onetomany - hibernateTemplate

[Naresh Gunda]

Hi,
I have a problem with Spring-Hibernate one to many application.

I have saved Dept object ( parent).
To save an emp ( child ) object to the database, i am using dept.getEmps().add( emp). Here dept.getEmps() returns a Hash set.

When i use only hibernate API it is working fine. emp object is added to the database and it is added to dept children.

But when i use the same concept for hibernateTemplate it is not working. Can any one of you tell me the mistake in the application.

    
package beans;
 
import java.util.HashSet;
import java.util.Set;
 
public class Dept implements java.io.Serializable
{
 
    private Integer dno;
    private String  dname;
    private Set     emps = new HashSet(0);
 
    public Dept()
    {
        super();
    }
 
    public Dept(String dname, Set emps)
    {
        this.dname = dname;
        this.emps = emps;
    }
 
    public Integer getDno()
    {
        return this.dno;
    }
 
    public void setDno(Integer dno)
    {
        this.dno = dno;
    }
 
    public String getDname()
    {
        return this.dname;
    }
 
    public void setDname(String dname)
    {
        this.dname = dname;
    }
 
    public Set getEmps()
    {
        return this.emps;
    }
 
    public void setEmps(Set emps)
    {
        this.emps = emps;
    }
}

   
package beans;
 
public class Emp implements java.io.Serializable
{
    private Integer eno;
    private Dept    dept;
    private String  ename;
 
    public Emp()
    {
        super();
    }
 
    public Emp(Integer eno)
    {
        this.eno = eno;
    }
 
    public Emp(Integer eno, Dept dept, String ename)
    {
        this.eno = eno;
        this.dept = dept;
        this.ename = ename;
    }
 
    public Integer getEno()
    {
        return this.eno;
    }
 
    public void setEno(Integer eno)
    {
        this.eno = eno;
    }
 
    public Dept getDept()
    {
        return this.dept;
    }
 
    public void setDept(Dept dept)
    {
        this.dept = dept;
    }
 
    public String getEname()
    {
        return this.ename;
    }
 
    public void setEname(String ename)
    {
        this.ename = ename;
    }
 
}

 
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping>
<class name="beans.Dept" table="DEPT" schema="PUBLIC" lazy="false">
<id name="dno" type="integer">
<column name="DNO" />
<generator class="assigned"></generator>
</id>
<property name="dname" type="string">
<column name="DNAME" length="20" />
</property>
<set name="emps" inverse="true" lazy="false" cascade="all">
<key>
<column name="DNO" />
</key>
<one-to-many class="beans.Emp" />
</set>
</class>
</hibernate-mapping>

  
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping>
<class name="beans.Emp" table="EMP" schema="PUBLIC" lazy="false">
<id name="eno" type="integer">
<column name="ENO" />
<generator class="assigned" />
</id>
<many-to-one name="dept" class="beans.Dept" lazy="false" fetch="select" not-null="true" >
<column name="DNO" />
</many-to-one>
<property name="ename" type="string">
<column name="ENAME" length="20" />
</property>
</class>
</hibernate-mapping>

    
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
 
<beans>
 
<bean class="org.apache.commons.dbcp.BasicDataSource" id="myDataSource" lazy-init="false">
<property name="driverClassName">
<value>org.hsqldb.jdbcDriver</value>
</property>
<property name="url">
<value>jdbc:hsqldb:hsql://localhost/mydatabase</value>
</property>
<property name="username">
<value>sa</value>
</property>
<property name="password">
<value></value>
</property>
</bean>
 
<!-- Hibernate SessionFactory -->
<bean id="mySessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource">
<ref local="myDataSource" />
</property>
<property name="mappingResources">
<list>
<value>mappings/Dept.hbm.xml</value>
<value>mappings/Emp.hbm.xml</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.HSQLDialect</prop>
<prop key="hibernate.hbm2ddl.auto">create</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.connection.autocommit">true</prop>
</props>
</property>
</bean>
 
<!-- Hibernate Template -->
<bean class="org.springframework.orm.hibernate3.HibernateTemplate" id="hibernateTemplate">
<property name="sessionFactory">
<ref bean="mySessionFactory" />
</property>
</bean>
 
</beans>

   
package utest;
 
import junit.framework.TestCase;
 
import org.hibernate.Session;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.dao.DataAccessException;
import org.springframework.orm.hibernate3.HibernateTemplate;
 
import beans.Dept;
import beans.Emp;
 
public class MyTest extends TestCase
{
 
    HibernateTemplate hibernateTemplate;
 
    Dept              dept;
 
    public MyTest(String arg0)
    {
        super(arg0);
    }
 
    protected void setUp() throws Exception
    {
        super.setUp();
        final String[] configLocations = new String[1];
        configLocations[0] = "mappings/spring-hibernate.xml";
        final ApplicationContext appContext = new ClassPathXmlApplicationContext(configLocations);
        hibernateTemplate = (HibernateTemplate) appContext.getBean("hibernateTemplate");
        dept = new Dept();
        dept.setDno(10);
        dept.setDname("dept1");
        hibernateTemplate.save(dept);
    }
 
    public void testAddEmps()
    {
        Dept dept = (Dept) hibernateTemplate.load(Dept.class, new Integer(10));
        final Emp emp = new Emp();
        emp.setEno(100);
        emp.setEname("name1");
        emp.setDept(dept);
        dept.getEmps().add(emp);
        Emp loded_emp=(Emp)hibernateTemplate.load(Emp.class, new Integer(100));
        assertEquals(emp,loded_emp);
    }
}
 

Problem is, emp is getting added to dept's hashset but not to the database.
When i use hibernateTemplate.update(dept), emp is getting added to the database here. But when i use only hibernateAPI i.e. with out springs, with out using session.update(dept), emp is getting added to database. can you pls tell me the mistake in this application.

[Manuel Jordan]

Hello Naresh

I have saved Dept object ( parent).
To save an emp ( child ) object to the database, i am using dept.getEmps().add( emp). Here dept.getEmps() returns a Hash set.

parent and child, where??? i dont understand, in your mapping files i see a simple relation and looks good.

When i use hibernateTemplate.update(dept), emp is getting added to the database here. But when i use only hibernateAPI i.e. with out springs, with out using session.update(dept), emp is getting added to database. can you pls tell me the mistake in this application.

the correct way is using the "update method", mistake???, no exist i think so.

maybe this is wrong , long time ago that i dont work with hibernate alone,
i work with Spring/Hibernate
but i can remember and you see this behaviour: you can update into the db only with Hibernate without use update method, why??, this is a feature of Hibernate, automatic update into the dabase when the state of the object (values of the properties) is changed

in Spring not happens, you must use the hibernateTemplate

regards