Guys,

I am new to hibernate.I want to know how to map a foreign key in hibernate configuration.

I have two tables.

Table: Employee

column: SerialNo (INTEGER) (PK)

column: Name (VARCHAR)

column: DepartmentNo(INTEGER) (FK)

Table: Department


column: DepartmentNo(INTEGER) (PK)

column: DepartmentName(VARCHAR)

Classes I use are.

Employee.java

public class Employee {

int serialno;
String name;
int Deptno;
public int getSerialno() {
return serialno;
}
public void setSerialno(int serialno) {
this.serialno = serialno;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}


Department.java

public class Department {

int deptno;
String DeptName;
public int getDeptno() {
return deptno;
}
public void setDeptno(int deptno) {
this.deptno = deptno;
}
public String getDeptName() {
return deptName;
}
public void setDeptName(String deptName) {
this.deptName = deptName;
}

}


Can Some one please help me how to map the foreign key in the .hbm.xml file?

Hope to hear from one.

Thanks.

I guess the mapping for the person class should be:

Hi,
Check documentation section: 5.1.10. many-to-one

In your employee mapping you will have to declare something similar to:

ok I tried it.I am getting errors though.I am pasting the code,xml files and the error from eclipse console below.Please have a look and tell me where I went wrong.
Thanks in advance


Employee.java
public class Employee {



int Deptno;
int serialno;
String name;

public int getSerialno() {
return serialno;
}
public void setSerialno(int serialno) {
this.serialno = serialno;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getDeptno() {
return Deptno;
}
public void setDeptno(int deptno) {
Deptno = deptno;
}



}


Employee.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="Employee" table="Employee">
<id name="serialno" type="int" column="serialno" >
<generator class="assigned"/>
</id>
<many-to-one name="Deptno" class="Department" column="Deptno"/>

<property name="name">
<column name="name" />
</property>

</class>
</hibernate-mapping>



Department.java
public class Department {


int Deptno;
String DeptName;

public String getDeptName() {
return DeptName;
}
public void setDeptName(String deptName) {
DeptName = deptName;
}
public int getDeptno() {
return Deptno;
}
public void setDeptno(int deptno) {
Deptno = deptno;
}

}


Department.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="Department" table="Department">
<id name="Deptno" type="int" column="Deptno" >
<generator class="assigned"/>
</id>

<one-to-one name="Deptno" class="Employee" property-ref="Deptno"/>
<property name="DeptName">
<column name="DeptName" />
</property>

</class>
</hibernate-mapping>



Test.java(Test program that I use to call all the functions)


import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
public class test {
public static void main(String[] args) {
Session session = null;

try{

SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
session =sessionFactory.openSession();
Department department = new Department();
Employee employee = new Employee();

department.setDeptName("IT");
department.setDeptno(5);

employee.setName("seby");
employee.setSerialno(4);
Transaction tx=session.beginTransaction();
session.save(department);
session.save(employee);
tx.commit();

System.out.println("INSERTING RECORDS TO DB" );
}catch(Exception e){
System.out.println(e.getMessage());
}finally{

session.flush();
session.close();

}

}
}


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">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost/test</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password"></property>
<property name="hibernate.connection.pool_size">10</property>
<property name="show_sql">true</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<!-- Mapping files -->

