UUID as _id in mongodb - database

Question

I've found multiple sites saying using UUID is possible, but not how. I've tried to simply have a "_id" property that is a UUID, but when I use postman to get the object the "_id" field says null.
Here is a screenshot.
I've made sure mongodb knows UUID by specifying it in the settings:
`
import com.mongodb.ConnectionString;
import com.mongodb.MongoClientSettings;
import com.mongodb.client.*;
import static com.mongodb.client.model.Filters.eq;
import com.mongodb.client.model.FindOneAndReplaceOptions;
import com.mongodb.client.model.ReturnDocument;
import de.tudo.ls14.aqua.smarthome.model.Device;
import de.tudo.ls14.aqua.smarthome.model.Household;
import de.tudo.ls14.aqua.smarthome.model.User;
import org.bson.Document;
import org.bson.UuidRepresentation;
import org.bson.codecs.configuration.CodecRegistry;
import org.bson.codecs.pojo.PojoCodecProvider;
import org.springframework.stereotype.Repository;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
import java.util.logging.Level;
import java.util.logging.Logger;
import static org.bson.codecs.configuration.CodecRegistries.fromProviders;
import static org.bson.codecs.configuration.CodecRegistries.fromRegistries;
#Repository("Mongodao")
public class MongoDao {
final MongoClient mongoClient;
final MongoDatabase mongoDatabase;
final MongoCollection<User> userCollection;
final MongoCollection<Household> householdCollection;
final MongoCollection<Device> deviceCollection;
public MongoDao() {
String password = System.getProperty("password");//Passwort aus den VM options
Logger.getLogger("org.mongodb.driver").setLevel(Level.ALL);
ConnectionString connectionString = new ConnectionString("someConnectionString");
CodecRegistry pojoCodecRegistry = fromProviders(PojoCodecProvider.builder().automatic(true).build());
CodecRegistry codecRegistry = fromRegistries(MongoClientSettings.getDefaultCodecRegistry(), pojoCodecRegistry);
MongoClientSettings clientSettings = MongoClientSettings.builder()
.uuidRepresentation(UuidRepresentation.STANDARD)
.applyConnectionString(connectionString)
.codecRegistry(codecRegistry)
.build();
mongoClient = MongoClients.create(clientSettings);
mongoDatabase = mongoClient.getDatabase("ProjektDB");
userCollection = mongoDatabase.getCollection("userCollection", User.class);
householdCollection = mongoDatabase.getCollection("householdCollection", Household.class);
deviceCollection = mongoDatabase.getCollection("deviceCollection", Device.class);
}
public User getUserById(UUID id) {
return userCollection.find(eq("id", id)).first();
}
public Household getHouseholdById(UUID id) {
return householdCollection.find(eq("id", id)).first();
}
public Device getDeviceById(UUID id) {
return deviceCollection.find(eq("id", id)).first();
}
public int addHousehold(Household household) {
householdCollection.insertOne(household);
return 1;
}
public int addUser(User user) {
userCollection.insertOne(user);
System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> added:"+user.toString());
return 1;
}
public int addDevice(Device device) {
deviceCollection.insertOne(device);
return 1;
}
public User updateUserById(User user) {
Document filterByUserId = new Document("_id", user.get_id());
FindOneAndReplaceOptions returnDocAfterReplace = new FindOneAndReplaceOptions().returnDocument(ReturnDocument.AFTER);
return userCollection.findOneAndReplace(filterByUserId, user, returnDocAfterReplace);
}
//nur zum testen
public List<User> getAllUsers() {
MongoCursor<User> cursor = userCollection.find().iterator();
List<User> userList = new ArrayList<>();
try{
while(cursor.hasNext()){
userList.add(cursor.next());
}
} finally {
cursor.close();
}
return userList;
}
}
`
Funny enough when i check with ATLAS it even says the _id field is an objectid as seen here.
I've printed my object out and it is clear that the _id field is UUID as seen here.
For the sake of it here is also shown that my pojo certainly uses UUID for the _id field. I'm out of ideas.
Do I have to specify things differently?

Answer 1

I had to add a #BsonProperty("_id") annotation to the UUID property in the POJO because it was just private UUID id = IdUtils.newId(); Not _id.
To query using the java driver:
import org.bson.Document;
public User findUserById(final UUID id){
return collection.find(new Document("_id", id)).first();
}