GenericServiceImpl.java

package org.appfuse.gwt.service.client.service;

import org.appfuse.gwt.service.client.event.CollectionLoadedEvent;
import org.appfuse.gwt.service.client.event.ResourceDeletedEvent;
import org.appfuse.gwt.service.client.event.ResourceLoadedEvent;
import org.appfuse.gwt.service.client.event.ResourceSavedEvent;
import org.appfuse.gwt.service.client.rest.Callback;
import org.appfuse.gwt.service.client.rest.Deferred;
import org.appfuse.gwt.service.client.rest.Representation;
import org.appfuse.gwt.service.client.rest.RestRequest;
import org.appfuse.gwt.service.client.rest.jso.AbstractJSOModel;
import org.appfuse.gwt.service.client.rest.jso.JSOModel;
import com.google.gwt.core.client.JsArray;
import com.google.gwt.http.client.URL;
import net.customware.gwt.presenter.client.EventBus;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

/**
 * This class serves as the Base class for GWT Services - namely to hold
 * common CRUD methods that they might all use. You should only need to extend
 * this class when your require custom CRUD logic.
 *
 * @author mraible
 * @param <M> a Model that extends AbstractJSOModel
 * @param <PK> the primary key for that type
 */
public abstract class GenericServiceImpl<M extends AbstractJSOModel, PK extends Serializable>
        implements GenericService<M, PK> {

    /**
     * EventBus instance, set by constructor of this class
     */
    protected EventBus eventBus;
    /**
     * URL of server-side resource location
     */
    protected String location;

    /**
     * Public constructor for creating a new GenericServiceImpl.
     *
     * @param eventBus the EventBus to use for firing Events
     * @param location the URL of the service
     */
    public GenericServiceImpl(final EventBus eventBus, String location) {
        this.eventBus = eventBus;
        this.location = location;
    }

    /**
     * {@inheritDoc}
     */
    public void getAll() {
        Deferred<Representation> d = RestRequest.get(location).build();

        d.addCallback(new Callback<Representation>() {
            public void onSuccess(Representation result) {
                JsArray<JSOModel> array = JSOModel.arrayFromJson(result.getData());
                List<M> models = new ArrayList<M>();
                for (int i = 0; i < array.length(); i++) {
                    models.add(convertResultToModel(array.get(i)));
                }
                eventBus.fireEvent(new CollectionLoadedEvent<M>(models));
            }
        });

        d.run();
    }

    /**
     * {@inheritDoc}
     */
    public void get(PK id) {
        Deferred<Representation> d =
                RestRequest.get(location + "/" + URL.encode(id.toString())).build();

        d.addCallback(new Callback<Representation>() {
            public void onSuccess(Representation result) {
                M model = convertResultToModel(result);
                eventBus.fireEvent(new ResourceLoadedEvent<M>(model));
            }
        });

        d.run();
    }

    /**
     * {@inheritDoc}
     */
    public void save(M model) {
        Deferred<Representation> d = RestRequest.post(location)
                .setRequestData(model.toJson()).build();

        d.addCallback(new Callback<Representation>() {
            public void onSuccess(Representation result) {
                M model = convertResultToModel(result);
                eventBus.fireEvent(new ResourceSavedEvent<M>(model));
            }
        });

        d.run();
    }

    /**
     * {@inheritDoc}
     */
    public void delete(PK id) {
        Deferred<Representation> d =
                RestRequest.post(location + "/" + URL.encode(id.toString())).build();

        d.addCallback(new Callback<Representation>() {
            public void onSuccess(Representation result) {
                eventBus.fireEvent(new ResourceDeletedEvent());
            }
        });

        d.run();
    }

    /**
     * Method to convert Representation to a model object.
     *
     * @param result the result of a resource request.
     * @return the populated object.
     */
    @SuppressWarnings("unchecked")
    protected M convertResultToModel(Representation result) {
        return convertResultToModel(JSOModel.fromJson(result.getData()));
    }

    /**
     * Method to convert a JSOModel to an AbstractJSOModel
     *
     * @param data a JSOModel object
     * @return the populated model object.
     */
    @SuppressWarnings("unchecked")
    protected abstract M convertResultToModel(JSOModel data);
}