marechai/Marechai/Areas/Identity/Pages/Account/ConfirmEmailChange.cshtml.cs

using System.Text;
using System.Threading.Tasks;
using Marechai.Database.Models;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.WebUtilities;

namespace Marechai.Areas.Identity.Pages.Account
{
    [AllowAnonymous]
    public class ConfirmEmailChangeModel : PageModel
    {
        readonly SignInManager<ApplicationUser> _signInManager;
        readonly UserManager<ApplicationUser>   _userManager;

        public ConfirmEmailChangeModel(UserManager<ApplicationUser> userManager,
                                       SignInManager<ApplicationUser> signInManager)
        {
            _userManager   = userManager;
            _signInManager = signInManager;
        }

        [TempData]
        public string StatusMessage { get; set; }

        public async Task<IActionResult> OnGetAsync(string userId, string email, string code)
        {
            if(userId == null ||
               email  == null ||
               code   == null)
            {
                return RedirectToPage("/Index");
            }

            ApplicationUser user = await _userManager.FindByIdAsync(userId);

            if(user == null)
            {
                return NotFound($"Unable to load user with ID '{userId}'.");
            }

            code = Encoding.UTF8.GetString(WebEncoders.Base64UrlDecode(code));
            IdentityResult result = await _userManager.ChangeEmailAsync(user, email, code);

            if(!result.Succeeded)
            {
                StatusMessage = "Error changing email.";

                return Page();
            }

            // In our UI email and user name are one and the same, so when we update the email
            // we need to update the user name.
            IdentityResult setUserNameResult = await _userManager.SetUserNameAsync(user, email);

            if(!setUserNameResult.Succeeded)
            {
                StatusMessage = "Error changing user name.";

                return Page();
            }

            await _signInManager.RefreshSignInAsync(user);
            StatusMessage = "Thank you for confirming your email change.";

            return Page();
        }
    }
}