NPE at getHibernateTemplate( )

[Hussein Baghdadi]

Hi.
My application using Spring and Hibernate as a persistenting technology.
Here is the class that uses Hibernate :

import org.springframework.orm.hibernate.support.HibernateDaoSupport;
 
public class StoringEvents extends HibernateDaoSupport implements Store {
 
public void storeEvents() throws DataAccessException {
LogEvent le = new LogEvent("Storing", new Date());
}
getHibernateTemplate().save(le);
}
}

In the application context, I created a datasource, a session factory, and an instance of
StoringEvents successfully (no excpetions throws).

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName">
<value>com.mysql.jdbc.Driver</value>
</property>
<property name="url">
<value>jdbc:mysql://localhost/eventsdb</value>
</property>
<property name="username">
<value>root</value>
</property>
<property name="password">
<value>root123</value>
</property>
</bean>
<bean id="sessionFactory" class="org.springframework.orm.hibernate.LocalSessionFactoryBean">
<property name="dataSource">
<ref local="dataSource"/>
</property>
<property name="mappingResources">
<value>com/spring/Verba.hbm.xml</value>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">net.sf.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
</bean>
<bean id="storer" class="com.spring.StoringEvents">
<property name="sessionFactory">
<ref local="sessionFactory"/>
</property>
</bean>

(It worth noting that I didn't create a transaction manager).
But when trying to run the application (web one), I got a NullPointerException at getHibernateTemplate().save(le);
The getHibernateTemplate( ) returns null.
Any ideas ?
Thanks.

[Gregg Bolinger]

So how do you suppose in your config your class is going to get injected with a HibernateTemplate object? I am using iBatis, but the concept is exactly the same. Here is my config...

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
 
<beans>
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName">
                <value>org.postgresql.Driver</value>
            </property>
            <property name="url">
                <value>jdbc:postgresql://localhost/pnp</value>
            </property>
            <property name="username">
                <value>admin</value>
            </property>
            <property name="password">
                <value>admin</value>
            </property>
        </bean>
 
         <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
            <property name="dataSource">
                <ref bean="dataSource"/>
            </property>
        </bean>
 
        <bean id="sqlMapClient" class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
            <property name="configLocation">
                <value>/WEB-INF/SqlMapConfig.xml</value>
            </property>
            <property name="dataSource">
                <ref bean="dataSource"/>
            </property>
        </bean>
 
        <bean id="sqlMapClientTemplate" class="org.springframework.orm.ibatis.SqlMapClientTemplate">
            <property name="sqlMapClient">
                <ref bean="sqlMapClient"/>
            </property>
        </bean>
 
        <!-- DAO Declarations  -->
 
        <bean id="typeDao" class="com.pnp.database.dao.ibatis.DefaultTypeDao">
            <property name="sqlMapClientTemplate">
                <ref bean="sqlMapClientTemplate"/>
            </property>
        </bean>
 
        <!-- Target Declarations  -->
 
        <bean id="typeServiceTarget" class="com.pnp.services.DefaultTypeService">
            <property name="typeDao">
                <ref bean="typeDao"/>
            </property>
        </bean>
 
 
        <!-- Service Declarations -->
 
        <bean id="typeService" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
            <property name="transactionManager">
                <ref bean="transactionManager"/>
            </property>
            <property name="target">
                <ref bean="typeServiceTarget"/>
            </property>
            <property name="transactionAttributes">
                <props>
                    <prop key="getType">PROPAGATION_REQUIRED</prop>
                </props>
            </property>
        </bean>
</beans>

[ January 14, 2006: Message edited by: Gregg Bolinger ]

[Hussein Baghdadi]

So, creating a transaction manager is mandatory ?
Please, check this :
http://www.coderanch.com/t/60069/oa/JSP-Servlets-Spring
My original problem originated here ...

[Gregg Bolinger]

One doesn't have anything to do with the other. You need to inject the HibernateTemplate object into your dao in order to use it.

[Ken Krebs]

Actually, the HibernateDaoSupport Javadoc says:

Convenient super class for Hibernate data access objects.

Requires a SessionFactory to be set, providing a HibernateTemplate based on it to subclasses. Can alternatively be initialized directly via a HibernateTemplate, to reuse the latter's settings like SessionFactory, exception translator, flush mode, etc.

This base class is mainly intended for HibernateTemplate usage but can also be used when working with SessionFactoryUtils directly, e.g. in combination with HibernateInterceptor-managed Sessions. Convenience getSession and releaseSession methods are provided for that usage style.

This class will create its own HibernateTemplate if only a SessionFactory is passed in. The allowCreate flag on that HibernateTemplate will be true by default. A custom HibernateTemplate instance can be used through overriding createHibernateTemplate.

So the configuration you've used should work without having to manually inject a HibernateTemplate. This technique is standard and is demonstrated in the PetClinic sample app. All the DaoSupport classes work this way. Perhaps something else is missing that is causing the NPE. Maybe you should post the full stack trace.

BTW, DriverManagerDataSource is not a pooling DataSource and is meant primarily for testing. PetClinic shows alternative DataSource definitions that provide pooled Connections you can use in a production environment.

[bob daly]

I'm experiencing the NPE on getHibernateTemplate as well - and having a difficult time finding out what my problem is.

I do not see any exceptions related to the sessionFactory
(org.springframework.orm.hibernate3.LocalSessionFactoryBean) on app start-up, and all of the Hibernate mappings seem to go smoothly.

I created a constructor in one of my classes that extends HibernateDAOSupport and call this.getSessionFactory; it's always null.

Any advice on how I should be troubleshooting this?

[Chris Mathews]

"rf daly"

Thanks for joining JavaRanch, please take some time to review the JavaRanch Name Policy then update your publicly displayed name in your profile so that it complies.

I would also suggest creating your own thread for questions instead of tacking onto an existing thread, if you feel that the problem is related it is probably helpful to include a link back to the original thread as well.