Hibernate Lazy initialization exception problem with Gilead in GWT 2.0 integration
- by sylsau
Hello,
I use GWT 2.0 as UI layer on my project. On server side, I use Hibernate. For example, this is 2 domains entities that I have :
public class User {
private Collection<Role> roles;
@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "users", targetEntity = Role.class)
public Collection<Role> getRoles() {
return roles;
}
...
}
public class Role {
private Collection<User> users;
@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, targetEntity = User.class)
public Collection<User> getUsers() {
return users;
}
...
}
On my DAO layer, I use UserDAO that extends HibernateDAOSupport from Spring. UserDAO has getAll method to return all of Users.
And on my DAO service, I use UserService that uses userDAO to getAll of Users.
So, when I get all of Users from UsersService, Users entities returned are detached from Hibernate session. For that reason, I don't want to use getRoles() method on Users instance that I get from my service.
What I want is just to transfer my list of Users thanks to a RPC Service to be able to use others informations of Users in client side with GWT.
Thus, my main problem is to be able to convert PersistentBag in Users.roles in simple List to be able to transfer via RPC the Users. To do that, I have seen that Gilead Framework could be a solution.
In order to use Gilead, I have changed my domains entities. Now, they extend net.sf.gilead.pojo.gwt.LightEntity and they respect JavaBean specification.
On server, I expose my services via RPC thanks to GwtRpcSpring framework (http://code.google.com/p/gwtrpc-spring/). This framework has an advice that makes easier Gilead integration.
My applicationContext contains the following configuration for Gilead :
<bean id="gileadAdapterAdvisor" class="org.gwtrpcspring.gilead.GileadAdapterAdvice" />
<aop:config>
<aop:aspect id="gileadAdapterAspect" ref="gileadAdapterAdvisor">
<aop:pointcut id="gileadPointcut"
expression="execution(public * com.google.gwt.user.client.rpc.RemoteService.*(..))" />
<aop:around method="doBasicProfiling" pointcut-ref="gileadPointcut" />
</aop:aspect>
</aop:config>
<bean id="proxySerializer" class="net.sf.gilead.core.serialization.GwtProxySerialization" />
<bean id="proxyStore" class="net.sf.gilead.core.store.stateless.StatelessProxyStore">
<property name="proxySerializer" ref="proxySerializer" />
</bean>
<bean id="persistenceUtil" class="net.sf.gilead.core.hibernate.HibernateUtil">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
<bean class="net.sf.gilead.core.PersistentBeanManager">
<property name="proxyStore" ref="proxyStore" />
<property name="persistenceUtil" ref="persistenceUtil" />
</bean>
The code of the the method doBasicProfiling is the following :
@Around("within(com.google.gwt.user.client.rpc.RemoteService..*)")
public Object doBasicProfiling(ProceedingJoinPoint pjp) throws Throwable {
if (log.isDebugEnabled()) {
String className = pjp.getSignature().getDeclaringTypeName();
String methodName = className
.substring(className.lastIndexOf(".") + 1)
+ "." + pjp.getSignature().getName();
log.debug("Wrapping call to " + methodName
+ " for PersistentBeanManager");
}
GileadHelper.parseInputParameters(pjp.getArgs(), beanManager,
RemoteServiceUtil.getThreadLocalSession());
Object retVal = pjp.proceed();
retVal = GileadHelper.parseReturnValue(retVal, beanManager);
return retVal;
}
With that configuration, when I run my application and I use my RPC Service that gets all of Users, I obtain a lazy initialization exception from Hibernate from Users.roles.
I am disappointed because I thought that Gilead would let me to serialize my domain entities even if these entities contained PersistentBag.
It's not one of the goals of Gilead ?
So, someone would know how to configure Gilead (with GwtRpcSpring or other solution) to be able to transfer domain entities without Lazy exception ?
Thanks by advance for your help.
Sylvain
