Problem with LazyInitializationException

[Muhammad Ramahy]

I get this exception:

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.itworx.twitter.model.User.messages, no session or session was closed
        at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:380)
        at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:372)
        at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:365)
        at org.hibernate.collection.AbstractPersistentCollection.write(AbstractPersistentCollection.java:205)
        at org.hibernate.collection.PersistentBag.add(PersistentBag.java:297)
        at com.itworx.twitter.model.User.addMessage(User.java:74)
        at com.itworx.twitter.dao.UserDao.saveMessage(UserDao.java:77)
        at com.itworx.twitter.dao.UserDao$$FastClassByCGLIB$$b94a7438.invoke(<generated>)
        at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191)
        at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:688)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterc
eptor.intercept(Cglib2AopProxy.java:621)
        at com.itworx.twitter.dao.UserDao$$EnhancerByCGLIB$$c39fc5d6.saveMessage(<generated>)
        at com.itworx.twitter.service.TwitterService.saveMessage(TwitterService.java:51)
        at com.itworx.twitter.controller.TileController.saveMessage(TileController.java:49)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
        at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
        at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
        at java.lang.Thread.run(Thread.java:662)

every time I try to execute this code:

	public boolean saveMessage(Message message,User user) {
		session =sessionFactory.openSession();
		try{
			System.out.println("I'm in dao");

                        //the exception is fired here
                        user.getMessages().add(message)
			user.setMessages(user.getMessages());
			session.saveOrUpdate(user);
			//session.saveOrUpdate(message);
		}catch (HibernateException e) {
			e.printStackTrace();
			System.out.println("Hibernate Exceptioun caught");
			return false;
		}finally{
			session.close();
		}
		System.out.println("true is returned");
			return true;
	}

I don't know what to do in order to avoid not having session or having multiple sessions and I wish Help

Regards,

[Rishi Shehrawat]

The exception is caused due to detached object. You will have to use session.merge() or session.lock() to attach the object to the session.

http://stackoverflow.com/questions/912659/what-is-the-proper-way-to-re-attach-detached-objects-in-hibernate

[Muhammad Ramahy]

It works! thank you, I would also want to say that if I've added

fetch=FetchType.EAGER

to the oneToMany annotation it will also work (that's what I'm currently doing).

[nivedan Nat]

Hi

But adding FetchType.Eager defeats the purpose of Lazy Loading. Depends where your using this object, probably associate the entity into session so that lazy loading can happen.