更新现有孩子而不是添加新孩子

Question

I am creating a Web app with ASP.NET Core (MVC). Database is SQL Server. Code First design. I am new to EF.

I have defined Visitor model, a Checkin and a Checkout model with a relationship of 1:1 for visitor/checkin and 1:1 for visitor/checkout. The idea of the app is when a new visitor is created, a new check-in and new check-out records are created and children of the visitor record.

My models are as follows (I am using the ForeignKey data annotation to define the one-to-one relationship between visitor and checkin and between visitor and checkout):

public class Visitor
{
    [Key]
    public int Id { get; set; }

    [DisplayName("Visitor First Name")]
    [Required]
    public string FirstName { get; set; }

    [DisplayName("Visitor Last Name")]
    [Required]
    public string LastName { get; set; }

    public CheckIn CheckIn { get; set; }
    public CheckOut CheckOut { get; set; }
}

public class CheckIn
{
    [ForeignKey("Visitor")]
    public int Id { get; set; }

    [DisplayName("Time In")]
    [DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:g}")]
    public DateTime Time { get; set; }

    public Visitor Visitor { get; set; }
}

public class CheckOut
{
    [ForeignKey("Visitor")]
    public int Id { get; set; }

    [DisplayName("Time Out")]
    [DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:g}")]
    public DateTime? Time { get; set; }

    public Visitor Visitor { get; set; }
}

I have a POST method in my controller that should add a new visitor in the database as well as a new checkin and checkout record as children of the visitor record.

However, I am running into issues where the checkin record is not added to the database: instead an existing checkin record in the DB is updated so its primary key is the key (ID) of the new visitor record. The new visitor record is created OK. Also the new checkout record is also created correctly and as a child of the new visitor record. Here is the code of the POST method from my controller (removed some code not relevant to this question) (also using a viewmodel to pass data from the view to the controller):

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> ConfirmSignin(SignVM obj)
    {
        if (ModelState.IsValid)
        {
            var visitor = new Visitor();
            var checkin = new CheckIn();
            var checkout = new CheckOut();

            checkin = obj.CheckIn;
            checkout = obj.CheckOut;
            visitor = obj.Visitor;
            visitor.CheckIn = checkin;
            visitor.CheckOut = checkout;

            _context.Add(visitor);
            _context.Add(checkin);
            _context.Add(checkout);

            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index),"Home",new { LocationId = obj.Visitor.LocationId });
        }
        return View(obj);
    }

Visitors are created successfully in the database:

Checkouts are also created successfully in the database:

You will notice that the ID of the checkouts records match the ID of the parent record Visitor - so this part seems to be working fine.

But the checkin record is not added when a new visitor is added in the database:

A new checkin record should have been added in the database when I added visitor ID=6 - instead EF updated an existing checkin record and updated its primary key from 5 (previous visitor) to 6 (new visitor).

I assume I am doing something wrong in the controller code. Any suggestion?

UPDATE - 4/28/2021: Below is the code for the corresponding GET method:

[HttpGet]
public IActionResult ConfirmSignin()
{
        SignVM signVM = new();

        if (TempData["NewSignIn"] is string s)
        {
            signVM = JsonConvert.DeserializeObject<SignVM>(s);
        }

        ViewData["LocationName"] = new SelectList(_context.Locations, "Id", "Name", signVM.Visitor.LocationId);

        return View(signVM);
}

Below is the updated full code of the POST method:

 [HttpPost]
 [ValidateAntiForgeryToken]
 public async Task<IActionResult> ConfirmSignin(SignVM obj)
 {
       if (ModelState.IsValid)
       {
           var escort = new Escort();

           escort = await _context.Escorts
                    .Include(c => c.CheckIn)
                    .FirstOrDefaultAsync(m => m.EmployeeId == obj.Escort.EmployeeId);
                    
           if (escort == null)
           {
               escort = obj.Escort;
               _context.Add(escort);
               await _context.SaveChangesAsync();
           }

           var visitor = obj.Visitor;
           var checkin = obj.CheckIn;
           var checkout = obj.CheckOut;

           visitor.CheckIn = checkin;
           visitor.CheckOut = checkout;

           escort.CheckIn = new List<CheckIn>();
           escort.CheckOut = new List<CheckOut>();
           escort.CheckIn.Add(checkin);
           escort.CheckOut.Add(checkout);
           _context.Add(visitor);


           await _context.SaveChangesAsync();
           return RedirectToAction(nameof(Index),"Home",new { LocationId = obj.Visitor.LocationId });
       }
       return View(obj);
}

And this is the code of the corresponding view:

