Saving an object via getSessionFactory().getCurrentSession().save(item) - spring

Question

Even if the operation seems to be extremely frequently used I haven't found where is the problem in my code.
In DAO class I have:
public class ItemDaoImpl extends HibernateDaoSupport implements ItemDao {
#Transactional
public void addItem(Item item){
getSessionFactory().getCurrentSession().save(item);
}
#Transactional(readOnly = true)
public List<Item> findAllItem(){
return getSessionFactory().getCurrentSession().createQuery("from Item").list();
}}
findAllItem() works well, whereas addItem() doesn't. When I click a button that invokes addItem() the following error is thrown:
java.lang.ClassCastException: com.z.item.model.Item cannot be cast to java.util.Map
javax.faces.el.EvaluationException: java.lang.ClassCastException: com.z.item.model.Item cannot be cast to java.util.Map
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:98)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:98)
at javax.faces.component.UICommand.broadcast(UICommand.java:311)
.
.
.
But I haven't specified any Map as I use the object "Item" everywhere. Item object that is passed to addItem() is also correct. Why is this exception thrown?
Here is how I configure it:
<hibernate-mapping>
<class entity-name="com.z.item.model.Item"
table="item">
<id name="id" type="long">
<column name="ID" />
<generator class="identity" />
</id>
<property name="name" type="string">
<column name="ITEMNAME" length="45" not-null="true" />
</property>
<property name="amount" type="int">
<column name="AMOUNT" not-null="true" />
</property>
<property name="price" type="java.math.BigDecimal">
<column name="PRICE" length="10" not-null="true" />
</property>
</class>
</hibernate-mapping>
<tx:annotation-driven transaction-manager="transactionManager"/>
<bean id="transactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"></property>
</bean>
<bean id="itemDao"
class="com.z.item.dao.impl.ItemDaoImpl" >
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource">
<ref bean="dataSource"/>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.HSQLDialect</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
<property name="mappingResources">
<list>
<value>com/z/item/hibernate/Item.hbm.xml</value>
</list>
</property>
</bean>

Answer 1

I don't think this is an issue caused with Hibernate. The issue may already have happened when you click the button and BEFORE reaching addItem(). Most likely, it is data mapping issue(I assume you map some data to Item first when clicking the button). Try to print out item before you call addItem(), you should see above exception even not calling addItem().

Answer 2

For the #Transactional annotation you need to specify your write (save and delete) DAO methods with false and your read (get and load) methods with true.
The #Transactional is simply adding certain meta data for the method or class about whether the transaction is read only or write or whether it requires a new transaction etc.. for more information on the #Transactional annotation please read here.
#Transactional(readOnly=false)
public void addItem(Item item){
getSessionFactory().getCurrentSession().save(item);
}
#Transactional(readOnly=true)
public List<Item> findAllItem(){
return getSessionFactory().getCurrentSession().createQuery("from Item").list();
}
Also, you should change your mapping to use <class name="Item" table="item"> instead of <class entity-name="com.z.item.model.Item" table="item">. This mapping allows you to access the data as a dom4j tree, or as a graph of property name/value pairs or java Maps. Specifying only an XML mapping without any associated class. The property names are purely logical constructs that can be referred to in HQL queries. See the hibernate doco for more info.
entity-name (optional - defaults to the class name): Hibernate3 allows
a class to be mapped multiple times, potentially to different tables.
It also allows entity mappings that are represented by Maps or XML at
the Java level. In these cases, you should provide an explicit
arbitrary name for the entity. See Section 4.4, “Dynamic models” and
Chapter 18, XML Mapping for more information.

Answer 3

Actually, there were a couple of things I did to make this code working.
I've changed my dao method to:
#Transactional(readOnly=false)
public void addItem(Item item){}
I've modified cglib version in pom.xml from 2.2. to 2.1.
I've changed the configuration to:
<class name="pl.outbox.item.model.Item" table="item">
<id name="id" type="int">
<column name="ID" />
<generator class="increment"/>
</id>