ASP.NET Core 6 MVC - EF Core 6 - model is not validating correctly-CodePudding

I'm currently trying to start a new project with ASP.NET Core 6 MVC and Entity Framework Core 6 and npgsql.

When I try to add one entity which has a foreign identity the ModelState.IsValid keeps returning false - as the model doesn't expand the foreign entity.

Basically I followed the official documentation at:

So my classes look like:

namespace PV.Models
{
    public class Fakultaet
    {
        [Key]
        public int FakultaetID { get; set; }
        [Required]
        public string FakuName { get; set; }
    }

    public class Studiengang
    {
        [Key]
        public int StudiengangID { get; set; }
        [Required]
        public string StudiengangName { get; set;}
        [Required,ForeignKey("Fakultaet")]
        public int FakultaetID { get; set; }
        
        public Fakultaet Fakultaet { get; set; }
    }
}

Partial view:

@model PV.Models.Studiengang
<tr>
         <td>
            <div asp-validation-summary="ModelOnly" ></div>
            <input asp-for="StudiengangName"  />
            <span asp-validation-for="StudiengangName" ></span>
        </td>
        <td>
            <select asp-for="FakultaetID"  asp-items="ViewBag.FakultaetId">
                <option disabled="disabled" selected="selected" value="0">Bitte wählen...</option>
            </select>
            <span asp-validation-for="FakultaetID" ></span>
        </td>
        <td>
            <input type="submit" value="Speichern"  id="btn-addinline-submit" />
            <input type="reset" onClick="location.reload()"  id="btn-addinline-abort" value="Abbrechen" />
        </td>
</tr>

Controller:

namespace PV.Controllers
{
    public class StudiengangController : Controller
    {
        private readonly PraktikumsKontext _context;

        public StudiengangController(PraktikumsKontext ctx)
        {
            _context = ctx;
        }
       
        // --- snip ---

        // GET: Student/Add
        public IActionResult AddStudiengangInline()
        {
            ViewBag.FakultaetId = new SelectList(_context.Fakultaeten.AsNoTracking(), "FakultaetID", "FakuName");
            return PartialView();
        }

        // POST: Student/Add
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> AddStudiengangInline([Bind("StudiengangName, FakultaetID")] Studiengang studiengang )
        {
            if (ModelState.IsValid)
            {
                _context.Add(studiengang);
                await _context.SaveChangesAsync();
                return RedirectToAction("Index");
            }

            ViewData["FakultaetId"] = new SelectList(_context.Fakultaeten, "FakultaetID", "FakuName", studiengang.FakultaetID);

            return PartialView(studiengang);
        }
    }
}

When I now fill out my form and POST StudiengangName=Test1234;FakultaetID=1 (with an existing Fakultaet with ID = 1 of course) my model does look like this:

StudiengangID = 0
StudiengangName = "Test1234"
Fakultaet = null
FakultaetID = 1

Therefore the ModelState.IsValid returns false as Fakultaet is null.

Here I'd assume that EF Core 6 does its magic and resolves the entity I'm referencing.

If I add the following snippet before checking if the model is valid, everything seems to work:

studiengang.Fakultaet =
                _context.Fakultaeten.SingleOrDefault(stg => stg.FakultaetID == studiengang.FakultaetID);
            ModelState.ClearValidationState(nameof(Fakultaet));
            TryValidateModel(studiengang);

But this seems to be a dirty workaround as it was not necessary in .NET Core 3.1 with almost the same setup.

Does anyone have an idea what I'm missing?

CodePudding user response：

you have to add form with validation and antiforgery to your view

@model PV.Models.Studiengang

<form method="post"  asp-controller="Studiengang" asp-action="AddStudiengangInline" >

@Html.AntiForgeryToken()

@Html.ValidationSummary(false, "", new { @class = "text-danger" })


<tr>
         ,,,,,

     <td>
 <input type="submit" value="Speichern"  id="btn-addinline-submit" />
          ...
        </td>
</tr>
                    
</form>

It is better to add a list of DDL items to viewModel

 public class Studiengang
    {
       ....
        public int FakultaetID { get; set; }
        
        public Fakultaet Fakultaet { get; set; }

        [NotMapped]
        public List<SelectListItem> FakultaetItems { get; set; }
    }

action

public IActionResult AddStudiengangInline()
{
var model= new Studiengang { FakultaetItems = new _context.Fakultaeten
.Select (i=> new SelectListItem { Value=i.FakultaetID, Text=i.FakuName}).ToList();
return PartialView(model);
}

IMHO remove Bind from post action

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> AddStudiengangInline(Studiengang studiengang )

and finaly a select control

 <select asp-for="FakultaetID"  asp-items="@Model.FakultaetItems"> </select>

CodePudding user response：

As this document said:

Beginning with .NET 6, new projects include the <Nullable>enable</Nullable> element in the project file. Once the feature is turned on, existing reference variable declarations become non-nullable reference types.

In .NET 6 the non-nullable property must be required, otherwise the ModelState will be invalid.

To achieve your requirement, you can remove <Nullable>enable</Nullable> from your project file.

The second way, you can initialize the model like below:

public class Studiengang
{
    [Key]
    public int StudiengangID { get; set; }
    [Required]
    public string StudiengangName { get; set;}
    [Required,ForeignKey("Fakultaet")]
    public int FakultaetID { get; set; }
    
    public Fakultaet Fakultaet { get; set; } = new Fakultaet();
}

The third way, you can add ? to allow nullable:

public class Studiengang
{
    [Key]
    public int StudiengangID { get; set; }
    [Required]
    public string StudiengangName { get; set;}
    [Required,ForeignKey("Fakultaet")]
    public int FakultaetID { get; set; }
    
    public Fakultaet? Fakultaet { get; set; }
}

The last way is like what you did to remove the key in model validation.

CodePudding user response：

Try using an InputModel with only the StudentId, StudentName, FacultyId and a collection of all faculties, populated from the database, as properties and pass that model to the dbContext.