We Keep Coding

Composite key with one to many hibernate

I'm having a big problem trying to make this little program work
Here are my objects:
Class Country
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
public class Country implements Serializable {
private static final long serialVersionUID = 4947071545454L;
private String countryID;
private String countryName;
private Set<City> cities = new HashSet<City>();
public Country() {
}
public Country(String countryID, String countryName, Set<City> cities) {
this.countryID = countryID;
this.countryName = countryName;
this.cities = cities;
}
public static long getSerialVersionUID() {
return serialVersionUID;
}
public String getCountryID() {
return countryID;
}
public void setCountryID(String countryID) {
this.countryID = countryID;
}
public String getCountryName() {
return countryName;
}
public void setCountryName(String countryName) {
this.countryName = countryName;
}
public Set<City> getCities() {
return cities;
}
public void setCities(Set<City> cities) {
this.cities = cities;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Country country = (Country) o;
return countryID != null ? countryID.equals(country.countryID) : country.countryID == null;
}
#Override
public int hashCode() {
return countryID != null ? countryID.hashCode() : 0;
}
public boolean addCity(City c){
return cities.add(c);
}
public boolean removeCity(City c){
return cities.remove(c);
}
}
Class City
import java.io.Serializable;
public class City implements Serializable{
private static final long serialVersionUID = 49470713545454L;
private String cityName;
private Country id;
public City(String cityName, Country id) {
this.cityName = cityName;
this.id = id;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
public Country getId() {
return id;
}
public void setId(Country id) {
this.id = id;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
City city = (City) o;
if (cityName != null ? !cityName.equals(city.cityName) : city.cityName != null) return false;
return id != null ? id.equals(city.id) : city.id == null;
}
#Override
public int hashCode() {
int result = cityName != null ? cityName.hashCode() : 0;
result = 31 * result + (id != null ? id.hashCode() : 0);
return result;
}
}
An here are my xml archives:
country.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">
<hibernate-mapping>
<class name="com.samuel.hibernate.Country" table="country" catalog="training2">
<id name="country" type="string" column="countryID">
<generator class="assign"/>
</id>
<property name="countryName" type="string">
<column name="countryName" length="40" not-null="true" unique="true" />
</property>
<set name="city" inverse="true" cascade="all">
<key column="countryID" not-null="true" />
<one-to-many class="com.samuel.hibernate.City"/>
</set>
</class>
</hibernate-mapping>
city.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">
<hibernate-mapping>
<class name="com.samuel.hibernate.City" table="city" catalog="training2">
<composite-id name="id">
<key-many-to-one name="countryID" class="com.samuel.hibernate.Country"
column="countryID" />
<key-property name="cityName" column="cityName" type="string"/>
</composite-id>
</class>
</hibernate-mapping>
And here's my main class:
Main class
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import java.util.HashSet;
import java.util.Set;
public class Main {
public static void main(String[] args) {
System.out.println("..");
Configuration cfg=new Configuration();
cfg.configure("hibernate.cfg.xml");
// aquí es donde peta si falla conexión con Postgres
//creating seession factory object
System.out.println("Antes de crear sesion");
SessionFactory factory=cfg.buildSessionFactory();
System.out.println("Despues de crear sesion");
//creating session object
Session session=factory.openSession();
//creating transaction object
Transaction t=session.beginTransaction();
Set<City> citiesSpain = new HashSet<>();
Country spain = new Country("es","Spain",citiesSpain);
citiesSpain.add(new City("Barcelona",spain));
citiesSpain.add(new City("Madrid",spain));
session.persist(spain);
t.commit();
session.close();
factory.close();
System.out.println("END");
}
}
When I execute this code I get this error message:
Exception in thread "main" org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.component.PojoComponentTuplizer]
at org.hibernate.tuple.component.ComponentTuplizerFactory.constructTuplizer(ComponentTuplizerFactory.java:98)
at org.hibernate.tuple.component.ComponentTuplizerFactory.constructDefaultTuplizer(ComponentTuplizerFactory.java:119)
at org.hibernate.tuple.component.ComponentMetamodel.<init>(ComponentMetamodel.java:68)
at org.hibernate.mapping.Component.getType(Component.java:169)
at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:422)
at org.hibernate.mapping.RootClass.validate(RootClass.java:266)
at org.hibernate.boot.internal.MetadataImpl.validate(MetadataImpl.java:329)
at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:451)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:710)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:726)
at com.samuel.hibernate.Main.main(Main.java:22)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.hibernate.tuple.component.ComponentTuplizerFactory.constructTuplizer(ComponentTuplizerFactory.java:95)
... 10 more
Caused by: org.hibernate.PropertyNotFoundException: Could not locate getter method for property [com.samuel.hibernate.Country#cityName]
at org.hibernate.internal.util.ReflectHelper.findGetterMethod(ReflectHelper.java:418)
at org.hibernate.property.access.internal.PropertyAccessBasicImpl.<init>(PropertyAccessBasicImpl.java:41)
at org.hibernate.property.access.internal.PropertyAccessStrategyBasicImpl.buildPropertyAccess(PropertyAccessStrategyBasicImpl.java:27)
at org.hibernate.mapping.Property.getGetter(Property.java:308)
at org.hibernate.tuple.component.PojoComponentTuplizer.buildGetter(PojoComponentTuplizer.java:138)
at org.hibernate.tuple.component.AbstractComponentTuplizer.<init>(AbstractComponentTuplizer.java:47)
at org.hibernate.tuple.component.PojoComponentTuplizer.<init>(PojoComponentTuplizer.java:41)
... 15 more
I've tried looking online but I don't seem to find the solution. In my example, one country can have many cities, but one city can only have on country.

