Bean created twice

[arungupta]

For a simple application, accessing http://localhost:8080/HelloConversation/faces/index.xhtml creates ShoppingCart twice. Any idea ?

Utility class is ...

@Named("util")
@ConversationScoped
public class ConvUtil implements Serializable {
     @Inject ShoppingCart cart;

     public ShoppingCart getCart() {
         return cart;
     }
}

index.xhtml has ...
                 <h:inputText value="#{util.cart}" title="name" id="name"
                              required="true" />


ShoppingCart is ...

@Named
@ConversationScoped
public class ShoppingCart implements Serializable {
     public ShoppingCart() {
         System.out.println("Creating shopping cart ..." + Calendar.getInstance().get(Calendar.MILLISECOND));
     }

}

At least the log messages like:

INFO: Creating shopping cart ...264
INFO: Creating shopping cart ...265

are printed.

Tried changing the scope of ShoppingCart to RequestScoped but still the same. Changed @Named to @javax.faces.bean.ManagedBean on ShoppingCart.

What am I not doing correctly ?

-Arun

[mbogoevici]

Hi Arun,

For every normal-scoped bean there is a proxy, In case, the proxy is a subclass of ShoppingCart, so what you see is the instantiation of two objects: one is the actual bean instance, the other one is the proxy (which being a subclass of ShoppingCart will invoke the no-arg constructor too),

Hope this helps,
Marius

[arungupta]

That helps explain the invocation of two constructors.

What is the purpose of this proxy ?

Do the users need to worry about this proxy or is purely for CDI runtime ?

-Arun

[mbogoevici]

No needs to worry about it, unless there are side-effects due to the duplicate instance construction (which, in general is a bad idea).

You can find more details about this here.

[niknik77771]

What if bean creation is expansive like database call? What is a Best Practices?

[ssachtleben.ssachtleben.gmail.com]

Dont use the constructor for database calls ...

@PostConstruct
public void initialize() {
  log.info("Just called once...");
}

[niknik77771]

Thank you very much Sebastian. Thats it.