Question

My bean looks like that:

@Entity
public class Fattura {

    @Id
    Long id;

    @NotEmpty
    String numero;

    @Min(value=0)
    Double importo;

    Key<User> utente;

    // gets & sets....
}

The “utente” property is the key of another bean I created: a “Fattura” can have only one “User”, one “User” can have many “Fattura”s

My Spring MVC controller will manage a request for a list of Fattura and display them in a simple jsp:

@RequestMapping( value = "/fatture" , method = RequestMethod.GET )
    public ModelAndView leFatture() {

        ModelAndView mav = new ModelAndView("fatture");


        mav.addObject("fatture",fatturaService.listFatture());

        return mav;
    }

the code of the jsp is really simple: only a foreach cycle in a table

My question is:

how can I display the “utente”?

The only thing I have is its key, but I’d like to do something like ${fattura.utente.firstName} in my JSP, how can I do it?

Answer 1

Unfortunately you would have to manually fetch “utente” in your DAO class. There is no automatic fetching in Objectify like in Twig. In my POJOs I have following fields

@Transient private Organization sender;             // Pickup location (for client RPC)
transient private Key<Organization> senderKey;      // Pickup location (for Datastore)

I load entity from Datastore and then load manually Organization using senderKey.

In new Objectify4 you’ll be able to do what you want like this:

class Beastie {
   @Parent
   @Load
   ParentThing parent;

   @Id Long id;

   @Load({"bigGroup", "smallGroup"})
   SomeThing some;

   @Load("bigGroup")
   List<OtherThing> others;

   @Load
   Ref<OtherThing> refToOtherThing;

   Ref<OtherThing> anotherRef;  // this one is never fetched automatically
}

Here is evolving design document of new version.

Update at Nov 17, 2011: This is big news. Twig author, John Patterson, joined Objectify project today.