How to get identity values from google external provider in ASP.NET Core Web API

Question

    [ApiController]
    [Route("[controller]")]
    public class AuthController : ControllerBase
    {
        private readonly SignInManager _signInManager;

        public AuthController(SignInManager signInManager)
        {
            _signInManager = signInManager ?? throw new ArgumentNullException(nameof(signInManager));
        }

        [HttpGet("token")]
        public ChallengeResult Token()
        {
            var properties = new GoogleChallengeProperties
            {
                RedirectUri = "/auth/retrieve",
                AllowRefresh = true,
            };

            return Challenge(properties, "Google");
        }

        [HttpGet("[action]")]
        public async Task Retrieve()
        {
            var token = await HttpContext.GetTokenAsync("access_token");
            var externalLoginInfoAsync = await _signInManager.GetExternalLoginInfoAsync();
            var identityName = User?.Identity?.Name;
            var authenticateResult = await HttpContext.AuthenticateAsync();
        }
    }

I direct the user to /auth/token, where he is redirected to the Google Oauth Page, if successful, he is redirected to /auth/retrieve, where I expect the user data, but token, externalLoginInfoAsync, identityName, authenticateResult is null

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext(options =>
                options.UseNpgsql(Configuration.GetConnectionString("Default")));
            services.AddIdentity()
                .AddEntityFrameworkStores()
                .AddDefaultTokenProviders();

            services.AddAuthentication()
                .AddCookie()
                .AddGoogle(options =>
                {
                    options.Scope.Add("https://www.googleapis.com/auth/gmail.settings.basic");
                    options.AccessType = "offline";
                    options.SaveTokens = true;
                    options.SignInScheme = IdentityConstants.ExternalScheme;
                    options.Events.OnCreatingTicket = ctx =>
                    {
                        var identityName = ctx.Identity.Name;
                        return Task.CompletedTask;
                    };

                    options.ClientId = "SMTH_VALUE";
                    options.ClientSecret = "SMTH_VALUE";
                });

            services.AddControllers();
        }

I debug the google provider and found the user values in the Events - identityName is not null. How i can get this value in the controller?

user_7062291 · Answer

You could refer the following code to configure Google authentication in Startup.ConfigureServices method:

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddDbContext(options =>
            options.UseSqlServer(
                Configuration.GetConnectionString("DefaultConnection")));
        services.AddDefaultIdentity(options => options.SignIn.RequireConfirmedAccount = true)
            .AddEntityFrameworkStores();

        services.AddAuthentication()
            .AddGoogle(opt =>
            {
                opt.ClientId = "620831551062-rcvu44q4rhr5d8ossu3m0163jqbjdji0.apps.googleusercontent.com";
                opt.ClientSecret = "GXFN0cHBbUlZ6nYLD7a7-cT8";
                opt.SignInScheme = IdentityConstants.ExternalScheme;
            });
        services.AddControllersWithViews();
        services.AddRazorPages();
    }

Then, use the following sample to login using Google and get user information:

[Authorize]
public class AccountController : Controller
{
    private UserManager userManager;
    private SignInManager signInManager;

    public AccountController(UserManager userMgr, SignInManager signinMgr)
    {
        userManager = userMgr;
        signInManager = signinMgr;
    }

    // other methods

    public IActionResult AccessDenied()
    {
        return View();
    }

    [AllowAnonymous]
    public IActionResult GoogleLogin()
    {
        string redirectUrl = Url.Action("GoogleResponse", "Account");
        var properties = signInManager.ConfigureExternalAuthenticationProperties("Google", redirectUrl);
        return new ChallengeResult("Google", properties);
    }

    public IActionResult Login()
    {
        return View();
    }

    [AllowAnonymous]
    public async Task GoogleResponse()
    {
        ExternalLoginInfo info = await signInManager.GetExternalLoginInfoAsync();
        if (info == null)
            return RedirectToAction(nameof(Login));

        var result = await signInManager.ExternalLoginSignInAsync(info.LoginProvider, info.ProviderKey, false);
        string[] userInfo = { info.Principal.FindFirst(ClaimTypes.Name).Value, info.Principal.FindFirst(ClaimTypes.Email).Value };
        if (result.Succeeded)
            return View(userInfo);
        else
        {
            ApplicationUser  user = new ApplicationUser
            {
                Email = info.Principal.FindFirst(ClaimTypes.Email).Value,
                UserName = info.Principal.FindFirst(ClaimTypes.Email).Value
            };

            IdentityResult identResult = await userManager.CreateAsync(user);
            if (identResult.Succeeded)
            {
                identResult = await userManager.AddLoginAsync(user, info);
                if (identResult.Succeeded)
                {
                    await signInManager.SignInAsync(user, false);
                    return View(userInfo);
                }
            }
            return AccessDenied();
        }
    }
}

The result like this:

More detail information, see How to integrate Google login feature in ASP.NET Core Identity and Google external login setup in ASP.NET Core

How to get identity values from google external provider in ASP.NET Core Web API

1 Answers