I've been trying to get the example code from the Morphia Website working with very little success, I was wondering why the following code snippet fails?
public class DBUtil {
private static Mongo mongo;
private static Datastore ds;
private static Morphia morphia;
public static void main(String[] args) {
try {
mongo = new MongoClient(new ServerAddress(Consts.DatabaseHost,
Consts.DatabasePort));
morphia = new Morphia();
morphia.map(Employee.class);
ds = morphia.createDatastore(mongo, Consts.DatabaseName);
DB db = Mongo.connect(new DBAddress(Consts.DatabaseHost,
Consts.DatabasePort, Consts.DatabaseName));
ds.save(new Employee("Mister", "GOD", null, 0));
// get an employee without a manager
Employee boss = ds.find(Employee.class).field("manager")
.equal(null).get();
Key<Employee> scottsKey = ds.save(new Employee("Scott",
"Hernandez", ds.getKey(boss), 150 * 1000));
// add Scott as an employee of his manager
UpdateResults<Employee> res = ds.update(
boss,
ds.createUpdateOperations(Employee.class).add("underlings",
scottsKey));
// get Scott's boss; the same as the one above.
Employee scottsBoss = ds.find(Employee.class)
.filter("underlings", scottsKey).get();
for (Employee e : ds.find(Employee.class, "manager", boss))
System.out.println(e);
} catch (UnknownHostException e1) {
e1.printStackTrace();
}
}
}
when using the following for the employee class?
@Entity("employees")
class Employee {
public Employee(String firstName, String lastName, Object object, int i) {
this.firstName = firstName;
this.lastName = lastName;
manager = new Key<Employee>(Employee.class, object);
}
// auto-generated, if not set (see ObjectId)
@Id ObjectId id;
// value types are automatically persisted
String firstName, lastName;
// only non-null values are stored
Long salary = null;
// by default fields are @Embedded
Address address;
//references can be saved without automatic loading
Key<Employee> manager;
//refs are stored**, and loaded automatically
@Reference List<Employee> underlings = new ArrayList<Employee>();
// stored in one binary field
//@Serialized EncryptedReviews;
//fields can be renamed
@Property("started") Date startDate;
@Property("left") Date endDate;
//fields can be indexed for better performance
@Indexed boolean active = false;
//fields can loaded, but not saved
@NotSaved String readButNotStored;
//fields can be ignored (no load/save)
@Transient int notStored;
//not @Transient, will be ignored by Serialization/GWT for example.
transient boolean stored = true;
}
However when use the above code, the 'get an employee without a manager' line fails to locate anything and the update operation throws an exception. Any help would be appreciated?
I think it should be Employee boss = ds.find(Employee.class).field("manager").doesNotExist().get();
If I'm not mistaken, entities should have a no-args constructor.
PS: If you want to get started with a complete project quickly, you might want to take a look at https://github.com/xeraa/mongouk2011