How to use Google sign-in without using default UI but using ASP Identity - blazor-server-side

Question

I'm trying to implement custom UI for signing in and Login users with social media providers like Google. I don't want to use at all the Identity UI as it does not fit my needs. So, my UI has a "Sign-in with Google" button, that invokes an ApiController method
[Route("/[controller]")]
[ApiController]
public class AuthController : ControllerBase
{
[HttpGet("google-login")]
public async Task<ActionResult> GoogleLogin(string returnUrl = null, string remoteError = null)
{
var properties = new AuthenticationProperties
{
RedirectUri = "/"
};
return await Task.FromResult(Challenge(properties, GoogleDefaults.AuthenticationScheme));
}
}
This navigates to Google and I am able to sign in without trouble. After return, I can see User data inside OnCreatingTicket
.AddGoogle(options =>
{
...
options.Events.OnCreatingTicket = context =>
{
var Id = context.User.GetProperty("id").GetString();
var email = context.User.GetProperty("email").GetString();
var name = context.User.GetProperty("name").GetString();
// TODO: SignIn user
//...
}
}
but of course, ASP User Identity has no clue about the user.
The question is how to sign the user with the Identity and if it is not already part of the DB to create an account accordingly?
Extended listing of Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
//...
services.AddResponseCaching();
services.AddRazorPages();
services.AddServerSideBlazor();
services.AddHttpContextAccessor();
//...
services.AddDbContextFactory<ApplicationDbContext>(options =>
options.UseSqlite(Configuration.GetConnectionString("DefaultConnection")));
services.AddIdentityCore<ApplicationUser>(options => options.SignIn.RequireConfirmedAccount = false)
.AddEntityFrameworkStores<ApplicationDbContext>()
.AddDefaultTokenProviders();
services.AddIdentity<ApplicationUser, IdentityRole>()
.AddEntityFrameworkStores<ApplicationDbContext>();
services.AddDatabaseDeveloperPageExceptionFilter();
services.AddAuthentication(options =>
{
options.DefaultAuthenticateScheme = IdentityConstants.ApplicationScheme;
options.DefaultChallengeScheme = IdentityConstants.ApplicationScheme;
options.DefaultSignInScheme = IdentityConstants.ExternalScheme;
})
.AddGoogle(options =>
{
options.ClientId = Configuration["Authentication:Google:ClientId"];
options.ClientSecret = Configuration["Authentication:Google:ClientSecret"];
options.Scope.Add("profile");
options.ClaimActions.MapJsonKey(ClaimTypes.NameIdentifier, "sub", "string");
options.Events.OnCreatingTicket = context =>
{
var Id = context.User.GetProperty("id").GetString();
var email = context.User.GetProperty("email").GetString();
var name = context.User.GetProperty("name").GetString();
// TODO: SignIn user
return Task.CompletedTask;
};
});
services.AddScoped<AuthenticationStateProvider, RevalidatingIdentityAuthenticationStateProvider<ApplicationUser>>();
services.AddAuthenticationCore(options =>
{
options.DefaultAuthenticateScheme = IdentityConstants.ApplicationScheme;
options.DefaultChallengeScheme = IdentityConstants.ApplicationScheme;
options.DefaultSignInScheme = IdentityConstants.ExternalScheme;
});
}
public static void Configure(IApplicationBuilder app, IWebHostEnvironment env, IConfiguration configuration)
{
//...
app.UseRouting();
app.UseAuthentication();
app.UseAuthorization();
//...
app.UseEndpoints(endpoints =>
{
endpoints.MapControllers();
endpoints.MapBlazorHub();
endpoints.MapFallbackToPage("/_Host");
});
}