This error means that one or more setters/getters is missing. Make sure you define matching getters/setters for all your properties. And make sure that your properties annotated correctly.
I think that problem is that your cities set name is different in a class and in hbm.xml file. In your entity class you defined set as Set<City> cities and in your XML file you defined this property as name="city". So hibernate is searching setters and getters for city named property.
Make sure that variable and property name coincides. And add empty constructor in City.class.

Is it ok to use "<generator class="org.hibernate.id.enhanced.SequenceStyleGenerator">" instead of<generator class="sequence">

Hi Guys i was getting java.sql.SQLSyntaxErrorException: ORA-02289: sequence does not exist exception while trying to migrate from hibernate3 to hibernate5 i changed my mapping from "generator class="sequence"" to
"generator class="org.hibernate.id.enhanced.SequenceStyleGenerator"
now its working fine.please confirm it that its a legitimate solution.
Thanks
employee hbm
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="Employee" table="EMPLOYEE" schema="RPTUSER">
<id name="id" type="int" column="id">
<generator class="org.hibernate.id.enhanced.SequenceStyleGenerator">
<param name="optimizer">none</param>
<param name="sequence_name">testemployee_seq</param>
</generator>
</id>
<property name="firstName" column="first_name" type="string" not-null="true"/>
<property name="lastName" column="last_name" type="string" />
<property name="salary" column="salary" type="int" />
</class>
</hibernate-mapping>
Hibernate-cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<property name="hibernate.connection.url">
URL</property>
<property name="hibernate.connection.username">USERNAME</property>
<property name="hibernate.connection.password">PASSWORD</property><!-- 3des10qf7 -->
<property name="hibernate.connection.pool_size">1</property>
<property name="show_sql">true</property>
<property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
<property name="hibernate.hbm2ddl.auto">validate</property>
<mapping resource="Employee.hbm.xml" />
</session-factory>
</hibernate-configuration>
manage employee class
import java.util.Iterator;
import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
public class ManageEmployee {
private static SessionFactory factory;
public static void main(String[] args) {
try{
factory = new Configuration().configure().buildSessionFactory();
}catch (Throwable ex) {
System.err.println("Failed to create sessionFactory object." + ex);
throw new ExceptionInInitializerError(ex);
}
ManageEmployee ME = new ManageEmployee();
/* Add few employee records in database */
Integer empID1 = ME.addEmployee("Zara", "Ali", 1000);
Integer empID2 = ME.addEmployee("Daisy", "Das", 5000);
Integer empID3 = ME.addEmployee("John", "Paul", 10000);
/* List down all the employees */
ME.listEmployees();
/* Update employee's records */
ME.updateEmployee(empID1, 5000);
/* Delete an employee from the database */
ME.deleteEmployee(empID2);
/* List down new list of the employees */
ME.listEmployees();
}
/* Method to CREATE an employee in the database */
public Integer addEmployee(String fname, String lname, int salary){
Session session = factory.openSession();
Transaction tx = null;
Integer employeeID = null;
try{
tx = session.beginTransaction();
Employee employee = new Employee(fname, lname, salary);
employeeID = (Integer) session.save(employee);
tx.commit();
}catch (HibernateException e) {
if (tx!=null) tx.rollback();
e.printStackTrace();
}finally {
session.close();
}
return employeeID;
}
/* Method to READ all the employees */
public void listEmployees( ){
Session session = factory.openSession();
Transaction tx = null;
try{
tx = session.beginTransaction();
List employees = session.createQuery("FROM Employee").list();
for (Iterator iterator =
employees.iterator(); iterator.hasNext();){
Employee employee = (Employee) iterator.next();
System.out.print("First Name: " + employee.getFirstName());
System.out.print(" Last Name: " + employee.getLastName());
System.out.println(" Salary: " + employee.getSalary());
}
tx.commit();
}catch (HibernateException e) {
if (tx!=null) tx.rollback();
e.printStackTrace();
}finally {
session.close();
}
}
/* Method to UPDATE salary for an employee */
public void updateEmployee(Integer EmployeeID, int salary ){
Session session = factory.openSession();
Transaction tx = null;
try{
tx = session.beginTransaction();
Employee employee =
(Employee)session.get(Employee.class, EmployeeID);
employee.setSalary( salary );
session.update(employee);
tx.commit();
}catch (HibernateException e) {
if (tx!=null) tx.rollback();
e.printStackTrace();
}finally {
session.close();
}
}
/* Method to DELETE an employee from the records */
public void deleteEmployee(Integer EmployeeID){
Session session = factory.openSession();
Transaction tx = null;
try{
tx = session.beginTransaction();
Employee employee =
(Employee)session.get(Employee.class, EmployeeID);
session.delete(employee);
tx.commit();
}catch (HibernateException e) {
if (tx!=null) tx.rollback();
e.printStackTrace();
}finally {
session.close();
}
}
}
employee .java
public class Employee {
private int id;
private String firstName;
private String lastName;
private int salary;
public Employee() {}
public Employee(String fname, String lname, int salary) {
this.firstName = fname;
this.lastName = lname;
this.salary = salary;
}
public int getId() {
return id;
}
public void setId( int id ) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName( String first_name ) {
this.firstName = first_name;
}
public String getLastName() {
return lastName;
}
public void setLastName( String last_name ) {
this.lastName = last_name;
}
public int getSalary() {
return salary;
}
public void setSalary( int salary ) {
this.salary = salary;
}
}

First of all , I have to thank you for reminding me .
Use <param name="sequence_name">testemployee_seq</param>
Get to the point , maybe you should do like this .
<id name="id">
<generator class="sequence">
<param name="sequence_name">seq_admins</param>
</generator>
</id>

