. So in case of MySQL is added manually the constraint

ALTER TABLE EMPLOYEE ADD UNIQUE PARKINGSPACECONSTRAINT (DEPT_ID);

In Oracle

ALTER TABLE EMPLOYEE ADD CONTRAINT PARKINGSPACECONSTRAINT UNIQUE (DEPT_ID)

When populate with data test report an error of duplicates.

OneToOne Bidirectional

@Entity

public class Employee implements Serializable { 

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String name;

    private Long salary;

    @OneToOne

    @JoinColumn(name="PSPACE_ID")

    private ParkingSpace parkingSpace;

@Entity

public class ParkingSpace implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private int lot;

    private String location;

    @OneToOne(mappedBy="parkingSpace")

    private Employee employee;

CREATE TABLE EMPLOYEE (ID NUMBER(19) NOT NULL, NAME VARCHAR2(255) NULL, SALARY NUMBER(19) NULL, PSPACE_ID NUMBER(19) NULL, PRIMARY KEY (ID))

CREATE TABLE PARKINGSPACE (ID NUMBER(19) NOT NULL, LOCATION VARCHAR2(255) NULL, LOT NUMBER(10) NULL, PRIMARY KEY (ID))

ALTER TABLE EMPLOYEE ADD CONSTRAINT FK_EMPLOYEE_PSPACE_ID FOREIGN KEY (PSPACE_ID) REFERENCES PARKINGSPACE (ID)

CREATE TABLE SEQUENCE (SEQ_NAME VARCHAR2(50) NOT NULL, SEQ_COUNT NUMBER(38) NULL, PRIMARY KEY (SEQ_NAME))

INSERT INTO SEQUENCE(SEQ_NAME, SEQ_COUNT) values ('SEQ_GEN', 0)

The generated script is the same as the OneToOne unidirection relation???

OneToMany

Employee (many) ---- Department (one)

@Entity

public class Employee implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String name;

    private Long salary;

    private Department department;

    …

}

@Entity

public class Department implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String name;

    @OneToMany(cascade=CascadeType.PERSIST,mappedBy="department") //(fetch=FetchType.LAZY, cascade=CascadeType.PERSIST)

    private List<Employee> employees = new ArrayList<Employee>();

    …

}

Script generated for MySQL:

CREATE TABLE EMPLOYEE (ID BIGINT NOT NULL, NAME VARCHAR(255), SALARY BIGINT, DEPARTMENT_ID BIGINT, PRIMARY KEY (ID))

CREATE TABLE DEPARTMENT (ID BIGINT NOT NULL, NAME VARCHAR(255), PRIMARY KEY (ID))

ALTER TABLE EMPLOYEE ADD CONSTRAINT FK_EMPLOYEE_DEPARTMENT_ID FOREIGN KEY (DEPARTMENT_ID) REFERENCES DEPARTMENT (ID)

CREATE TABLE SEQUENCE (SEQ_NAME VARCHAR(50) NOT NULL, SEQ_COUNT DECIMAL(38), PRIMARY KEY (SEQ_NAME))

INSERT INTO SEQUENCE(SEQ_NAME, SEQ_COUNT) values ('SEQ_GEN', 0)

OneToMany Version 2

@Entity

public class Employee implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.TABLE,generator="EMPLOYEE_GEN")

    @Column(name="EMP_ID")

    private Long id;

    private String name;

    private Long salary;

    @ManyToOne(targetEntity=Department.class, fetch=FetchType.LAZY)

    private Department department;

    …

}

@Entity

public class Department implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    @GeneratedValue(strategy = GenerationType.TABLE,generator="DEPARTMENT_GEN")

    @Column(name="DEP_ID")

    private Long id;

    private String name;

    @OneToMany(cascade=CascadeType.ALL,mappedBy="department") //(fetch=FetchType.LAZY, cascade=CascadeType.PERSIST)

    private List<Employee> employees = new ArrayList<Employee>();

     …

}

MySQL script:

ManyToMany with out CascadeType.Persist

@Entity

public class Employee implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    //@GeneratedValue(strategy = GenerationType.TABLE,generator="EMP_TAB")

    //@TableGenerator(name="EMP_TAB",table="EMP_GEN")

    @GeneratedValue(strategy=GenerationType.IDENTITY)

    @Column(name="EMP_ID")

    private Long id;

    private String name;

    private Long salary;

    @ManyToMany//(cascade = {CascadeType.PERSIST, CascadeType.MERGE})

    @JoinTable(name="EMP_PROJ",

            joinColumns=@JoinColumn(name="EMP_ID"),

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

    private List<Project> projects = new ArrayList<Project>();

   …

}

@Entity

public class Project implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id

    //@GeneratedValue(strategy = GenerationType.TABLE,generator="PROJ_TAB")

    //@TableGenerator(name="PROJ_TAB",table="PROJ_GEN")

    @GeneratedValue(strategy=GenerationType.IDENTITY)

    @Column(name="PROJ_ID")

    private Long id;

    private String name;

    @ManyToMany(mappedBy="projects")

    private List<Employee> employees = new ArrayList<Employee>();

    …

}

public class Populate {

    public static void main(String... args) {

        EntityManagerFactory emf = createEntityManagerFactory("JPArelationshipsPU");

        EntityManager em = emf.createEntityManager();

        populate(emf);

        emf.close();

    }

   

    private static void populate(EntityManagerFactory emf) {

        EntityManager em = emf.createEntityManager();

       

        Employee emp = new Employee();

        emp.setName("Un Empleado");

        emp.setSalary(1203L);

       

        Employee emp2 = new Employee();

        emp2.setName("Empleado Dos");

        emp2.setSalary(77777L);

       

        Employee emp3 = new Employee();

        emp3.setName("Empleado sin Departamento");

        emp3.setSalary(9999L);

              

        Project proj = new Project();

        proj.setName("Projecto ONE");

       

        Project proj2 = new Project();

        proj2.setName("Projecto X");

              

        emp.getProjects().add(proj);

        emp.getProjects().add(proj2);

       

        emp2.getProjects().add(proj2);

       

        proj.getEmployees().add(emp2);

        proj2.getEmployees().add(emp);

       

        em.getTransaction().begin();

        em.persist(emp);

        em.persist(emp2);

        em.persist(proj);          // Without PERSIST this is necesary

        em.persist(proj2);       // Withoiut PERSIST this is necesary

        em.getTransaction().commit();

        //em.flush();  

        em.close();

    }

If only is PERSISTED the employee with out CascadeType.PERSIST and not is PERSISTED the project the following error will throws:

[EL Warning]: java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: org.jamr.model.Project[ id=null ].

Exception in thread "main" javax.persistence.RollbackException: java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: org.jamr.model.Project[ id=null ].

                at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commit(EntityTransactionImpl.java:157)

                at com.jamr.example.Populate.populate(Populate.java:63)

                at com.jamr.example.Populate.main(Populate.java:25)

Caused by: java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: org.jamr.model.Project[ id=null ].

                at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.discoverUnregisteredNewObjects(RepeatableWriteUnitOfWork.java:310)

                at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.calculateChanges(UnitOfWorkImpl.java:723)

                at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitToDatabaseWithChangeSet(UnitOfWorkImpl.java:1516)

                at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.commitRootUnitOfWork(RepeatableWriteUnitOfWork.java:277)

                at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitAndResume(UnitOfWorkImpl.java:1169)

                at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commit(EntityTransactionImpl.java:132)

                ... 2 more

Otherwise with employee with CascadeType.PERSIST, is not necessary Persist de project. Is automatically persisted by his relationship marked with employee.