RequestFactory Eagerly Fetches the collections in my entity meant to loaded Lazy

[Aryan]

Hi all,

RequestFactory seems to fetch whatever the collection I have in my ValueProxy eagarly.

Lets see the code

 

@Entity

public class Venue implements Serializable {

 

     private name;
     private Address address;
     ....
    private  Set<VenueContact> contacts;
   
    @OneToMany(fetch = FetchType.LAZY)
    public Set<VenueContact> getVenueContactses() {
        return this.contacts;
    }

  //.... other getters and setters

}

Lets assume I have set everything else for RequestFactory and Hibernate (Hibernate standalone tests run fine) in order.

 

I call the below code from client:

 

requestFactory.venueRequest.findById(7).fire(new Reciever<VenueProxy>() {

 

                  public void onSuccess(VenueProxy res) {

                       log.info("I never get this :(");

                   }

});

 

In service method

 

public Venue findById() {

      //currently I am using a command pattern for a unit of transaction but anyway I just write simply whats happening

    

      // assume try catch and variable declaration code

 

      session = HibernateUtil.getSessionFactory.openSession();

      trx = session.getTrasaction();

      trx.beginTransaction();

      venue = veneuDao.findById(7);

      trx.commit();

      session.close();

}

 

##############################################################################################

Run Application and get this exception

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.xxxxx.xxxx.dto.Venue.contacts, no session or session was closed

 at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383)
 at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375)
 at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:368)
 at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:111)
 at org.hibernate.collection.PersistentSet.iterator(PersistentSet.java:186)
 at com.google.web.bindery.requestfactory.server.Resolver.resolveClientValue(Resolver.java:617)
 at com.google.web.bindery.requestfactory.server.Resolver.access$400(Resolver.java:50)
 at com.google.web.bindery.requestfactory.server.Resolver$PropertyResolver.visitReferenceProperty(Resolver.java:139)
 at com.google.web.bindery.autobean.shared.AutoBeanVisitor.visitCollectionProperty(AutoBeanVisitor.java:229)
 at com.google.web.bindery.autobean.vm.impl.ProxyAutoBean.traverseProperties(ProxyAutoBean.java:300)
 at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.traverse(AbstractAutoBean.java:166)
 at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.accept(AbstractAutoBean.java:101)
 at com.google.web.bindery.requestfactory.server.Resolver.resolveClientValue(Resolver.java:395)
 at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.processInvocationMessages(SimpleRequestProcessor.java:483)
 at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.process(SimpleRequestProcessor.java:225)
 at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.process(SimpleRequestProcessor.java:127)
 at com.google.web.bindery.requestfactory.server.RequestFactoryServlet.doPost(RequestFactoryServlet.java:133)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
 at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1097)
 at com.xxxxx.xxxxx.xxxxx.PersistenceFilter.doFilter(PersistenceFilter.java:35)
 at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1088)
 at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
 at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
 at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
 at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
 at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
 at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
 at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
 at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
 at org.mortbay.jetty.Server.handle(Server.java:324)
 at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
 at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
 at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
 at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
 at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
 at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
 at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)

###################################################################################################

 

But when I run the same kind of transaction under a test or under 'public static void main(..'  it does well.

 

Also I might have noticed somewhere in RequestFactory API we try to invoke all methods having collections, somewhere in highlighted text exceptions

 

As I have read the RequestFactory doc :

 

"When querying the server, RequestFactory does not automatically populate relations in the object graph. To do this, use the with() method on a request and specify the related property name as a String:".

 

I was expecting that the rule will also apply to Collections of related proxy.

 

 

Do I have to make a choice 1) have only eagarly fetch collection in proxy or 2) do not have any ?

 

I expect one suggestion may come out here to have a filter that maintains one transaction and session per request. But would it be good practice to have transaction per request.

 

 

In the end being too tired, I am just putting my question as short as possible. I am sorry if it doesn't appear very clear, in that case I can reply back to any quries.

 

 

 

Thanks in advance 

 

 

 

[Thomas Broyer]

Because a ValueProxy has no "identity" (and therefore cannot be retrieved again later), .with() doesn't apply to it; it only applies to EntityProxy.

[Aryan]

Thanks Thomas, You always been a great help... :)