Session.get throwing exception instead of null

I run below program and expect that hibernate will throw ObjectNotFoundException for call to load and null for call to get. But I don't see book : null in the output.
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class LoadAndGetTest {
public static void main(String[] args) {
Configuration configuration = new Configuration().configure();
SessionFactory factory = configuration.buildSessionFactory();
Session session = factory.openSession();
try {
Book book = (Book) session.load(Book.class, "DOES_NOT_EXIST");
} catch(Exception exception) {
exception.printStackTrace();
}
Book book = (Book) session.get(Book.class, "DOES_NOT_EXIST");
System.out.println("book : "+ book);
}
}
Book.java
import java.util.Date;
import java.util.List;
public class Book {
private String isbn;
private String name;
private Publisher publisher;
private Date publishDate;
private int price;
private List chapters;
// Getters and Setters
public Book() {
}
public Book(String isbn, String name, Publisher publisher,
Date publishDate, int price, List chapters) {
super();
this.isbn = isbn;
this.name = name;
this.publisher = publisher;
this.publishDate = publishDate;
this.price = price;
this.chapters = chapters;
}
public String getIsbn() {
return isbn;
}
public String getName() {
return name;
}
public Publisher getPublisher() {
return publisher;
}
public Date getPublishDate() {
return publishDate;
}
public int getPrice() {
return price;
}
public List getChapters() {
return chapters;
}
public void setIsbn(String isbn) {
this.isbn = isbn;
}
public void setName(String name) {
this.name = name;
}
public void setPublisher(Publisher publisher) {
this.publisher = publisher;
}
public void setPublishDate(Date publishDate) {
this.publishDate = publishDate;
}
public void setPrice(int price) {
this.price = price;
}
public void setChapters(List chapters) {
this.chapters = chapters;
}
}
and book.hbm.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.chatar.hibernate.receipes.example.domain">
<class name="Book" table="BOOK">
<id name="isbn" type="string" column="ISBN" />
<property name="name" type="string" column="BOOK_NAME" />
<property name="publishDate" type="date" column="PUBLISH_DATE" />
<property name="price" type="int" column="PRICE" />
</class>
</hibernate-mapping>
And
hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.driver_class">
org.apache.derby.jdbc.EmbeddedDriver
</property>
<property name="connection.url">jdbc:derby://localhost:1527/BookShopDB</property>
<property name="connection.username">book</property>
<property name="connection.password">book</property>
<property name="dialect">org.hibernate.dialect.DerbyDialect</property>
<mapping resource="com/chatar/hibernate/receipes/example/domain/book.hbm.xml" />
</session-factory>
</hibernate-configuration>
And here's the exception
950 [main] INFO org.hibernate.event.def.DefaultLoadEventListener - Error performing load command
org.hibernate.ObjectNotFoundException: No row with the given identifier exists: [com.chatar.hibernate.receipes.example.domain.Book#DOES_NOT_EXIST]
at org.hibernate.impl.SessionFactoryImpl$2.handleEntityNotFound(SessionFactoryImpl.java:449)
at org.hibernate.event.def.DefaultLoadEventListener.returnNarrowedProxy(DefaultLoadEventListener.java:320)
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:277)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:152)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:1080)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:997)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:990)