@model VisitorLog.Models.ViewModels.SignVM

@{
    ViewData["Title"] = "Sign In";
}


<div class="row justify-content-center mt-3">
    <div class="col-md-4">
        <div class="h4 text-center">Confirm Sign In</div>
        <hr />
        <form asp-action="ConfirmSignin">
            <div class="form-group">
                <label asp-for="Visitor.LocationId" class="control-label"></label>
                <select asp-for="Visitor.LocationId" class="form-control" disabled asp-items="ViewBag.LocationName"></select>
            </div>
            <div class="form-group">
                <label asp-for="Visitor.FullName" class="control-label"></label>
                <input asp-for="Visitor.FullName" class="form-control" readonly value="@Model.Visitor.FullName" />
            </div>
            <div class="form-group">
                <label asp-for="Visitor.Company" class="control-label"></label>
                <input asp-for="Visitor.Company" class="form-control" readonly value="@Model.Visitor.Company" />
            </div>
            <div class="form-group">
                <label asp-for="Escort.EmployeeId" class="control-label"></label>
                <input asp-for="Escort.EmployeeId" class="form-control" readonly value="@Model.Escort.EmployeeId" />
            </div>
            <div class="form-group">
                <label asp-for="Escort.FullName" class="control-label"></label>
                <input asp-for="Escort.FullName" class="form-control" readonly value="@Model.Escort.FullName" />
            </div>
            <div class="form-group">
                <label asp-for="CheckIn.Time" class="control-label"></label>
                <input asp-for="CheckIn.Time" class="form-control" readonly type="text" value="@Model.CheckIn.Time.ToString("g")" />
            </div>
            <div class="form-group">
                <label asp-for="CheckOut.ExpectedTime" class="control-label"></label>
                <input asp-for="CheckOut.ExpectedTime" class="form-control" readonly type="text" value="@Model.CheckOut.ExpectedTime.ToString("g")" />
            </div>
            <div class="form-group">
                <input asp-for="Visitor.LocationId" class="form-control" hidden value="@Model.Visitor.LocationId" />
            </div>
            <div class="form-group">
                <input asp-for="Visitor.FirstName" class="form-control" hidden value="@Model.Visitor.FirstName" />
            </div>
            <div class="form-group">
                <input asp-for="Visitor.LastName" class="form-control" hidden value="@Model.Visitor.LastName" />
            </div>
            <div class="form-group">
                <input asp-for="Visitor.SignedIn" class="form-control" hidden value="@Model.Visitor.SignedIn" />
            </div>

            <div class="form-group">
                <input asp-for="Escort.FirstName" class="form-control" hidden value="@Model.Escort.FirstName" />
            </div>
            <div class="form-group">
                <input asp-for="Escort.LastName" class="form-control" hidden value="@Model.Escort.LastName" />
            </div>
            <div class="form-group">
                <input asp-for="Escort.EmailAddress" class="form-control" hidden value="@Model.Escort.EmailAddress" />
            </div>
            <div class="form-group">
                <input asp-for="Escort.Phone" class="form-control" hidden value="@Model.Escort.Phone" />
            </div>
            <div class="form-group text-center mt-4">
                <input type="submit" class="btn btn-primary col-5" value="Confirm" />
                <a class="btn btn-danger col-5 offset-1" asp-controller="Visitors" asp-action="SignIn" asp-route-LocationId=@Context.Request.Query["LocationId"]>Back</a>
            </div>
        </form>
    </div>
</div>


@section Scripts {
    @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

Answer 1

you have to fix your classes:

public class CheckIn
    {
        [Key]
        public int Id { get; set; }

        [DisplayName("Time In")]
        [DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:g}")]
        public DateTime Time { get; set; }

          public int VisitorId { get; set; }

        [ForeignKey("VisitorId")]
        public virtual Visitor Visitor { get; set; }

    }

    public class CheckOut
    {
        [Key]
        public int Id { get; set; }


        [DisplayName("Time Out")]
        [DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:g}")]
        public DateTime? Time { get; set; }

        public int VisitorId { get; set; }

        [ForeignKey("VisitorId")]
        public virtual Visitor Visitor { get; set; }

    }

and fix your code

.....

  var visitor = obj.Visitor;
   var checkin = obj.CheckIn;
   var checkout = obj.CheckOut;

     visitor.CheckIn = checkin;
      visitor.CheckOut = checkout;

  _context.Add(visitor);

 await _context.SaveChangesAsync();

.....

But IMHO you don't need 2 tables - checkin and checkout. It would be enough just one CheckInOut with IsCheckOut bool flag

public class CheckInOut
    {
        [Key]
        public int Id { get; set; }

        public bool IsCheckOut { get; set; }


        [DisplayName("Time")]
        [DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:g}")]
        public DateTime Time { get; set; }

          public int VisitorId { get; set; }

        [ForeignKey("VisitorId")]
        public virtual Visitor Visitor { get; set; }

    }
            

Answer 2

I resolved the issue by updating the POST method as follows:

Changed:

escort = await _context.Escorts
         .Include(c => c.CheckIn)
         .FirstOrDefaultAsync(m => m.EmployeeId == obj.Escort.EmployeeId); 

To:

escort = await _context.Escorts
         .FirstOrDefaultAsync(m => m.EmployeeId == obj.Escort.EmployeeId);