Modeling and validating a form with multiple submit

Question

I am trying to figure out the proper way to model and validate a form with multiple form tags and multiple submit buttons using ASP.Net Core 2. What I have is a form where a use

Answer 1

I would break my models into two class and then use a ViewModel instead:

public class SignIn
{
    [Required]
    public string Username { get; set; }
    [Required]
    public string Password { get; set; }
}

public class SignUp
{
    [Required]
    public string FirstName { get; set; }
    [Required]
    public string LastName { get; set; }
    [Required]
    public string CellNumber { get; set; }
}

public class LandingViewModel
{
    public SignIn SignIn { get; set; }
    public SignUp SignUp { get; set; }
}

Then:

@model MyApp.ViewModels.LandingViewModel
SignIn.Username, SignIn.Password, SignUp.FirstName,...