at com.chatar.hibernate.receipes.example.LoadAndGetTest.main(LoadAndGetTest.java:21)
Exception in thread "main" org.hibernate.ObjectNotFoundException: No row with the given identifier exists: [com.chatar.hibernate.receipes.example.domain.Book#DOES_NOT_EXIST]
at org.hibernate.impl.SessionFactoryImpl$2.handleEntityNotFound(SessionFactoryImpl.java:449)
at org.hibernate.event.def.DefaultLoadEventListener.returnNarrowedProxy(DefaultLoadEventListener.java:320)
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:277)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:152)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:1080)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:997)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:990)
at com.chatar.hibernate.receipes.example.LoadAndGetTest.main(LoadAndGetTest.java:21)
However if I remove call to load then I can see book : null in the output.
LoadAndGetTest.java without call to load
public class LoadAndGetTest {
public static void main(String[] args) {
Configuration configuration = new Configuration().configure();
SessionFactory factory = configuration.buildSessionFactory();
Session session = factory.openSession();
Book book = (Book) session.get(Book.class, "DOES_NOT_EXIST");
System.out.println("book : "+ book);
}
}
output
book : null
Also when I called get twice before and after load I can see before one get printed but not the after one.
Here's the LoadAndGetTest again
public class LoadAndGetTest {
public static void main(String[] args) {
Configuration configuration = new Configuration().configure();
SessionFactory factory = configuration.buildSessionFactory();
Session session = factory.openSession();
Book book1 = (Book) session.get(Book.class, "DOES_NOT_EXIST");
System.out.println("book : "+ book1);
try {
Book book = (Book) session.load(Book.class, "DOES_NOT_EXIST");
} catch(Exception exception) {
exception.printStackTrace();
}
Book book = (Book) session.get(Book.class, "DOES_NOT_EXIST");
System.out.println("book : "+ book);
}
}
Output
book : null
1292 [main] INFO org.hibernate.event.def.DefaultLoadEventListener - Error performing load command
org.hibernate.ObjectNotFoundException: No row with the given identifier exists: [com.chatar.hibernate.receipes.example.domain.Book#DOES_NOT_EXIST]
at org.hibernate.impl.SessionFactoryImpl$2.handleEntityNotFound(SessionFactoryImpl.java:449)
at org.hibernate.event.def.DefaultLoadEventListener.returnNarrowedProxy(DefaultLoadEventListener.java:320)
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:277)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:152)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:1080)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:997)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:990)
at com.chatar.hibernate.receipes.example.LoadAndGetTest.main(LoadAndGetTest.java:24)
Exception in thread "main" org.hibernate.ObjectNotFoundException: No row with the given identifier exists: [com.chatar.hibernate.receipes.example.domain.Book#DOES_NOT_EXIST]
at org.hibernate.impl.SessionFactoryImpl$2.handleEntityNotFound(SessionFactoryImpl.java:449)
at org.hibernate.event.def.DefaultLoadEventListener.returnNarrowedProxy(DefaultLoadEventListener.java:320)
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:277)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:152)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:1080)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:997)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:990)
at com.chatar.hibernate.receipes.example.LoadAndGetTest.main(LoadAndGetTest.java:24)

