Error when using @SessionScoped and @Entity Annotation

[janey]

Hey all,

i am trying to implement a simple WELD example with a jsf page to add a new account to the dateabase. My Problem is that as soon as I use a scope-annotation e.g. @SessionScoped and a @Entity Annotation I get following error when I try to perist the Account Object:

20:47:15,700 ERROR Faces Servlet Servlet.service() for servlet Faces Servlet threw exception
 java.lang.IllegalArgumentException: Unknown entity: bankgroupServer.Account_$$_javassist_23
       at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:311)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
       at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

The head of my Account.java looks like this:

@SessionScoped
 @Named
 @Entity
 @Table(name = "tbl_Account")
 public class Account implements Serializable
 {    
        private static final long serialVersionUID = 1L;
        
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private int accountNumber;
        
        private float amount = 0;
 [...]
 }

My jsf-page looks like:

<h:form id="account" styleClass="edit">

        <rich:panel>
            <f:facet name="header">#{account.managed ? 'Edit' : 'Add'} Account</f:facet>            
            Amount:
            <h:inputText id="amountId" required="true" value="#{account.amount}" />                
        </rich:panel>

        <div class="actionButtons">

            <h:commandButton id="save"
                          value="Save"
                         action="#{accountManager.createAccount}"
                       rendered="#{!account.managed}"/>
        </div>
    </h:form>

My AccountBean.java looks like:

@Named("accountManager")
@SessionScoped
@Stateful
public class AccountBean implements Serializable, IAccountBeanLocal 
{
        private static final long serialVersionUID = 1L;
        @Inject Account account;
        @Inject @BankDatabase EntityManager database;
        
    /**
     * Default constructor. 
     */
    public AccountBean() {
        // TODO Auto-generated constructor stub
    }

    /**
     * 
     */
    public void createAccount()
    {
        System.out.println(account.getAmount()); // --> Test if injection was correct
        database.persist(account); // --> Error occurs
    }
    
    @Remove
    public void destroy()
    {
    }
}

If I leave out the @SessionSyoped annotation in Account.java, I am able to persist the Account object without errors, but the account object I filled with the amount-value from the jsf page won't be injected but a new one will be created.

Am I doing something principally wrong? Am I not able to use @Entity's with a scope??? Why can't the Entity be found if I define a scope?

I guess if I use two diffenrent classes, one for the entity to persist and one for the bean that takes the values from the jsf page. I would need to copy the values from the one class to the entity class and then call persist. I guess that would work but do I really need 2 classes for one purpose????

If you need the persistent.xml or anything else please just ask me to and I will post it.

I can't get rid of the error above an I cant guess of working solution.  I need your help :)

[alin.heyoulin.qq.com]

Scoped managed bean is javassist proxy. So you persist a javassist proxy rather than the entity. You can try @SessionScoped @Produces

[gavin.king]

Right, we recommend against using scope annotations on entities.

[janey]

Thank you for your quick replies.

Sorry, but I am not sure if I understand you right.... where exactely do I habe to use the @SessionScoped @Produces? Should I completely delete the @SessionScoped annotation from the entity?

[alin.heyoulin.qq.com]

@Entity
 @Table(name = "tbl_Account")
 public class Account implements Serializable
 {    
        private static final long serialVersionUID = 1L;
        
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private int accountNumber;
        
        private float amount = 0;
 [...]
 }


@Named("accountManager")
@SessionScoped
@Stateful
public class AccountBean implements Serializable, IAccountBeanLocal 
{
        private static final long serialVersionUID = 1L;
        @Inject Account account;
        @Inject @BankDatabase EntityManager database;
        
    /**
     * Default constructor. 
     */
    public AccountBean() {
        // TODO Auto-generated constructor stub
    }

    /**
     * 
     */
    public void createAccount()
    {
        System.out.println(account.getAmount()); // --> Test if injection was correct
        database.persist(account); // --> Error occurs
    }
    
    @Remove
    public void destroy()
    {
    }
    
    
    @SessionScoped @Produces
    Account getAccount()
    {
       return new Account();
    }

}

[janey]

Thanks he youlin.

I tried to use the @Produces @SessionScoped annotation within the AccountBean class. I changed the Account entity as you showed. When I use the classes as posted I am getting an "ambiguous dependencies" error (WELD wants a decision between Account() constructor and AccountBean.getAccount() ). To resolve the error I added a new qualifier @Preferred:

`
@Named("accountManager")
@SessionScoped
@Stateful
public class AccountBean implements Serializable, IAccountBeanLocal
{
    /**
     *
     */
    private static final long serialVersionUID = 1L;

    /**
     *
     */
    @Inject @Preferred Account account;

    [...]

    /**
     *
     */
    public void createAccount()
    {
         System.out.println(account.getAmount());
         database.persist(account);
    }
   
    /**
     *
     * @return
     */
    @Produces @SessionScoped @Preferred
    public Account getAccount()
    {
       return new Account();
    }
}
`

But it still doesn't work. The Account object is not available in EL and in the AccountEdit.xhml. I am getting the Error:

'16:03:18,377 WARNING [lifecycle] /AccountEdit.xhtml @19,84 value="#{account.amount}": Target Unreachable, identifier 'account' resolved to null'

I thought this is because the @Named annotation is missing and added @Named to the getAccount() Method.

