ASP.NET 核心 MVC 绑定包含 2 个域的视图模型 Model

Question

I am working on a simple Web Application with ASP.NET Core 3.1 MVC Framework and Entity Framework Core.

I have 2 domain models: Renter and Address , and a view model RenterViewModel :

public class Renter
{
    public int Id { get; set; }

    [Required]        
    public Type RenterType { get; set;}

    public string CompanyName { get; set;}

    [Required]       
    public string FirstName { get; set; }

    [Required]        
    public string LastName { get; set;}

    [Required]
    public Address Address {get; set;}
    
    public int AddressId {get; set;}
}

public class Address
{
    public Address()
    { }
    public int Id { get; set; }        
    
    [Required]
    public string Street { get; set; }
    
    [Required]
    public string StreetNumber { get; set; }
    
    [Required]
    public string PostalCode { get; set; }
   
    [Required]
    public string City { get; set; }
}

public class RenterViewModel
{
    public RenterViewModel(Renter renter, Address address)
    {
        this.Renter = renter;
        this.Address = address;
    }

    public Renter Renter {get; set;}
    public Address Address {get; set;}       
}

For my index view and details view this works fine.

How can I bind this view model in the controller and validate it, in order to store the Address to the database first and then after it the Renter to the database?

Renter needs the Id of Address because of a foreign key constraint.

My RenterController Create method looks like this:

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create([Bind("Id,RenterType,CompanyName,FirstName,LastName"), prefix="Renter"] Renter renter,
    [Bind("Street, StreetNumber, City, Postalcode"), prefix="Address"] Address address)
{
        if (ModelState.IsValid)
        {
            _context.Add(address);
            renter.Address_Id = address.id;
            _context.Add(renter);
            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index));
        }

        return View(new RenterViewModel(renter, address));
}

The problem is that ModelState.IsValid is always false.

Answer 1

I created sample and table script for you. Please check this url https://gofile.io/d/yorkiv

I use scaffold-dbcontext to generate dbcontext and models.

HomeController.cs

[HttpPost]
    public IActionResult Index(Address address, Renter renter)
    {
        using (var context = new TestDBContext())
        {
            address.Renter.Add(renter);
            context.Add(address);
            context.SaveChanges();
        }
        return View();
    }