com.mongodb.DBRef cannot be cast to org.bson.Document

Question

Hello i'm trying to retrive the roles of user witch are based on another document, I have the referens of this roles in the user document as a list of objects

i get a mistake when this is excuted

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

com.mongodb.DBRef cannot be cast to 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" )));

        }

score 0 · Answer 1 · answered May 25 '18 at 07:40

According to Resolve DBRef into Json you can decode the document to JSON.

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

Then you can parse from the JSON to get the id fields. This might not be the best way to resolve the problem but this is what I'm doing now.

com.mongodb.DBRef cannot be cast to org.bson.Document

1 Answers1