NullPointerException when saving to GAE with RequestFactory

Question

I'm trying to persist a simple class with objectify but without success.

Apologies for the long post but I think more information is better than less.

I followed the example by David M. Chandler in:

http://turbomanage.wordpress.com/2011/03/25/using-gwt-requestfactory-with-objectify/

But I keep getting NullPointerException.

I don't know what I'm doing wrong but the classes I use are the following:

My proxies, DatastoreObjectProxy:

@ProxyFor(value = DatastoreObject.class, locator = ObjectifyLocator.class)
public interface DatastoreObjectProxy extends EntityProxy{

    Long getId();
    void setId(Long id);
    Integer getVersion();
    void setVersion(Integer id);

}

and BeingProxy:

@ProxyFor(value = Being.class, locator = ObjectifyLocator.class)
public interface BeingProxy extends DatastoreObjectProxy {

    String getName();
    void setName(String name);
    String getFiscalNumber();
    void setFiscalNumber(String fiscalNumber);

}

and my request factory:

public interface MyRequestFactory extends RequestFactory{

    @Service(value = BeingDao.class, locator = DaoServiceLocator.class)
    interface BeingRequestContext extends RequestContext {
        Request<List<BeingProxy>> listAll();
        Request<Void> save(BeingProxy being);
        Request<BeingProxy> saveAndReturn(BeingProxy being);
        Request<Void> removeBeing(BeingProxy being);
    }

    BeingRequestContext beingRequestContext();

}

Finally my UI uses the following code to create and retrieve a Being entity:

@UiHandler("btnAdd") void onBtnAddClick(ClickEvent event) {

    //Validate name
//TODO warn user if invalid
if (txtName==null||txtName.getText().equals("")){return;}
String n = txtName.getText();

//Validate fiscal number
//TODO warn user if invalid
if (txtFiscalNumber==null||txtFiscalNumber.getText().equals("")){return;}
String fn = txtFiscalNumber.getText();

BeingRequestContext reqCtx = rf.beingRequestContext();
final BeingProxy being = reqCtx.create(BeingProxy.class);
being.setName(n);
being.setFiscalNumber(fn);

Request<BeingProxy> saveRequest = reqCtx.saveAndReturn(being);
saveRequest.fire(new Receiver<BeingProxy>(){
    @Override
    public void onSuccess(BeingProxy response) {
        addToList(response);
    }
});

That throws the previous mentioned exception.

I've noted that the server code is note executed. So I guess the problem is in the request factory or in the client. But I triple checked the code and did not find anything wrong.

Thank you for your time.

Best Regards.

Answer 1

I figured this one out. I wasn't initializing the request factory properly. I had to initialize it with an event bus:

final MyRequestFactory rf = GWT.create(MyRequestFactory.class);

        EventBus eventBus = new SimpleEventBus();
        rf.initialize(eventBus);

Answer 2

You need to register your object classes in the objectify service for the locator to find them.

add the following code in ObjectifyLocator.java right after you declare the class:

public class ObjectifyLocator {
    static {
       ObjectifyService.register(DatastoreObject.class);
       ObjectifyService.register(Being.class);
     }

}