Ok. I was able to figure out after checking source code and following stack trace:
It seems if you call get after a calling load, Hibernate uses proxy object. Here's the sequence of calls,
1. Book book = (Book) session.get(Book.class, "DOES_NOT_EXIST");
2. SessionImpl.get
public Object get(Class entityClass, Serializable id) throws HibernateException {
return get( entityClass.getName(), id );
}
3. fireLoad(event, LoadEventListener.GET);
4. DefaultLoadEventListener.onLoad
//return a proxy if appropriate
if ( event.getLockMode() == LockMode.NONE ) {
event.setResult( proxyOrLoad(event, persister, keyToLoad, loadType) );
}
5. DefaultLoadEventListener.proxyOrLoad
if ( proxy != null ) {
return returnNarrowedProxy( event, persister, keyToLoad, options, persistenceContext, proxy );
}
6. DefaultLoadEventListener.returnNarrowedProxy
if ( !options.isAllowProxyCreation() ) {
impl = load( event, persister, keyToLoad, options );
if ( impl == null ) {
event.getSession().getFactory().getEntityNotFoundDelegate().handleEntityNotFound( persister.getEntityName(), keyToLoad.getIdentifier());
}
}
7. SessionFactoryImpl.handleEntityNotFound
// EntityNotFoundDelegate
EntityNotFoundDelegate entityNotFoundDelegate = cfg.getEntityNotFoundDelegate();
if ( entityNotFoundDelegate == null ) {
entityNotFoundDelegate = new EntityNotFoundDelegate() {
public void handleEntityNotFound(String entityName, Serializable id) {
throw new ObjectNotFoundException( id, entityName );
}
public boolean isEntityNotFoundException(RuntimeException exception) {
return ObjectNotFoundException.class.isInstance( exception );
}
};
}

