Junction Table in ASP .NET code first approach

Question

I am creating a junction table between Identity User and a Game table. This table is called UserGame and has two foreign keys (UserID, GameID) and one additional field to store the score.

public class UserGame
{
    [Key]
    public string ApplicationUserID { get; set; }
    public virtual ApplicationUser ApplicationUser { get; set; }

    public int GameID { get; set; }
    public virtual Game Game { get; set; }

    public int Score { get; set; }
}

My confusion lies with creating a new UserGame record. How would I go about doing this and is my approach correct?

Update (This worked):

 [HttpPost]
    public ActionResult SubmitScore(int gameID, int score)
    {
        var playerRecord = new UserGame();

        playerRecord.ApplicationUserID = User.Identity.GetUserId();
        playerRecord.GameID = gameID;
        playerRecord.Score = score;

        return Json(new { success = true });
    }

score 1 · Answer 1 · edited May 23 '17 at 11:54

1

Example of configuring many-to-many relationship in entity framework

Examle of inserting related objects

A couple of tips: I wouldn't declare a primary key in the junction entity as junctions are usually defined by composite keys. Keep in mind that dbcontext.SaveChanges() will look for child entities and save those as well.

edited May 23 '17 at 11:54

Community

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answered Feb 28 '17 at 21:22

NathanS

61
3

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Thanks for your answer, my issue with that example is storing the additional field 'Score'. Should this be in the Game class? – Gareth Quirke Feb 28 '17 at 21:36

dbraillon · Accepted Answer · 2017-02-28T22:55:32.333

1

Both ApplicationUserId and GameId must have a [Key, Column(Order = 0)] attribute. Just set the first to Order 0 and the other to 1.

public class UserGame
{
    [Key, Column(Order = 0)]
    public string ApplicationUserID { get; set; }
    public virtual ApplicationUser ApplicationUser { get; set; }

    [Key, Colum(Order = 1)]
    public int GameID { get; set; }
    public virtual Game Game { get; set; }

    public int Score { get; set; }
}

Then you have the choice to add new record, go through nav property from Game or ApplicationUser or directly with your UserGame class.

edited Feb 28 '17 at 22:55

answered Feb 28 '17 at 22:50

dbraillon

1,742
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Thanks for the help! Still a little lost on adding a new record. I have chosen to go directly with my UserGame class. I created a new UserGame object in my controller. I can assign the gameID and score. I'm wondering if this approach is correct: Retrieve the current user signed in through the User.Identity.GetUserID() and set this as the ApplicationuserID field. – Gareth Quirke Feb 28 '17 at 23:19
Yup, this is a way to go, to add the newly UserGame entity, add it to your context. You should have it as DbSet in your DbContext right ? – dbraillon Mar 01 '17 at 06:36
2

It's working now, could not find this approach anywhere. thanks alot – Gareth Quirke Mar 01 '17 at 12:48

Junction Table in ASP .NET code first approach

2 Answers2