'    /**
     *
     * @return
     */
    @Produces @SessionScoped @Preferred @Named
    public Account getAccount()
    {
       return new Account();
    }
'

But this leads me again to the error of my first post:

'16:09:56,593 SEVERE [application] java.lang.RuntimeException: Error invoking method createAccount on interface bankgroupServer.IAccountBeanLocal
javax.faces.el.EvaluationException: java.lang.RuntimeException: Error invoking method createAccount on interface bankgroupServer.IAccountBeanLocal
     at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
     at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
     at javax.faces.component.UICommand.broadcast(UICommand.java:315)
[...]
Caused by: javax.ejb.EJBException: java.lang.IllegalArgumentException: Unknown entity: bankgroupServer.Account_$$_javassist_23
     at org.jboss.ejb3.tx.Ejb3TxPolicy.handleExceptionInOurTx(Ejb3TxPolicy.java:77)
     at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:83)
     at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:190)

'

What is still wrong? I just want to open an xhtml page, create an account and persist it using a persistent entity.

I really want to understand WELD, but I don't get the point. I still need your help. Please :)

[alin.heyoulin.qq.com]

Sorry. I just show you how to use @Produces. I know it doesn't work. I just think you understood @Produces.

@Produces generally in individual class. So you can use as


public class someclass{
@Produces @SessionScoped @Named("account")
    public Account getAccount()
    {
       return new Account();
    }
}
If you use it in el. You can add @Name("something")

[janey]

Thanks for your answer.

Did you read my complete post? I did what you just said but it still doesn't work. I know how to use @Produces. But it seems, that this still does not solve my problem. As I posted before, when I add @Named or @Named(account) (what both should be the same) I am facing again the same problem as described in my very first post. So the use of a @Produces method finally did not change anything.

Scoped managed bean is javassist proxy. So you persist a javassist proxy rather than the entity. You can try @SessionScoped @Produces

I principially understand that. But maybe I am too stupid to implement it in the right way.

Any other suggestions?

[alin.heyoulin.qq.com]

Sounds Scoped Produces is proxy object too. I test as:

public class someclass{
@Produces @SessionScoped @Named("account")
    public Account getAccount()
    {
       return new Account();
    }
}


@Named("accountManager")
@SessionScoped
@Stateful
public class AccountBean implements Serializable, IAccountBeanLocal 
{
        private static final long serialVersionUID = 1L;
        @Inject @Named("account") Account account;
        @Inject @BankDatabase EntityManager database;
        
    /**
     * Default constructor. 
     */
    public AccountBean() {
        // TODO Auto-generated constructor stub
    }

    /**
     * 
     */
    public void createAccount()
    {
        System.out.println(account.getAmount()); // --> Test if injection was correct
        database.persist(account); // --> Error occurs
    }
    
    @Remove
    public void destroy()
    {
    }
  }

throw Unknown entity. 

I have no idea. :)

[meetoblivion]

And it should...

You have to think about why you need a producer method.  All it does is wraps your beans in some potential BL that maybe executed - and is probably best used with objects that you don't control.  You're still doing the same thing in both cases. 

You can try to produce a dependent scoped object, or you can use it as a member of an object.

[janey]

Finally it makes sense that the same error occures. Sometimes you need to do it step by step to understand a thing.

As a dependend scope it works, but i need a scope unlike dependend to inject the object into my account bean keeping its values.

So is there no way to use a persistent entity in an EL context and persist it afterwards? Do I really need 2 classes? One as javassist proxy and one as entity class to persist?

[meetoblivion]

You could use a facade

@Stateful
@SessionScoped
@Named("something")
public class MyEntityFacade {
   private MyEntity myEntity;
   //put in code that inits your entity
   public void save() { /* do your save logic */ }
   public MyEntity getMyEntity() { return myEntity; }

}

best I can think of.

[gavin.king]

Janey Masters wrote on Jan 09, 2010 20:09:


So is there no way to use a persistent entity in an EL context and persist it afterwards? Do I really need 2 classes? One as javassist proxy and one as entity class to persist?

This is definitely a way. You instantiate the entity inside another bean (with whatever scope is appropriate), and expose it to EL using @Produces. For example:

@RequestScoped @Named
public class NewUserAction {
   @Inject EntityManager em;

   @Produces @Named
   private User newUser = new User();

   public persist() {
      em.persist(newUser);
   }
}

Now you can refer to the User as #{newUser} in EL, and persist it using #{newUserAction.persist}. Easy!

Note that I'm going to write a portable extension to automagically register EntityHome beans for all beans in the application, so that you don't have to write code like this. Not sure of the details yet, I have to find time to think about it.

[alin.heyoulin.qq.com]

So is the newUser RequestScoped ?

[janey]

Thank you all for your replies :)

I will try your example Gavin. Thanks for posting!

You helped me out of my black hole :)