Hibernate Mapped Composite Key ManyToMany results in ClassCastException

I am struggling with a hibernate problem since hours and can not find any help on any website. I've read dozens of tutorials, tried everything but I always end up with a class cast exception or compilation errors.
My schema in this particular part of the database (mysql innodb) are Plane and Steward. They share a Many2Many relationship.
Using Hibernate Code Generation and Hibernate Tools I generated all POJO classes and the mapping files (including a FlightHasStewardId and FlightHasSteward -> Mapped Composite ID).
I now want to read out all stewards on flight 100!
Notice: Reading other entities works, just M2M reading results in ClassCastEX.
Here my input:
Mapping of FlightHasSteward:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- Generated Jan 1, 2014 1:52:14 PM by Hibernate Tools 4.0.0 -->
<hibernate-mapping>
<class name="FlightHasSteward" table="Flight_has_Steward" catalog="project3flight">
<composite-id name="id" class="FlightHasStewardId">
<key-property name="flightIdflight" type="int">
<column name="Flight_idflight" />
</key-property>
<key-property name="stewardIdsteward" type="int">
<column name="Steward_idsteward" />
</key-property>
</composite-id>
</class>
</hibernate-mapping>
FlightHasSteward.java:
// default package
// Generated Jan 1, 2014 1:52:14 PM by Hibernate Tools 4.0.0
/**
* FlightHasSteward generated by hbm2java
*/
public class FlightHasSteward implements java.io.Serializable {
private FlightHasStewardId id;
public FlightHasSteward() {
}
public FlightHasSteward(FlightHasStewardId id) {
this.id = id;
}
public FlightHasStewardId getId() {
return this.id;
}
public void setId(FlightHasStewardId id) {
this.id = id;
}
}
FlightHasStewardId.java:
// default package
// Generated Jan 1, 2014 1:52:14 PM by Hibernate Tools 4.0.0
/**
* FlightHasStewardId generated by hbm2java
*/
public class FlightHasStewardId implements java.io.Serializable {
private int flightIdflight;
private int stewardIdsteward;
public FlightHasStewardId() {
}
public FlightHasStewardId(int flightIdflight, int stewardIdsteward) {
this.flightIdflight = flightIdflight;
this.stewardIdsteward = stewardIdsteward;
}
public int getFlightIdflight() {
return this.flightIdflight;
}
public void setFlightIdflight(int flightIdflight) {
this.flightIdflight = flightIdflight;
}
public int getStewardIdsteward() {
return this.stewardIdsteward;
}
public void setStewardIdsteward(int stewardIdsteward) {
this.stewardIdsteward = stewardIdsteward;
}
public boolean equals(Object other) {
if ((this == other))
return true;
if ((other == null))
return false;
if (!(other instanceof FlightHasStewardId))
return false;
FlightHasStewardId castOther = (FlightHasStewardId) other;
return (this.getFlightIdflight() == castOther.getFlightIdflight())
&& (this.getStewardIdsteward() == castOther.getStewardIdsteward());
}
public int hashCode() {
int result = 17;
result = 37 * result + this.getFlightIdflight();
result = 37 * result + this.getStewardIdsteward();
return result;
}
}
Reader.java (my class to read):
/* Method to READ all the stewards on specific flight */
public void getStewards(int flightid) {
Session session = factory.openSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
// Query query = session
// .createQuery(" FROM FlightHasSteward as FHS LEFT JOIN FHS.Flight AS F ON F.idFlight = FHS.Flight_idFlight RIGHT JOIN FHS.Steward AS S ON S.idSteward = FHS.Steward_idSteward where FHS.Flight_idFlight = :code");
Query query = session.createQuery(" FROM FlightHasSteward where Flight_idFlight = :code");
query.setParameter("code", flightid);
List<FlightHasStewardId> result = query.list();
final List<FlightHasStewardId> res = (List<FlightHasStewardId>) query.list();
for (final FlightHasStewardId hall_calendar : res) {
System.out.println(hall_calendar.getStewardIdsteward());
}
tx.commit();
} catch (HibernateException e) {
if (tx != null)
tx.rollback();
e.printStackTrace();
} finally {
session.close();
}
}
And the disturbing output:
Exception in thread "main" java.lang.ClassCastException: FlightHasSteward cannot be cast to FlightHasStewardId
at Reader.getStewards(Reader.java:97)
at Manager.main(Manager.java:24)
I would appreciate any help with this case, thank you all in advance.

