Authentication Using Google In ASP.NET Core 2.0

Click on continue.

{  
  "Authentication:Google:ClientId": "Your Google ClientId here",  
  "Authentication:Google:ClientSecret": "Your Google ClientSecret here"  
}

Now open Startup.cs file and put the following code into ConfigureServices method.

services.AddAuthentication().AddGoogle(googleOptions =>  
{  
    googleOptions.ClientId = Configuration["Authentication:Google:ClientId"];  
    googleOptions.ClientSecret = Configuration["Authentication:Google:ClientSecret"];  
});

In this code section we are reading ClientId and ClientSecret for authentication purposes. So finally, Startup.cs will look like this

using System;  
using System.Collections.Generic;  
using System.Linq;  
using System.Threading.Tasks;  
using Microsoft.AspNetCore.Builder;  
using Microsoft.AspNetCore.Identity;  
using Microsoft.EntityFrameworkCore;  
using Microsoft.AspNetCore.Hosting;  
using Microsoft.Extensions.Configuration;  
using Microsoft.Extensions.DependencyInjection;  
using GoogleAuth.Data;  
using GoogleAuth.Models;  
using GoogleAuth.Services;  
  
namespace GoogleAuth  
{  
    public class Startup  
    {  
        public Startup(IConfiguration configuration)  
        {  
            Configuration = configuration;  
        }  
  
        public IConfiguration Configuration { get; }  
  
        // This method gets called by the runtime. Use this method to add services to the container.  
        public void ConfigureServices(IServiceCollection services)  
        {  
            services.AddDbContext<ApplicationDbContext>(options =>  
                options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));  
  
            services.AddIdentity<ApplicationUser, IdentityRole>()  
                .AddEntityFrameworkStores<ApplicationDbContext>()  
                .AddDefaultTokenProviders();  
  
            services.AddAuthentication().AddGoogle(googleOptions =>  
            {  
                googleOptions.ClientId = Configuration["Authentication:Google:ClientId"];  
                googleOptions.ClientSecret = Configuration["Authentication:Google:ClientSecret"];  
            });  
  
            // Add application services.  
            services.AddTransient<IEmailSender, EmailSender>();  
  
            services.AddMvc();  
        }  
  
        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.  
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)  
        {  
            if (env.IsDevelopment())  
            {  
                app.UseBrowserLink();  
                app.UseDeveloperExceptionPage();  
                app.UseDatabaseErrorPage();  
            }  
            else  
            {  
                app.UseExceptionHandler("/Home/Error");  
            }  
  
            app.UseStaticFiles();  
  
            app.UseAuthentication();  
  
            app.UseMvc(routes =>  
            {  
                routes.MapRoute(  
                    name: "default",  
                    template: "{controller=Home}/{action=Index}/{id?}");  
            });  
        }  
    }  
}

And with this, our application is ready.

Execution Demo

Launch the application and click Login on the top right corner of the home page

You will be redirected to http://localhost:51792/Account/Login page, where you can see the option to login using Google on the right side of page.

Clicking on Google button will take you to the Google login page where you will be asked to fill in your Google credentials and authorize the Google app to use your Google account. After successful authentication from Google you will be redirected to a registration page inside our application where you need to fill in an email id to tag with your account. The Gmail id that you have used to login will already be populated in the Email id field. If you want to use another mail id you can change it here.

Click register, you will be redirected to home page again but this time you can also see your registered email is on the top right corner.

Conclusion

We have successfully created and configured Google+ app and implemented Google authentication in our ASP.NET Core application.

You can Get the source code from Github

Please note that secrets.json file contains dummy values. Hence replace the values with the keys of your Google app before executing it.

You can check my other articles on ASP .NET Core here

See Also