How to get and display the email using the Facebook provider in ASP.NET Identity and MVC 5 - asp.net-mvc-5

Question

UPDATE: PLEASE SEE THIS POST: https://stackoverflow.com/a/20379623/687549
Been reading I think almost all questions on SO about external providers and how to get extra info/data/metadata/claims/orwhateveryouwannacallit in particular the email address which many use as the username on modern websites.
So the problem that I was facing was that I wanted to retrieve the email from the Facebook provider with as little code as possible. I thought to myself; the new ASP.NET Identity framework must have this buil-in and can do this with probably just a couple of lines of code. I searched and all I could find was these imensely large chunks of code and I thought to myself: there has got to be another more simpler way. And here it is, as an answer in this questionthread.
I managed to get this working with both Facebook and Google but what I'm concerned about is wheather or not I'm doing this right without any consequenses somewhere else in the code.
For instance: Do you really only need to specify the Scopes.Add("email") for it all to work or why haven't I been able to find more info about this on the interweb?

Answer 1

UPDATE: PLEASE SEE THIS POST: https://stackoverflow.com/a/20379623/687549
Startup.Auth.cs:
var facebookAuthenticationOptions = new FacebookAuthenticationOptions()
{
AppId = "myAppId",
AppSecret = "myAppSecret"
};
facebookAuthenticationOptions.Scope.Add("email");
app.UseFacebookAuthentication(facebookAuthenticationOptions);
AccountController (default mvc 5 template app stuff)
//
// GET: /Account/ExternalLoginCallback
[AllowAnonymous]
public async Task<ActionResult> ExternalLoginCallback(string returnUrl)
{
var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();
if (loginInfo == null)
{
return RedirectToAction("Login");
}
// These next three lines is how I get the email from the stuff that gets returned from the Facebook external provider
var externalIdentity = HttpContext.GetOwinContext().Authentication.GetExternalIdentityAsync(DefaultAuthenticationTypes.ExternalCookie);
var emailClaim = externalIdentity.Result.Claims.FirstOrDefault(c => c.Type == ClaimTypes.Email);
var email = emailClaim.Value;
// Sign in the user with this external login provider if the user already has a login
var user = await UserManager.FindAsync(loginInfo.Login);
if (user != null)
{
await SignInAsync(user, isPersistent: false);
return RedirectToLocal(returnUrl);
}
else
{
// If the user does not have an account, then prompt the user to create an account
ViewBag.ReturnUrl = returnUrl;
ViewBag.LoginProvider = loginInfo.Login.LoginProvider;
// Populate the viewmodel with the email
return View("ExternalLoginConfirmation", new ExternalLoginConfirmationViewModel { UserName = email });
}
}

Answer 2

I have the same problem. You need to edit and add this code to ExternalLoginCallback in the AccountController
var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();
if (loginInfo == null)
{
return RedirectToAction("Login");
}
// added the following lines
if (loginInfo.Login.LoginProvider == "Facebook")
{
var identity = AuthenticationManager.GetExternalIdentity(DefaultAuthenticationTypes.ExternalCookie);
var access_token = identity.FindFirstValue("FacebookAccessToken");
var fb = new FacebookClient(access_token);
dynamic myInfo = fb.Get("/me?fields=email"); // specify the email field
loginInfo.Email = myInfo.email;
}
Note the code dynamic myInfo = fb.Get("/me?fields=email"); this will work for facebook app with version 2.4, but for old version you can write this
dynamic myInfo = fb.Get("email");