How to use Morphia with Java / GWT

Question

I am trying to use MongoDB with Morphia as my back-end DB, I have implemented a utility class to simplify access to the database. I implemented basic add user function with However I am getting `lots of exceptions:

java.lang.IndexOutOfBoundsException exception when I put

Query query = datastore.createQuery(User.class).filter("name = ", username);

for checking user before comitting.

When removed: I get these two exceptions:

java.lang.RuntimeException: java.lang.NumberFormatException:

How to fix this issue?

Here are the code I have for the project:

MorphiaUtil.java:

public class MorphiaUtil {

    protected final Log log = LogFactory.getLog(getClass());
    private static Mongo mongo;
    private static Datastore datastore;

    static {
        try {
            // Create the database connection
            mongo =  new Mongo("localhost");
            datastore = new Morphia().createDatastore(mongo, "mygwtapp");
        } catch (UnknownHostException e) {
            System.err.println("Caught Unknown host exception:"+e);
            e.printStackTrace();
        } catch (MongoException e) {
            System.err.println("Initial Datastore creation failed:"+e);
            e.printStackTrace();
        }
    }

    public static Datastore getDatastore() {
        return datastore;
    }
}

UserServiceImpl.java

public class UserServiceImpl extends RemoteServiceServlet 
    implements UserService {
    @Override
    public void addUser(String username, String password)
            throws IllegalArgumentException {
        try {
            Datastore datastore = MorphiaUtil.getDatastore();
            Query query = datastore.createQuery(User.class).filter("name = ", username); 
            User user = (User) query.asList().get(0);
            if (user == null) {
                user = new User(username, password);
                datastore.save(user);
            }

        } catch (Exception e) { 
            System.err.print("Caught exception:"+e);
        }
    }
}

Answer 1

I created a server version of all my beans, and before calling saving methods, i convert from Simple Beans (used in client side) to MorphiaBeans (used only for morphia operations).

That's not the best method to fix this issue, but works fine for me!