<mapping resource="Department.hbm.xml"/>
<mapping resource="Employee.hbm.xml"/>

</session-factory>
</hibernate-configuration>


Eclipse Console
05:15:32,531 INFO Environment:464 - Hibernate 3.0.5
05:15:32,531 INFO Environment:477 - hibernate.properties not found
05:15:32,531 INFO Environment:510 - using CGLIB reflection optimizer
05:15:32,546 INFO Environment:540 - using JDK 1.4 java.sql.Timestamp handling
05:15:32,625 INFO Configuration:1110 - configuring from resource: /hibernate.cfg.xml
05:15:32,625 INFO Configuration:1081 - Configuration resource: /hibernate.cfg.xml
05:15:33,093 INFO Configuration:444 - Mapping resource: Department.hbm.xml
05:15:33,234 INFO HbmBinder:260 - Mapping class: Department -> Department
05:15:33,265 INFO Configuration:444 - Mapping resource: Employee.hbm.xml
05:15:33,296 INFO HbmBinder:260 - Mapping class: Employee -> Employee
05:15:33,375 INFO Configuration:1222 - Configured SessionFactory: null
05:15:33,375 INFO Configuration:875 - processing extends queue
05:15:33,375 INFO Configuration:879 - processing collection mappings
05:15:33,375 INFO Configuration:888 - processing association property references
05:15:33,375 INFO Configuration:917 - processing foreign key constraints
05:15:33,390 INFO DriverManagerConnectionProvider:41 - Using Hibernate built-in connection pool (not for production use!)
05:15:33,390 INFO DriverManagerConnectionProvider:42 - Hibernate connection pool size: 10
05:15:33,390 INFO DriverManagerConnectionProvider:45 - autocommit mode: false
05:15:33,406 INFO DriverManagerConnectionProvider:80 - using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost/test
05:15:33,406 INFO DriverManagerConnectionProvider:86 - connection properties: {user=root, password=****}
05:15:33,828 INFO SettingsFactory:77 - RDBMS: MySQL, version: 5.0.45-community-nt
05:15:33,828 INFO SettingsFactory:78 - JDBC driver: MySQL-AB JDBC Driver, version: mysql-connector-java-5.1.5 ( Revision: ${svn.Revision} )
05:15:33,843 INFO Dialect:92 - Using dialect: org.hibernate.dialect.MySQLDialect
05:15:33,859 INFO TransactionFactoryFactory:31 - Using default transaction strategy (direct JDBC transactions)
05:15:33,859 INFO TransactionManagerLookupFactory:33 - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended)
05:15:33,859 INFO SettingsFactory:125 - Automatic flush during beforeCompletion(): disabled
05:15:33,859 INFO SettingsFactory:129 - Automatic session close at end of transaction: disabled
05:15:33,859 INFO SettingsFactory:136 - JDBC batch size: 15
05:15:33,859 INFO SettingsFactory:139 - JDBC batch updates for versioned data: disabled
05:15:33,859 INFO SettingsFactory:144 - Scrollable result sets: enabled
05:15:33,859 INFO SettingsFactory:152 - JDBC3 getGeneratedKeys(): enabled
05:15:33,859 INFO SettingsFactory:160 - Connection release mode: null
05:15:33,859 INFO SettingsFactory:184 - Maximum outer join fetch depth: 2
05:15:33,859 INFO SettingsFactory:187 - Default batch fetch size: 1
05:15:33,859 INFO SettingsFactory:191 - Generate SQL with comments: disabled
05:15:33,859 INFO SettingsFactory:195 - Order SQL updates by primary key: disabled
05:15:33,859 INFO SettingsFactory:334 - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory
05:15:33,859 INFO ASTQueryTranslatorFactory:21 - Using ASTQueryTranslatorFactory
05:15:33,859 INFO SettingsFactory:203 - Query language substitutions: {}
05:15:33,859 INFO SettingsFactory:209 - Second-level cache: enabled
05:15:33,859 INFO SettingsFactory:213 - Query cache: disabled
05:15:33,859 INFO SettingsFactory:321 - Cache provider: org.hibernate.cache.EhCacheProvider
05:15:33,875 INFO SettingsFactory:228 - Optimize cache for minimal puts: disabled
05:15:33,875 INFO SettingsFactory:237 - Structured second-level cache entries: disabled
05:15:33,875 INFO SettingsFactory:257 - Echoing all SQL to stdout
05:15:33,875 INFO SettingsFactory:261 - Statistics: disabled
05:15:33,875 INFO SettingsFactory:265 - Deleted entity synthetic identifier rollback: disabled
05:15:33,890 INFO SettingsFactory:279 - Default entity-mode: pojo
05:15:34,046 INFO SessionFactoryImpl:152 - building session factory
05:15:34,046 DEBUG CacheManager:191 - Creating new CacheManager with default config
05:15:34,046 DEBUG CacheManager:164 - Configuring ehcache from classpath.
05:15:34,062 WARN Configurator:126 - No configuration found. Configuring ehcache from ehcache-failsafe.xml found in the classpath: jar:file:/C:/Documents%20and%20Settings/anoop/Desktop/hibernate-3.0.5/hibernate-3.0/lib/ehcache-1.1.jar!/ehcache-failsafe.xml
05:15:34,078 DEBUG Configuration$DiskStore:185 - Disk Store Path: C:\DOCUME~1\anoop\LOCALS~1\Temp\
05:15:34,453 INFO SessionFactoryObjectFactory:82 - Not binding factory to JNDI, no JNDI name configured
05:15:34,453 INFO Dialect:92 - Using dialect: org.hibernate.dialect.MySQLDialect
05:15:34,453 INFO DriverManagerConnectionProvider:41 - Using Hibernate built-in connection pool (not for production use!)
05:15:34,453 INFO DriverManagerConnectionProvider:42 - Hibernate connection pool size: 10
05:15:34,453 INFO DriverManagerConnectionProvider:45 - autocommit mode: false
05:15:34,453 INFO DriverManagerConnectionProvider:80 - using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost/test
05:15:34,453 INFO DriverManagerConnectionProvider:86 - connection properties: {user=root, password=****}
05:15:34,453 INFO SchemaUpdate:105 - Running hbm2ddl schema update
05:15:34,453 INFO SchemaUpdate:117 - fetching database metadata
05:15:34,484 INFO SchemaUpdate:133 - updating schema
