ASP.NET Core email confirmation

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In this video, we will discuss how to implement email confirmation in asp.net core.


Generate email confirmation token in asp.net core

In ASP.NET core generating email confirmation token is straight forward. Use UserManager service GenerateEmailConfirmationTokenAsync() method. This method takes one parameter. The user for whom we want to generate the email confirmation token.

var token = await userManager.GenerateEmailConfirmationTokenAsync(user);

Build the email confirmation link

Once we have the token generated, build the email confirmation link. The user simply clicks this link to confirm his email. This link executes, ConfirmEmail action in Account controller. The user ID and the email confirmation token are passed in the query string. Model binding in ASP.NET core maps the values from the query string parameters to the respective parameters on the ConfirmEmail action.

var confirmationLink = Url.Action("ConfirmEmail", "Account",
    new { userId = user.Id, token = token }, Request.Scheme);

The generated confirmation link would look like the following

https://localhost:44304/Account/ConfirmEmail?userId=987009e3-7f78-445e-8bb8-4400ba886550&token=CfDJ8Hpirs

The last parameter Request.Scheme returns the request protocol such as Http or Https. This parameter is required to generate the full absolute URL. If this parameter is not specified, a relative URL like the following will be generated.

/Account/ConfirmEmail?userId=987009e3-7f78-445e-8bb8-4400ba886550&token=CfDJ8Hpirs

Confirming the email

Use ConfirmEmailAsync() method of the UserManager service to confirm the email. To this method we pass 2 parameters. The user whose email we want to confirm and them email confirmation token. Upon successful email confirmation, this method sets EmailConfirmed column to True in AspNetUsers table.

var result = await userManager.ConfirmEmailAsync(user, token);

Add ASP.NET core default token providers

In ConfigureServices() method of the Startup class, call AddDefaultTokenProviders() method to add the asp.net core default token providers that generate tokens for email confirmation, password reset, two factor authentication etc.

public void ConfigureServices(IServiceCollection services)
{
    services.AddIdentity<ApplicationUser, IdentityRole>(options =>
    {
        options.SignIn.RequireConfirmedEmail = true;
    })
    .AddEntityFrameworkStores<AppDbContext>()
    .AddDefaultTokenProviders();
}

You should add, either the default token providers or your own custom token providers that can generate tokens. Otherwise you would get the following runtime exception.

NotSupportedException: No IUserTwoFactorTokenProvider<TUser> named 'Default' is registered.

Register and ConfirmEmail actions

public class AccountController : Controller

{

    private readonly UserManager<ApplicationUser> userManager;

    private readonly SignInManager<ApplicationUser> signInManager;

    private readonly ILogger<AccountController> logger;

    public AccountController(UserManager<ApplicationUser> userManager,

                                SignInManager<ApplicationUser> signInManager,

                                ILogger<AccountController> logger)

    {

        this.userManager = userManager; this.signInManager = signInManager;

        this.logger = logger;

    }

    [HttpPost]

    [AllowAnonymous]

    public async Task<IActionResult> Register(RegisterViewModel model, string returnUrl)

    {

        if (ModelState.IsValid)

        {

            var user = new ApplicationUser

            {

                UserName = model.Email,

                Email = model.Email,

                City = model.City,

            };

            var result = await userManager.CreateAsync(user, model.Password);

            if (result.Succeeded)

            {

                var token = await userManager.GenerateEmailConfirmationTokenAsync(user);

                var confirmationLink = Url.Action("ConfirmEmail", "Account",

                    new { userId = user.Id, token = token }, Request.Scheme);

                logger.Log(LogLevel.Warning, confirmationLink);

                if (signInManager.IsSignedIn(User) && User.IsInRole("Admin"))

                {

                    return RedirectToAction("ListUsers", "Administration");

                }

                ViewBag.ErrorTitle = "Registration successful";

                ViewBag.ErrorMessage = "Before you can Login, please confirm your " +

                        "email, by clicking on the confirmation link we have emailed you";

                return View("Error");

            }

            foreach (var error in result.Errors)

            {

                ModelState.AddModelError(string.Empty, error.Description);

            }

        }

        return View(model);

    }

    [AllowAnonymous]

    public async Task<IActionResult> ConfirmEmail(string userId, string token)

    {

        if (userId == null || token == null)

        {

            return RedirectToAction("index", "home");

        }

        var user = await userManager.FindByIdAsync(userId);

        if (user == null)

        {

            ViewBag.ErrorMessage = $"The User ID {userId} is invalid";

            return View("NotFound");

        }

        var result = await userManager.ConfirmEmailAsync(user, token);

        if (result.Succeeded)

        {

            return View();

        }

        ViewBag.ErrorTitle = "Email cannot be confirmed";

        return View("Error");

    }

    // rest of the code

}

ConfirmEmail View

<h3>Thank you for confirming your email</h3>

At the moment we are logging the email confirmation link to a file. We will discuss how to send the email confirmation link in an email in our upcoming videos.