RequestFactory => UnexpectedException: The persisted entity with id 0 has a null version

[Alexander Orlov]

Dev Mode initialized. Startup URL:
http://127.0.0.1:8888/?gwt.codesvr=127.0.0.1:9997
May 18, 2011 5:41:12 PM
com.google.web.bindery.requestfactory.server.RequestFactoryServlet
doPost
SEVERE: Unexpected error
com.google.web.bindery.requestfactory.server.UnexpectedException: The
persisted entity with id 0 has a null version
[...]
[ERROR] 500 - POST /gwtRequest (127.0.0.1) 1420 bytes
#########################

...is what I get.

my web.xml:

    <servlet>
        <servlet-name>requestFactoryServlet</servlet-name>
        <servlet-
class>com.google.web.bindery.requestfactory.server.RequestFactoryServlet</
servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>requestFactoryServlet</servlet-name>
        <url-pattern>/gwtRequest</url-pattern>
    </servlet-mapping>

my server/AvailabilityLocator.java:

import com.google.web.bindery.requestfactory.shared.Locator;
import dp.verp.model.Availability;

public class AvailabilityLocator extends Locator<Availability, Long> {
    @Override
    public Availability create(Class<? extends Availability> aClass) {
        return new Availability();
    }

    @Override
    public Availability find(Class<? extends Availability> aClass,
Long aLong) {
        return new Availability();
    }

    @Override
    public Class<Availability> getDomainType() {
        return null;
    }

    @Override
    public Long getId(Availability availability) {
        return Long.parseLong(String.valueOf(availability.getId()));
    }

    @Override
    public Class<Long> getIdType() {
        return null;
    }

    @Override
    public Object getVersion(Availability availability) {
        return null;
    }
}

my server/MyServiceLocator:

import com.google.web.bindery.requestfactory.shared.ServiceLocator;

public class MyServiceLocator implements ServiceLocator {
    /**
     * Returns an instance of the service object.
     *
     * @param clazz the requested type of service object
     * @return an instance of the service object
     */
    @Override
    public Object getInstance(Class<?> clazz) {
        try {
            return clazz.newInstance();
        } catch (InstantiationException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }
}

my shared/AvailabilityProxy.java:

import com.google.web.bindery.requestfactory.shared.EntityProxy;
import com.google.web.bindery.requestfactory.shared.ProxyFor;
import dp.verp.model.Availability;
import dp.verp.view.availability.server.AvailabilityLocator;

@ProxyFor(value = Availability.class, locator =
AvailabilityLocator.class)
public interface AvailabilityProxy extends EntityProxy {
    int getId();

    void setSchedule(String schedule);

    String getSchedule();
}

my shard/AvailabilityRequest:

import com.google.web.bindery.requestfactory.shared.InstanceRequest;
import com.google.web.bindery.requestfactory.shared.Request;
import com.google.web.bindery.requestfactory.shared.RequestContext;
import com.google.web.bindery.requestfactory.shared.Service;
import dp.verp.model.Availability;
import dp.verp.view.availability.server.MyServiceLocator;

@Service(value = Availability.class, locator = MyServiceLocator.class)
public interface AvailabilityRequest extends RequestContext {
    InstanceRequest<AvailabilityProxy, Void> persist();
}

my shared/AvailabilityRequestFactory.java:

import com.google.web.bindery.requestfactory.shared.InstanceRequest;
import com.google.web.bindery.requestfactory.shared.RequestContext;
import com.google.web.bindery.requestfactory.shared.RequestFactory;
import com.google.web.bindery.requestfactory.shared.Service;
import dp.verp.model.Availability;

public interface AvailabilityRequestFactory extends RequestFactory {
    /**
     * Source of request objects for the Person class.
     */
    @Service(Availability.class)
    interface PersonRequest extends RequestContext {
        InstanceRequest<AvailabilityProxy, Void> persist();
    }

    AvailabilityRequest availabilityRequest();
}

my model/Availability.java:

@Entity
public class Availability {
    @Id
    private int id;
    private String schedule;

  public void persist() {
    EntityManager em = Database.getEntityManager();
    try {
        em.persist(this);
    } finally {
      em.close();
    }
  }
    public int getId() {
        return id;
    }

    public String getSchedule() {
        return schedule;
    }

    public void setSchedule(String schedule) {
        this.schedule = schedule;
    }
}

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

And here is my call from the presenter class:

        EventBus eventBus = new SimpleEventBus();
        AvailabilityRequestFactory requestFactory =
GWT.create(AvailabilityRequestFactory.class);
        requestFactory.initialize(eventBus);

        AvailabilityRequest request =
requestFactory.availabilityRequest();
        AvailabilityProxy availabilityProxy =
request.create(AvailabilityProxy.class);
        Request<Void> createReq =
request.persist().using(availabilityProxy);


        createReq.fire(new Receiver<Void>() {
            @Override
            public void onSuccess(Void response) {

            }
        });

Btw does anybody know a working&minimalistic example that implements
the RequestFactory paradigm?

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