@OneToMany Example In JPA with transaction type JTA

[Bennet Xavier]

Hi All,

I need a sample code for @OneToMany relationship.

i have a entity as follows:

Employee.java

@Entity
public class Employee implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.TABLE)
private Long id = -1l;
private String name;
@OneToMany(mappedBy="employee", cascade= CascadeType.ALL)
private List<PhoneNumber> phoneNumber;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<PhoneNumber> getPhoneNumber() {
return phoneNumber;
}
public void setPhoneNumber(List<PhoneNumber> phoneNumber) {
this.phoneNumber = phoneNumber;
}
}

PhoneNumber.java

@Entity
public class PhoneNumber implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column(name = "SAMPLE_NUMBER")
private String number;
@ManyToOne(cascade= CascadeType.ALL)
@JoinColumn(name = "EMPLOYEE_ID", insertable = false, updatable = false, nullable = false)
private Employee employee;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
public Employee getEmployee() {
return employee;
}
public void setEmployee(Employee employee) {
this.employee = employee;
}
}

bean is getting deployed successfully in jboss5.1.0.GA without any problem and table is getting created.

I have EmployeeFacade Stateless Session Bean as follows:

@Stateless
public class EmployeeFacade extends AbstractFacade<Employee> implements EmployeeFacadeLocal, EmployeeFacadeRemote {
@PersistenceContext(unitName = "titan")
private EntityManager em;
protected EntityManager getEntityManager() {
return em;
}
public EmployeeFacade() {
super(Employee.class);
}
}

PhoneNumberFacade Stateless Session Bean as follows:

@Stateless
public class PhoneNumberFacade extends AbstractFacade<PhoneNumber> implements PhoneNumberFacadeLocal , PhoneNumberFacadeRemote{
@PersistenceContext(unitName = "titan")
private EntityManager em;
protected EntityManager getEntityManager() {
return em;
}
public PhoneNumberFacade() {
super(PhoneNumber.class);
}
}

both EmployeeFacade, PhoneNumberFacade inherits :

public abstract class AbstractFacade<T> {
private Class<T> entityClass;
public AbstractFacade(Class<T> entityClass) {
this.entityClass = entityClass;
}
protected abstract EntityManager getEntityManager();
public T create(T entity) {
getEntityManager().persist(entity);
return entity;
}
public void edit(T entity) {
getEntityManager().merge(entity);
}
public void remove(T entity) {
getEntityManager().remove(getEntityManager().merge(entity));
}
public T find(Object id) {
return getEntityManager().find(entityClass, id);
}
public List<T> findAll() {
return getEntityManager().createQuery("select object(o) from " + entityClass.getSimpleName() + " as o").getResultList();
}
public List<T> findRange(int[] range) {
javax.persistence.Query q = getEntityManager().createQuery("select object(o) from " + entityClass.getSimpleName() + " as o");
q.setMaxResults(range[1] - range[0]);
q.setFirstResult(range[0]);
return q.getResultList();
}
public int count() {
return ((Long) getEntityManager().createQuery("select count(o) from " + entityClass.getSimpleName() + " as o").getSingleResult()).intValue();
}
}

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0" >
<persistence-unit name="titan">
<jta-data-source>java:/OracleDS</jta-data-source>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
</properties>
</persistence-unit>
</persistence>

Client :

public class Client
{
public static void main(String [] args)
{
try
{
Context jndiContext = getInitialContext();
Object ref = jndiContext.lookup("EmployeeFacade/remote");
EmployeeFacadeRemote dao = (EmployeeFacadeRemote)ref;
Object ref1 = jndiContext.lookup("PhoneNumberFacade/remote");
PhoneNumberFacadeRemote phoneNumberFacadeDao = (PhoneNumberFacadeRemote)ref1;
Employee employee = new Employee();
employee.setName("Master Suite");
employee.setRollNumner("123456");
employee.setColour("BLACK");
employee.setHeight(123);
employee.setWeight(1234);
PhoneNumber phoneNumber = null;
phoneNumber = new PhoneNumber();
phoneNumber.setAreaCode("044");
phoneNumber.setCountryCode("+91");
phoneNumber.setNumber("7036303012");
phoneNumber.setEmployee(employee);
phoneNumberFacadeDao.create(phoneNumber);
}
catch (javax.naming.NamingException ne)
{
ne.printStackTrace();
}
}
public static Context getInitialContext()
throws javax.naming.NamingException
{
return new javax.naming.InitialContext();
}
}

ERROR [AbstractFlushingEventListener] Could not synchronize database state with session

and

Caused by: java.sql.BatchUpdateException: ORA-01400: cannot insert NULL into ("EXAMPLE"."PHONENUMBER"."EMPLOYEE_ID")

at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:343)
at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:10656)
at org.jboss.resource.adapter.jdbc.WrappedStatement.executeBatch(WrappedStatement.java:774)
at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
... 39 more


Please help me to resolve this problem.

Thanks,
Bennet Xavier X.

[Bin Smith]

Hello!

In my copybook where I am writing interesting notes it is written:
To be an entity class must follow these rules:
1. class must be annotated with @Entity
2. class must contain primary key annotated by @Id
3. class must contain public or protected no-argument constructor
4. class annotated by @Entity must be top-level, class without implementing or extending something
5. entity class must be not final, must not contain final variable or methods.
Also it is written:
Persistence provider maps entity to table thanks to annotation.
Do you have persistence provider configured in persistence.xml. If not then look at my persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="OlympicsPU" transaction-type="JTA">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<jta-data-source>jdbc/olympicsDS</jta-data-source>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/olympics?zeroDateTimeBehavior=convertToNull"/>
<property name="javax.persistence.jdbc.password" value="123456"/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="javax.persistence.jdbc.user" value="root"/>
</properties>
</persistence-unit>
</persistence>

[Ranganathan Kaliyur Mannar]

Hi Bennet,
In your case Employee is the parent and PhoneNumber is the child. So, the usual way to do is to create the parent object and add the child objects via the list and then persist the parent object (rather than the child object).
In your case, you should persist the Employee object via the EmployeeFacade (and the PhoneNumber object(s) should be added to the List<PhoneNumber>).