relationship whith hibernate

Question

I am using Eclipse, Xammp (tomcat and MySQL DB) and Hibernate.

i will create something like relationshipt.

my Entity class:

package Dto;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
import javax.persistence.JoinColumn;

@Entity
@Table(name="EMPLOYEE")
public class Employee {

    @Id
    @Column(name="EMPLOYEE_ID")
    @GeneratedValue
    private Long employeeId;

    @Column(name="FIRSTNAME")
    private String firstname;

    @Column(name="LASTNAME")
    private String lastname;


    @ManyToMany(cascade={CascadeType.ALL})
    @JoinTable(name="EMPLOYEE_COLLEAGUE",
        joinColumns={@JoinColumn(name="EMPLOYEE_ID")},
        inverseJoinColumns={@JoinColumn(name="COLLEAGUE_ID")})
    private Set<Employee> colleagues = new HashSet<Employee>();

    @ManyToMany(mappedBy="colleagues")
    private Set<Employee> teammates = new HashSet<Employee>();

    public Employee() {
    }

    public Employee(String firstname, String lastname) {
        this.firstname = firstname;
        this.lastname = lastname;
    }

    //Getter and Setter...
         ...
}

My hbm.xml:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 23.05.2016 15:44:11 by Hibernate Tools 3.5.0.Final -->
<hibernate-mapping>
    <class name="Dto.Employee" table="EMPLOYEE">
        <id name="employeeId" type="java.lang.Long">
            <column name="EMPLOYEEID" />
            <generator class="native" />
        </id>
        <property name="firstname" type="java.lang.String">
            <column name="FIRSTNAME" />
        </property>
        <property name="lastname" type="java.lang.String">
            <column name="LASTNAME" />
        </property>
        <set name="colleagues" table="EMPLOYEE" inverse="false" lazy="true">
            <key>
                <column name="EMPLOYEEID" />
            </key>
            <one-to-many class="Dto.Employee" />
        </set>
        <set name="teammates" table="EMPLOYEE" inverse="false" lazy="true">
            <key>
                <column name="EMPLOYEEID" />
            </key>
            <one-to-many class="Dto.Employee" />
        </set>
    </class>
</hibernate-mapping>

My hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/Hibernate</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="hbm2ddl.auto">create-drop</property>

        <mapping resource="Dto/Employee.hbm.xml" />
    </session-factory>
</hibernate-configuration>

My Main Class:

Configuration configuration = new Configuration();
         configuration.configure("resources/hibernate.cfg.xml");

         SessionFactory sessionFactory = configuration.buildSessionFactory();

         Session session = sessionFactory.openSession();

         session.beginTransaction();



            Employee employee1 = new Employee("Sergey", "Brin");
            Employee employee2 = new Employee("Larry", "Page");
            Employee employee3 = new Employee("Marrisa", "Mayer");
            Employee employee4 = new Employee("Matt", "Cutts");

            employee1.getColleagues().add(employee3);
//          employee1.getColleagues().add(employee4);


            session.save(employee1);
            session.save(employee2);
            session.save(employee3);
            session.save(employee4);

            session.getTransaction().commit();
            session.close();

My Error:

log4j:WARN No appenders could be found for logger (org.jboss.logging).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.hibernate.exception.ConstraintViolationException: could not execute statement
    at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:59)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:207)
    at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:45)
    at org.hibernate.persister.collection.AbstractCollectionPersister.recreate(AbstractCollectionPersister.java:1313)
    at org.hibernate.persister.collection.OneToManyPersister.recreate(OneToManyPersister.java:170)
    at org.hibernate.action.internal.CollectionRecreateAction.execute(CollectionRecreateAction.java:50)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:560)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:434)
    at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:337)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39)
    at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1295)
    at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:468)
    at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3135)
    at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2352)
    at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:485)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:147)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$100(JdbcResourceLocalTransactionCoordinatorImpl.java:38)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:231)
    at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:65)
    at Dao.UserDao.testFriend(UserDao.java:208)
    at Test.Main.main(Main.java:40)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '1' for key 'PRIMARY'
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
    at com.mysql.jdbc.Util.getInstance(Util.java:387)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:932)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3878)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3814)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2478)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2625)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2551)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1861)
    at com.mysql.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2073)
    at com.mysql.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2009)
    at com.mysql.jdbc.PreparedStatement.executeLargeUpdate(PreparedStatement.java:5094)
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1994)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:204)
    ... 19 more

if i dosn't use employee1.getColleagues().add(employee3); in my Mainclass. then all is working and Hibernate save all the EMPLOYEE in the MySQL Database. just the employee1.getColleagues().add(employee3);´ dosn't work and i don't know why. I think it's because thehbm.xml`. But i don't know, what i have to change

in my Database is just the Table EMPLOYEE.

You are using annotations AND xml configuration. You should either use one or the other, never both — lance-java, May 23 '16 at 14:35

K.Nicholas · Answer 1 · 2016-05-23T17:30:13.937

0

It looks like employee3 is saved through the cascade={CascadeType.ALL}) annotation when employee3 is added to the colleagues list. Then it is saved again when you call session.save(employee3);, and it has the same ID which invalidates the primary key constraint. So, either save it first, before adding it to the colleagues list, or don't save it again after adding it to the list. Something like:

employee3 = session.save(employee3);
employee1.getColleagues().add(employee3);

edited May 23 '16 at 17:30

answered May 23 '16 at 14:34

K.Nicholas

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i changed the code and put the id's manualy. And it dosn't work, too. – Niklas Honorwood May 23 '16 at 14:51
and if i save first and then add to Colleagues. it's the same error, too – Niklas Honorwood May 23 '16 at 14:55
It's strange that you have both annotations and hibernate.xml. Are you sure you can do that? [In Hibernate: is it possible to mix Annotations and XML configuration for an Entity?](http://stackoverflow.com/questions/8643166/in-hibernate-is-it-possible-to-mix-annotations-and-xml-configuration-for-an-ent) – K.Nicholas May 23 '16 at 14:56
if i dosn't add a `Colleagues`, this mix is working. – Niklas Honorwood May 23 '16 at 15:04
Are you re-assigning employee3 after you save it? Maybe it needs a saveOrUpdate. The error message is pretty self explanatory. – K.Nicholas May 23 '16 at 17:32

relationship whith hibernate

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