com.mongodb.dbref不能施放到org.bson.document

Question

您好，我正在尝试检验用户女巫的角色是基于另一个文档，我将此角色的参考文献作为对象列表

我会出现一个错误

List<Document> listRoles = (List<Document>) document.get("listRole");

com.mongodb.dbref不能被施加到org.bson.document

{
    "_id" : ObjectId("5a8bf269e1147736b4a7d06c"),
    "_class" : "fr.anasys.testsecuritymongodb.models.User",
    "username" : "hamou",
    "password" : "amroun",
    "actived" : true,
    "listRole" : [ 
        {
            "$ref" : "role",
            "$id" : ObjectId("5a8bf269e1147736b4a7d06a")
        }, 
        {
            "$ref" : "role",
            "$id" : ObjectId("5a8bf269e1147736b4a7d06b")
        }
    ]
}

    MongoDatabase database = mongoClient.getDatabase("rdproject2");
    MongoCollection<Document> collection = database.getCollection("User");
    Document document = collection.find(Filters.eq("username",email)).first();
    if(document!=null) {
        String username = document.getString("username");
        String password = document.getString("password");
        boolean actived = document.getBoolean("actived");
        List<Document> listRoles = (List<Document>) document.get("listRole");
        List<RefId> listRefIds = new ArrayList<>();
        for (Document refId :listRoles ) {
           listRefIds.add(new RefId(refId.getString("ref"),refId.getString("id" )));
        }

Answer 1

根据resolve dbRef的json，您可以将文档解码为JSON。

CodecRegistry codecRegistry = CodecRegistries.fromRegistries(MongoClient.getDefaultCodecRegistry());
final DocumentCodec codec = new DocumentCodec(codecRegistry, new BsonTypeClassMap());
--------
String docJson = document.toJson(codec);

然后，您可以从JSON解析以获取ID字段。这可能不是解决问题的最佳方法，但这就是我现在正在做的事情。