使用ASP.net将子对象另存为ID，而不是MongoDB中的对象

Question

我想将用户的子对象“愿望清单”保存为ID，而不是整个对象，以避免存储重复的对象。 类似于在nodejs中使用'type：mongoose.Schema.types.ObjectId'和'ref：'WishList'进行操作的方式，但是在C＃中使用。

如何在nodejs中完成

let UserSchema = new 
mongoose.Schema({
   Email: String,
   wishlists: [
     {
       type: mongoose.Schema.Types.ObjectId,
       ref: 'WishList'
     }
   ],
   Username: {
     type: String,
     lowercase: true,
     unique: true
   }
 });

在MongoDB中应该如何：

{
    "_id": {
        "$oid": "5b4c40c9470c5e26e0e55359"
    },
    "Username": "gilles",
    "Email": "",
    "Wishlists": [
        {
            "$oid": "5b5ae2914015fb3028582ea6"
        }
    ],  
}

现在如何保存：

{
    "_id": {
        "$oid": "5b4c40c9470c5e26e0e55359"
    },
    "Username": "gilles",
    "Email": "",
    "WishLists": [
        {
            "_id": {
                "$oid": "5b5ae2914015fb3028582ea6"
            },
            "Name": null,
            "Members": null,
            "Wishes": null
        }
    ],
}

ASP.net中的代码：

public class User
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string Id { get; set; }
    public string Username { get; set; }
    public string Email { get; set; }
    public List<WishList> WishLists { get; set; }
 }

 public class WishList
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string Id { get; set; }
    public string Name { get; set; }
    public List<string> Members { get; set; }
    public List<WishItem> Wishes { get; set; }
  }

public class UserRepository : IUserRepository {
    private readonly ObjectContext _context = null;

    public UserRepository(IOptions<Settings> settings)
    {
        _context = new ObjectContext(settings);
    }
    public async Task Add(User user)
    {                         
        await _context.Users.InsertOneAsync(user);
    }
 }

public class ObjectContext {

    public IConfigurationRoot Configuration { get; }
    private IMongoDatabase _database = null;

    public IMongoCollection<User> Users
    {
        get
        {
            return _database.GetCollection<User>("Users");
        }
    }
}