When do you register classes in Objectify for GAE?

Question

So this might be kind of a dumb question but when do you register classes with:

ObjectifyService.register( User.class );

Currently, I\'m doing

Answer 1

I use the @Entity annotation, the Reflections library and runtime registration with no significant impact in start up time of any of my applications because all the information is collected at compile/build time.

ObjectifyLoaderContextListener.java

package com.vertigrated.servlet;
 
import com.google.appengine.api.ThreadManager;
import com.googlecode.objectify.ObjectifyFactory;
import com.googlecode.objectify.ObjectifyService;
import com.googlecode.objectify.annotation.Entity;
import org.reflections.Reflections;
import org.reflections.util.ClasspathHelper;
import org.reflections.util.ConfigurationBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
 
import javax.annotation.Nonnull;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
 
/**
 * This class processes the classpath for classes with the @Entity or @Subclass annotations from Objectify
 * and registers them with the ObjectifyFactory, it is multi-threaded uses a prebuilt list of classes to process
 * created by the Reflections library at compile time and works very fast!
 */
public class ObjectifyLoaderContextListener implements ServletContextListener
{
    private static final Logger L = LoggerFactory.getLogger(ObjectifyLoaderContextListener.class);
 
    private final Set<Class<?>> entities;
 
    public ObjectifyLoaderContextListener()
    {
        this.entities = new HashSet<>();
    }
 
    @Override
    public void contextInitialized(@Nonnull final ServletContextEvent sce)
    {
        final ConfigurationBuilder cb = new ConfigurationBuilder();
        cb.setUrls(ClasspathHelper.forPackage(""));
        final ExecutorService es = Executors.newCachedThreadPool(ThreadManager.currentRequestThreadFactory());
        cb.setExecutorService(es);
        final Reflections r = new Reflections(cb);
        this.entities.addAll(r.getTypesAnnotatedWith(Entity.class));
        es.shutdown();
        final ObjectifyFactory of = ObjectifyService.factory();
        for (final Class<?> cls : this.entities)
        {
            of.register(cls);
            L.debug("Registered {} with Objectify", cls.getName());
        }
    }
 
    @Override
    public void contextDestroyed(@Nonnull final ServletContextEvent sce)
    {
        /* this is intentionally empty */
    }
}

Answer 2

Based on Danie's answer and in case someone else is using dependency injection I did this for Spring MVC and worked perfect:

I created a service as follows:

@Service
@Qualifier("objectifyService")
public class OfyService {
    static {
        ObjectifyService.register(GaeUser.class);
    }

    public static Objectify ofy() {
        return ObjectifyService.ofy();
    }

    public static ObjectifyFactory factory() {
        return ObjectifyService.factory();
    }

}

Then whenever I want to use it I just inject the service like this:

@Autowired
@Qualifier("objectifyService")
OfyService objectifyService;

And then I use it like this:

objectifyService.ofy().save().entity(user).now();

Answer 3

Update

Here is the Best Practice Solution:

Use Your Own Service , This guarantees that your entities are registered before you use Objectify, but doesn't necessarily impact application startup for requests which do not access the datastore.

import com.googlecode.objectify.Objectify;
import com.googlecode.objectify.ObjectifyFactory;
import com.googlecode.objectify.ObjectifyService;


public class OfyService {
    static {
        ObjectifyService.register(User.class);
    }

    public static Objectify ofy() {
        return ObjectifyService.begin();//prior to v.4.0 use .begin() , 
                                        //since v.4.0  use ObjectifyService.ofy();
    }

    public static ObjectifyFactory factory() {
        return ObjectifyService.factory();
    }

}

Then use it like this:

public User createUser(User pUser) {

    Objectify objectify = OfyService.ofy();
    objectify.put(pUser);

    return pUser;
}

---

Original Answer (better use the code above):

you should do it this way in your class, just put a static block like this:

static{
    ObjectifyService.register( User.class );
}

p.s , you take a look at the best practice of objectify too

http://code.google.com/p/objectify-appengine/wiki/BestPractices