You're selecting from FlightHasSteward so the resultant List will contain those types rather than FlightHasStewardId
Query query = session.createQuery(" FROM FlightHasSteward where Flight_idFlight = :code");
query.setParameter("code", flightid);
List<FlightHasSteward> result = query.list();
final List<FlightHasSteward> res = (List<FlightHasSteward>) query.list();
for (final FlightHasSteward steward : res) {
System.out.println(steward.getId().getStewardIdsteward());
}

hibernate doesn't see a setter

I am new to hibernate and I have stupid problem. My files:
hibernate.cfg.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration SYSTEM "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.dialect">
org.hibernate.dialect.PostgreSQLDialect
</property>
<property name="hibernate.connection.driver_class">
org.postgresql.Driver
</property>
<!-- Assume test is the database name -->
<property name="hibernate.connection.url">
jdbc:postgresql://localhost/booktown
</property>
<property name="hibernate.connection.username">
mirek
</property>
<mapping resource="Books.hbm.xml"/>
</session-factory>
</hibernate-configuration>
books.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="Books" table="books">
<meta attribute="Książki w booktown">
This class contains the employee detail.
</meta>
<id name="id" type="int" column="id">
<generator class="native"/>
</id>
<property name="title" column="title" type="string"/>
<property name="author_id" column="author_id" type="int"/>
<property name="subject_id" column="subject_id" type="int"/>
</class>
</hibernate-mapping>
Books.java
public class Books
{
private int id;
private String title;
private int author_id;
private int subject_id;
public Books(String title, int author_id, int subject_id)
{
this.title = title;
this.author_id = author_id;
this.subject_id = subject_id;
}
public void setId(int id)
{
this.id = id;
}
public void setTitle(String title)
{
this.title = title;
}
public void setAuthorId(int author_id)
{
this.author_id = author_id;
}
public void setSubjectId(int subject_id)
{
this.subject_id = subject_id;
}
public int getId()
{
return id;
}
public String getTitle()
{
return title;
}
public int getAuthorId()
{
return author_id;
}
public int getSubjectId()
{
return subject_id;
}
}
and Booktown.java
import java.util.Iterator;
import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
public class Booktown
{
private static SessionFactory factory;
private static ServiceRegistry serviceRegistry;
public static void main(String[] args)
{
try
{
//private static SessionFactory configureSessionFactory() throws HibernateException {
Configuration configuration = new Configuration();
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
factory = configuration.buildSessionFactory(serviceRegistry);
//return factory;
//factory = new Configuration().configure().buildSessionFactory();
}
catch (Throwable ex)
{
System.err.println("Failed to create sessionFactory object." + ex.toString());
throw new ExceptionInInitializerError(ex);
}
Booktown BT = new Booktown();
/* Add few employee records in database */
Integer bID1 = BT.addBook(10, "Jakiś napis", 10, 30);
Integer bID2 = BT.addBook(20, "Jakiś inny napis", 10, 50);
//Integer bID3 = BT.addBook(30, "John", 10000, 14);
/* List down all the employees */
BT.listBooks();
/* Update employee's records */
BT.updateBook(bID1, 5000);
/* Delete an employee from the database */
BT.deleteBook(bID2);
/* List down new list of the employees */
BT.listBooks();
}
/* Method to CREATE a book in the database */
public Integer addBook(int bid, String fname, int lname, int salary)
{
Session session = factory.openSession();
Transaction tx = null;
Integer bID = null;
try
{
tx = session.beginTransaction();
Books book = new Books(fname, lname, salary);
bid = (Integer) session.save(book);
tx.commit();
}
catch (HibernateException e)
{
if (tx != null)
tx.rollback();
e.printStackTrace();
}
finally
{
session.close();
}
return bID;
}
/* Method to READ all the books */
public void listBooks()
{
Session session = factory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
List<Books> books = session.createQuery("FROM books").list();
for (Iterator<Books> iterator = books.iterator(); iterator.hasNext();)
