3

私はUser

public class User {
    private String name;
    private String email;

    public User () {  }

    public User(String name) {
        this.name = name;
    }

    public User(String name, String email) {
        this(name);
        this.email = email;
    }
    // getters and setters
}

また、私は単純なPOJOを持っていますComment

public class Comment {
    private String comment;
    private Date date;
    private String author;

    public Comment() { }

    public Comment(String comment, Date date, String author) {
        this.comment = comment;
        this.date = date;
        this.author = author;
    }
    // getters and setters
}

次のように、彼に関する何らかのコメントを付けて、新しいユーザーをコレクションに挿入する方法:

public static void main(String[] args) {
    MongoClient client = new MongoClient();
    MongoDatabase db = client.getDatabase("example");
    MongoCollection<Document> collection = db.getCollection("object_arrays");

    collection.drop();

    List<Comment> reviews = new ArrayList<Comment>(){{
        add(new Comment("cool guy", new Date(), "John Doe"));
        add(new Comment("best joker", new Date(), "Vas Negas"));
        add(new Comment("very stupid but very funny man", new Date(), "Bill Murphy"));
    }};
    Document user = new Document();
    user.append("user", new User("0xFF", "email@email.com"))
            .append("reviews", reviews)
            .append("createDate", new Date());
    collection.insertOne(user);
}

残念ながら、例外があります:

    Exception in thread "main" org.bson.codecs.configuration.CodecConfigurationException: Can't find a codec for class com.mongodb.course.com.mongodb.course.model.User.
    at org.bson.codecs.configuration.CodecCache.getOrThrow(CodecCache.java:46)
    at org.bson.codecs.configuration.ProvidersCodecRegistry.get(ProvidersCodecRegistry.java:63)
    at org.bson.codecs.configuration.ChildCodecRegistry.get(ChildCodecRegistry.java:51)
    at org.bson.codecs.DocumentCodec.writeValue(DocumentCodec.java:174)
    at org.bson.codecs.DocumentCodec.writeMap(DocumentCodec.java:189)
    at org.bson.codecs.DocumentCodec.encode(DocumentCodec.java:131)
    at org.bson.codecs.DocumentCodec.encode(DocumentCodec.java:45)
    at org.bson.codecs.BsonDocumentWrapperCodec.encode(BsonDocumentWrapperCodec.java:63)
    at org.bson.codecs.BsonDocumentWrapperCodec.encode(BsonDocumentWrapperCodec.java:29)
    at com.mongodb.connection.InsertCommandMessage.writeTheWrites(InsertCommandMessage.java:101)
    at com.mongodb.connection.InsertCommandMessage.writeTheWrites(InsertCommandMessage.java:43)
    at com.mongodb.connection.BaseWriteCommandMessage.encodeMessageBodyWithMetadata(BaseWriteCommandMessage.java:129)
    at com.mongodb.connection.RequestMessage.encodeWithMetadata(RequestMessage.java:160)
    at com.mongodb.connection.WriteCommandProtocol.sendMessage(WriteCommandProtocol.java:212)
    at com.mongodb.connection.WriteCommandProtocol.execute(WriteCommandProtocol.java:101)
    at com.mongodb.connection.InsertCommandProtocol.execute(InsertCommandProtocol.java:67)
    at com.mongodb.connection.InsertCommandProtocol.execute(InsertCommandProtocol.java:37)
    at com.mongodb.connection.DefaultServer$DefaultServerProtocolExecutor.execute(DefaultServer.java:159)
    at com.mongodb.connection.DefaultServerConnection.executeProtocol(DefaultServerConnection.java:286)
    at com.mongodb.connection.DefaultServerConnection.insertCommand(DefaultServerConnection.java:115)
    at com.mongodb.operation.MixedBulkWriteOperation$Run$2.executeWriteCommandProtocol(MixedBulkWriteOperation.java:455)
    at com.mongodb.operation.MixedBulkWriteOperation$Run$RunExecutor.execute(MixedBulkWriteOperation.java:646)
    at com.mongodb.operation.MixedBulkWriteOperation$Run.execute(MixedBulkWriteOperation.java:401)
    at com.mongodb.operation.MixedBulkWriteOperation$1.call(MixedBulkWriteOperation.java:179)
    at com.mongodb.operation.MixedBulkWriteOperation$1.call(MixedBulkWriteOperation.java:168)
    at com.mongodb.operation.OperationHelper.withConnectionSource(OperationHelper.java:230)
    at com.mongodb.operation.OperationHelper.withConnection(OperationHelper.java:221)
    at com.mongodb.operation.MixedBulkWriteOperation.execute(MixedBulkWriteOperation.java:168)
    at com.mongodb.operation.MixedBulkWriteOperation.execute(MixedBulkWriteOperation.java:74)
    at com.mongodb.Mongo.execute(Mongo.java:781)
    at com.mongodb.Mongo$2.execute(Mongo.java:764)
    at com.mongodb.MongoCollectionImpl.executeSingleWriteRequest(MongoCollectionImpl.java:515)
    at com.mongodb.MongoCollectionImpl.insertOne(MongoCollectionImpl.java:306)
    at com.mongodb.MongoCollectionImpl.insertOne(MongoCollectionImpl.java:297)
    at com.mongodb.course.week3.ArrayListWithObject.main(ArrayListWithObject.java:34)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

MongoDB の Java ドライバーがオブジェクトを変換できず、Document何らかのコンバーターが必要であることを理解しています。Codec、CodecRegistryおよびCodecProviderインターフェースについても知っています。ところで、オブジェクトを mongo ドキュメントに変換する簡単な方法はありますか? どうすればそれを行うことができるか例を示してもらえますか? ありがとうございました。

4

2 に答える 2

1

このような Java オブジェクトを操作したい場合は、Morphiaが最適です。あなたが試みているような任意のJavaクラスをサポートするために現在行われている作業がありますが、まだ完了していません.

于 2016-04-04T12:55:55.270 に答える