Morphia（MongoDB）Datastore“get”返回null

Question

所以我开始和Morphia一起工作，我遇到了一个奇怪的问题。

@Entity("movies")
@Indexes(@Index(value = "Name", fields = @Field("Name")))
@Converters(LocalDateConverter.class)
public class MovieDetails implements Serializable
{
    @Id
    public String Id;
    public String Name;
    public String Description;
    public String ImageName;
    public LocalDate ReleaseDate;
    public String Director;
    public int Duration;
    public String Genres;
    public String Actors;

    public MovieDetails()
    {

    }

    public MovieDetails(String id, String name, String description, String imageName, String director, String actors, LocalDate releaseDate, String genres, int duration)
    {
        this (name, description, imageName, director, actors, releaseDate, genres, duration);
        Id = id;
    }

    public MovieDetails(String name, String description, String imageName, String director, String actors, LocalDate releaseDate, String genres, int duration)
    {
        Name = name;
        Description = description;
        ImageName = imageName;
        Director = director;
        Actors = actors;
        ReleaseDate = releaseDate;
        Genres = genres;
        Duration = duration;
    }
}

final Morphia morphia = new Morphia();

// tell Morphia where to find your classes
// can be called multiple times with different packages or classes
morphia.mapPackage("nimrodpasha.cinema.objects");

// create the Datastore connecting to the default port on the local host
final Datastore datastore =
        morphia.createDatastore(SingleMongoClient.getInstance().getClient(),
                                Constants.DB.TICKET_DATABASE);
datastore.ensureIndexes();

    //region new movie
    MovieDetails movie = new MovieDetails("The Mask", "Stanley Ipkiss (Jim Carrey) is a bank clerk that is an incredibly nice man. Unfortunately," +
            " he is too nice for his own good and is a pushover when it comes to confrontations. After one of the worst days of his life, he finds a mask that depicts Loki, " +
            "the Norse night god of mischief. Now, when he puts it on, he becomes his inner, self: a cartoon romantic wild man. However, a small time crime boss, Dorian Tyrel (Peter Greene), " +
            "comes across this character dubbed The Mask by the media. After Ipkiss's alter ego indirectly kills his friend in crime," +
            " Tyrel now wants this green-faced goon destroyed.",
                                          "MASK.jpg", "Chuck Russell", "Jim Carrey as Stanley Ipkiss/The Mask,Cameron Diaz as Tina Carlyle,Amy Yasbeck as Peggy Brandt,Joely Fisher as Maggie", new LocalDate(1994, 2, 1), "Action,Comedy,CrimeAction,Family,Fantasy", 88);
    //endregion

// Clearing the db first
datastore.delete(datastore.createQuery(MovieDetails.class));

// Saving a new entity and getting the result saved id
String id = (String) datastore.save(movie).getId();

// This returns as null
MovieDetails movieRetrieved = datastore.get(MovieDetails.class, id);

// This returns with one item
List<MovieDetails> allMovies = datastore.createQuery(MovieDetails.class).asList();

get（moviedetails.class,id）

我得到null

当我使用：

Answer 1

我会将I'd字段从String更改为BSON ObjectId字段，MongoDB将在保存时自动分配该字段。如果然后使用ObjectId作为参数进行get调用，它应该可以工作。强烈建议在Mongo中使用ObjectId作为ID字段。

我猜Morphia正试图将一个ObjectId添加到字符串Id字段中，但在某个地方有一个小bug。我将尝试调用datastore.get(example.class,new ObjectId(id))。