05:15:34,484 INFO Configuration:875 - processing extends queue
05:15:34,484 INFO Configuration:879 - processing collection mappings
05:15:34,484 INFO Configuration:888 - processing association property references
05:15:34,484 INFO Configuration:917 - processing foreign key constraints
05:15:34,515 INFO TableMetadata:38 - table found: test.department
05:15:34,515 INFO TableMetadata:39 - columns: [deptno, deptname]
05:15:34,515 INFO TableMetadata:40 - foreign keys: []
05:15:34,531 INFO TableMetadata:41 - indexes: [primary]
05:15:34,546 INFO TableMetadata:38 - table found: test.employee
05:15:34,546 INFO TableMetadata:39 - columns: [name, deptno, serialno]
05:15:34,546 INFO TableMetadata:40 - foreign keys: [fk4afd4ace59c8ae38]
05:15:34,546 INFO TableMetadata:41 - indexes: [fk4afd4ace59c8ae38, primary]
05:15:34,546 INFO SchemaUpdate:153 - schema update complete
05:15:34,546 INFO DriverManagerConnectionProvider:147 - cleaning up connection pool: jdbc:mysql://localhost/test
05:15:34,546 INFO SessionFactoryImpl:379 - Checking 0 named queries
05:15:34,625 ERROR BasicPropertyAccessor:115 - IllegalArgumentException in class: Department, getter method of property: Deptno
IllegalArgumentException occurred calling getter of Department.Deptno
05:15:34,640 DEBUG SQL:324 - insert into Department (DeptName, Deptno) values (?, ?)
Hibernate: insert into Department (DeptName, Deptno) values (?, ?)
05:15:34,671 DEBUG SQL:324 - update Employee set Deptno=?, name=? where serialno=?
Hibernate: update Employee set Deptno=?, name=? where serialno=?
05:15:34,671 ERROR BasicPropertyAccessor:115 - IllegalArgumentException in class: Department, getter method of property: Deptno
05:15:34,671 ERROR AbstractFlushingEventListener:277 - Could not synchronize database state with session
org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of Department.Deptno
at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:119)
at org.hibernate.tuple.AbstractTuplizer.getIdentifier(AbstractTuplizer.java:103)
at org.hibernate.persister.entity.BasicEntityPersister.getIdentifier(BasicEntityPersister.java:2944)
at org.hibernate.persister.entity.BasicEntityPersister.isTransient(BasicEntityPersister.java:2705)
at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:181)
at org.hibernate.engine.ForeignKeys.getEntityIdentifierIfNotUnsaved(ForeignKeys.java:215)
at org.hibernate.type.EntityType.getIdentifier(EntityType.java:99)
at org.hibernate.type.ManyToOneType.nullSafeSet(ManyToOneType.java:63)
at org.hibernate.persister.entity.BasicEntityPersister.dehydrate(BasicEntityPersister.java:1617)
at org.hibernate.persister.entity.BasicEntityPersister.update(BasicEntityPersister.java:1963)
at org.hibernate.persister.entity.BasicEntityPersister.updateOrInsert(BasicEntityPersister.java:1909)
at org.hibernate.persister.entity.BasicEntityPersister.update(BasicEntityPersister.java:2149)
at org.hibernate.action.EntityUpdateAction.execute(EntityUpdateAction.java:75)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:239)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:223)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:137)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:274)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:730)
at test.main(test.java:33)
Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:105)
... 19 more
Exception in thread "main" org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of Department.Deptno
at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:119)
at org.hibernate.tuple.AbstractTuplizer.getIdentifier(AbstractTuplizer.java:103)
at org.hibernate.persister.entity.BasicEntityPersister.getIdentifier(BasicEntityPersister.java:2944)
at org.hibernate.persister.entity.BasicEntityPersister.isTransient(BasicEntityPersister.java:2705)
at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:181)
at org.hibernate.engine.ForeignKeys.getEntityIdentifierIfNotUnsaved(ForeignKeys.java:215)
at org.hibernate.type.EntityType.getIdentifier(EntityType.java:99)
at org.hibernate.type.ManyToOneType.nullSafeSet(ManyToOneType.java:63)
at org.hibernate.persister.entity.BasicEntityPersister.dehydrate(BasicEntityPersister.java:1617)
at org.hibernate.persister.entity.BasicEntityPersister.update(BasicEntityPersister.java:1963)
at org.hibernate.persister.entity.BasicEntityPersister.updateOrInsert(BasicEntityPersister.java:1909)
at org.hibernate.persister.entity.BasicEntityPersister.update(BasicEntityPersister.java:2149)
at org.hibernate.action.EntityUpdateAction.execute(EntityUpdateAction.java:75)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:239)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:223)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:137)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:274)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:730)
at test.main(test.java:33)
Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:105)
... 19 more

-------------------------------------------------------------------------------------

Can Someone please have a look and tell me what the problem is ?

Thanks in advance.

I think taht you have an error in the classes definition.

You have to define a list in Department (I assume that you've got a one-to-many relationship beteween Department and Employees):
.

In Java classes you have to think in objects... so, this mapping can work:



Therefore you can navigate de Employees from a Department instances by de colletction getter.

Good luck [/quote]