External login email confirmation in asp.net core

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In this video we will discuss how to confirm the email received from external login providers such as Google, Facebook etc.

When we use external providers like Google or Facebook to login, we receive the user email from these external login provider. We then use this email to create a local user account.


Upon creating a local user account, send email confirmation link. If the email address is not confirmed, do not allow the user to login and display the error - Email not confirmed yet.

On the other hand, if the email address is confirmed, create an external login (AspNetUserLogins) and sign-in the user.

[AllowAnonymous]

public async Task<IActionResult>

ExternalLoginCallback(string returnUrl = null, string remoteError = null)

{

    returnUrl = returnUrl ?? Url.Content("~/");

    LoginViewModel loginViewModel = new LoginViewModel

    {

        ReturnUrl = returnUrl,

        ExternalLogins =

        (await signInManager.GetExternalAuthenticationSchemesAsync()).ToList()

    };

    if (remoteError != null)

    {

        ModelState.AddModelError(string.Empty,

            $"Error from external provider: {remoteError}");

        return View("Login", loginViewModel);

    }

    var info = await signInManager.GetExternalLoginInfoAsync();

    if (info == null)

    {

        ModelState.AddModelError(string.Empty,

            "Error loading external login information.");

        return View("Login", loginViewModel);

    }

    var email = info.Principal.FindFirstValue(ClaimTypes.Email);

    ApplicationUser user = null;

    if (email != null)

    {

        user = await userManager.FindByEmailAsync(email);

        if (user != null && !user.EmailConfirmed)

        {

            ModelState.AddModelError(string.Empty, "Email not confirmed yet");

            return View("Login", loginViewModel);

        }

    }

    var signInResult = await signInManager.ExternalLoginSignInAsync(

                                info.LoginProvider, info.ProviderKey,

                                isPersistent: false, bypassTwoFactor: true);

    if (signInResult.Succeeded)

    {

        return LocalRedirect(returnUrl);

    }

    else

    {

        if (email != null)

        {

            if (user == null)

            {

                user = new ApplicationUser

                {

                    UserName = info.Principal.FindFirstValue(ClaimTypes.Email),

                    Email = info.Principal.FindFirstValue(ClaimTypes.Email)

                };

                await userManager.CreateAsync(user);

                // After a local user account is created, generate and log the

                // email confirmation link

                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);

                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");

            }

            await userManager.AddLoginAsync(user, info);

            await signInManager.SignInAsync(user, isPersistent: false);

            return LocalRedirect(returnUrl);

        }

        ViewBag.ErrorTitle = $"Email claim not received from: {info.LoginProvider}";

        ViewBag.ErrorMessage = "Please contact support on Pragim@PragimTech.com";

        return View("Error");

    }

}

[HttpGet]

[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");

}