{
Books book = (Books) iterator.next();
System.out.print("First Name: " + book.getTitle());
System.out.print(" Last Name: " + book.getAuthorId());
System.out.println(" Salary: " + book.getSubjectId());
}
tx.commit();
}
catch (HibernateException e)
{
if (tx != null)
tx.rollback();
e.printStackTrace();
}
finally
{
session.close();
}
}
/* Method to UPDATE author for a book */
public void updateBook(Integer bID, int auth)
{
Session session = factory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
Books book = (Books) session.get(Books.class, bID);
book.setAuthorId(auth);
session.update(book);
tx.commit();
}
catch (HibernateException e)
{
if (tx != null)
tx.rollback();
e.printStackTrace();
}
finally
{
session.close();
}
}
/* Method to DELETE a book from the records */
public void deleteBook(Integer bID)
{
Session session = factory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
Books book = (Books) session.get(Books.class, bID);
session.delete(book);
tx.commit();
}
catch (HibernateException e)
{
if (tx != null)
tx.rollback();
e.printStackTrace();
}
finally
{
session.close();
}
}
}
Code is compiling but at run I get:
> paź 15, 2013 8:44:38 PM org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory <init>
INFO: HHH000397: Using ASTQueryTranslatorFactory
Failed to create sessionFactory object.org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
Exception in thread "main" java.lang.ExceptionInInitializerError
at Booktown.main(Booktown.java:34)
Caused by: org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
at org.hibernate.persister.internal.PersisterFactoryImpl.create(PersisterFactoryImpl.java:185)
at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:135)
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:385)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1790)
at Booktown.main(Booktown.java:25)
Caused by: org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer]
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:138)
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:188)
at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:341) at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:507)
at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:146)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at org.hibernate.persister.internal.PersisterFactoryImpl.create(PersisterFactoryImpl.java:163)
... 4 more
Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:135)
... 13 more
Caused by: org.hibernate.PropertyNotFoundException: Could not find a getter for author_id in class Books
at org.hibernate.property.BasicPropertyAccessor.createGetter(BasicPropertyAccessor.java:316)
at org.hibernate.property.BasicPropertyAccessor.getGetter(BasicPropertyAccessor.java:310)
at org.hibernate.mapping.Property.getGetter(Property.java:321)
at org.hibernate.tuple.entity.PojoEntityTuplizer.buildPropertyGetter(PojoEntityTuplizer.java:444)
at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:200)
at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:82)
... 18 more
I found similar problem there was no setter. In my case system says that there is no getter for author_id but it is at line 45 in Books.java.
Could sb tells me what is wrong? Maybe there is an other cause which I don't see...

public int getAuthorId()
{
return author_id;
}
should be (observe, author_id)
public int getAuthor_id()
{
return author_id;
}
OR update XML as #Boris the spider commented.

As far as I know Hibernate requires a no-arg constructor which your Books class does seem to have. So even if you get the save part working I think your code will fail when you attempt to load.
Thus, create a constructor:
public Books(){
}
Why does Hibernate require no argument constructor?
Also, as pointed out previously ditch the XML and use JPA annotations. In line with standard Java conventions rename Books to Book and remove the _ from your variable names.
Alan

I had once this problem and I fix it like that:
You should Generate Constructor, Getters and Setters in NetBeans IDE ( I'm working with IDE is netbeans) so you have to press shortcut ALT+Insert (CTLRL+I on Mac). After invoking the shortcut, all possible generators are offered.