MongoDB receiving ObjectId("0...0")

Question

I am creating a webAPI on chesstournaments. I am writing that in C# (.NET7) using MongoDB Entity Framework. The problem I have is the following: When inserting a tournament with the reference to a user the MongoDB creates ObjectId('000000000000000000000000') instead of the actual reference to the user.

Here is my TournamentModel.cs:

public enum TournamentStatus
{
    Planned,
    Ongoing,
    Finished,
}
public enum TournamentType
{
    Classic,
    Rapid,
    Blitz,
    Bullet
}
[Collection("tournaments")]
public class Tournament
{
    public ObjectId Id { get; set; }
    public ObjectId? UserId { get; set; }
    [Required(ErrorMessage ="Title is required")]
    public string Title { get; set; }        
    public string EventUrl { get; set; }        
    public string County { get; set; }
    [Required(ErrorMessage = "Status is required")]
    public TournamentStatus Status { get; set; }


    [Required(ErrorMessage ="Provide type of tournament")]
    public TournamentType Type {  get; set; }
    [Required(ErrorMessage = "Provide information whether the tournament is FIDE classified")]
    public Boolean IsFide {  get; set; }
    [Required(ErrorMessage ="Provide details for tournament")]
    public TournamentDetails Details { get; set; }        
}

Here is Adding logic in TournamentService.cs:

public void AddTournament(Tournament newTournament)
{                        
    _BCAContextDb.Tournaments.Add(newTournament);
    _BCAContextDb.ChangeTracker.DetectChanges();
    Console.WriteLine(_BCAContextDb.ChangeTracker.DebugView.LongView);
    _BCAContextDb.SaveChanges();
}

And here is my Posting logic in TournamentController.cs:

[HttpPost]
public ActionResult<Tournament> PostTournament(Tournament tournament)
{            
    _tournamentService.AddTournament(tournament);
    return CreatedAtAction(nameof(GetTournamentById), new { id = tournament.Id }, tournament);
}

Now this is my typescript script that's supposed to shove in a new tournament with a reference to a user:

const agent = new https.Agent({
  rejectUnauthorized: false,
});

let tournament = {
  userId:{},
  title: "string",
  eventUrl: "string",
  county: "string",
  status: 0,
  type: 0,
  isFide: true,
  details: {
    startDate: "2024-03-13T18:53:41.465Z",
    endDate: "2024-03-13T18:53:41.465Z",
    place: "string",
    gameTempo: "string",
    referee: "string",
    organizer: "string",
    roundsTotal: 0,
    roundsEnded: 0,
    gameSystem: "string",
  },
};

const grabData = async () => {
  try {
    const response = await axios.get("https://localhost:7001/api/user", { httpsAgent: agent });
    const id = response.data[0].id;
    
    console.log(id);
    return id;
  } catch (error) {
    console.error("Error:", error.message);
    throw error;
  }
};

const main = async () => {
  try {
    const userId = await grabData();
    tournament.userId = userId;
    const tournamentToPush = tournament;
    console.log("Tournament pushed:", tournamentToPush);
    const response = await axios.post("https://localhost:7001/api/tournament", tournamentToPush, { httpsAgent: agent });
    console.log("Tournament created:", response.data);
  } catch (error) {
    console.error("Error:", error.message);
  }
};

main();

Now the part that I don't understand is that console.log("Tournament pushed:", tournamentToPush); logs out properly:

Tournament pushed: {
  userId: {
    timestamp: 1710351938,
    machine: 1666371,
    pid: -758,
    increment: 3116068,
    creationTime: '2024-03-13T17:45:38Z'
  },
  title: 'string',
  eventUrl: 'string',
  county: 'string',
  status: 0,
  type: 0,
  isFide: true,
  details: {...}
}

However the document in database looks like this:

and I have no clue what did I do wrong. All answers and tips are appreciated.

Answer 1

You need to specify an id field for the model to have it auto populate as a new Object Id.

This can be done using the following attribute:

BsonIdAttribute

IE:

[BsonId] public string Id