ASP.NET MVC 5 Core Identity CompanyID foreign key on dbo.AspNetUsers table

Question

I've got an MVC 5 app that uses Core Identity on a SQL server database. On the user registration view, I want to add a foreign key dropdown for the Company that the user is assigned to. It is a required field and a user can only be assigned to one company.

AspNetUsers

Company Table

public class ApplicationUser : IdentityUser
{
    ....
    public int? CompanyID { get; set; }

  //  [ForeignKey("CompanyId")]
  //  public virtual Company UserCompany { get; set; }
}

I have added the CompanyID to the RegisterViewModel under the AccountViewModels.cs

public class RegisterViewModel
{
    ....

    [Required]
    [Display(Name = "Company")]
    public int CompanyID { get; set; }

Then I have added the following to the AccountController:

    using System;
    using System.Globalization;
    using System.Linq;
    using System.Security.Claims;
    using System.Threading.Tasks;
    using System.Web;
    using System.Web.Mvc;
    using Microsoft.AspNet.Identity;
    using Microsoft.AspNet.Identity.Owin;
    using Microsoft.Owin.Security;
    using EMS.Models;

    namespace EMS.Controllers
    {
       // [Authorize]
        public class AccountController : Controller
        {
    private ApplicationSignInManager _signInManager;
    private ApplicationUserManager _userManager;
    private ApplicationDbContext context;
    **private EMSEntities db = new EMSEntities();**

    public AccountController()
    {
        context = new ApplicationDbContext();
    }

    //
    // GET: /Account/Register
    [AllowAnonymous]
    public ActionResult Register()
    {
        **ViewBag.Company = new SelectList(db.Companies.ToList(), "ID", "CompanyName");**
        ViewBag.Name = new SelectList(context.Roles.ToList(), "Name", "Name");
        return View();
    }

    //
    // POST: /Account/Register
    [HttpPost]
    [AllowAnonymous]
    [ValidateAntiForgeryToken]
    public async Task<ActionResult> Register(RegisterViewModel model, ApplicationUser applicationUser)
    {
        if (ModelState.IsValid)
        {
            **ViewBag.Company = new SelectList(db.Companies.ToList(), "ID", "CompanyName", model.CompanyID);**
            var user = new ApplicationUser { UserName = model.Email, Email = model.Email, **CompanyID = model.CompanyID** };
            var result = await UserManager.CreateAsync(user, model.Password);
            if (result.Succeeded)
            {
                await SignInManager.SignInAsync(user, isPersistent: false, rememberBrowser: false);

                // For more information on how to enable account confirmation and password reset please visit https://go.microsoft.com/fwlink/?LinkID=320771
                // Send an email with this link
                // string code = await UserManager.GenerateEmailConfirmationTokenAsync(user.Id);
                // var callbackUrl = Url.Action("ConfirmEmail", "Account", new { userId = user.Id, code = code }, protocol: Request.Url.Scheme);
                // await UserManager.SendEmailAsync(user.Id, "Confirm your account", "Please confirm your account by clicking <a href=\"" + callbackUrl + "\">here</a>");
                await this.UserManager.AddToRoleAsync(user.Id, model.Name);
                return RedirectToAction("Index", "Home");
            }
            AddErrors(result);
        }

        // If we got this far, something failed, redisplay form
        return View(model);
    }

    // New Methods

        [AllowAnonymous]
        [HttpGet]
        public ActionResult RegisterRole()
    {
        ViewBag.Name = new SelectList(context.Roles.ToList(), "Name", "Name");
        ViewBag.UserName = new SelectList(context.Users.ToList(), "UserName", "UserName");
        return View();
    }

And then finally I have added the dropdown to the Register view:

<div class="form-group">
    @Html.Label("Company", new { @class = "col-md-2 control-label" })
    <div class="col-md-10">
        @Html.DropDownList("CompanyID", null, htmlAttributes: new { @class = "form-control" })
    </div>
</div>

When running the app and trying to register a new user, I get the following error:

Register user issue

When trying to login, I get the same error on a different line:

Server Error in '/' Application. The model backing the 'ApplicationDbContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269).

What is the problem?

Answer 1

Thank you Jansen, your answer put me on the right track but did not solve the issue completely. What solved the issue was to add the following to the Global.asax file under Application_Start:

    Database.SetInitializer<ApplicationDbContext>(null);