Authentication Using Facebook In ASP.NET Core 2.0

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 FacebookAuth.Data;  
using FacebookAuth.Models;  
using FacebookAuth.Services;  
  
namespace FacebookAuth  
{  
    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().AddFacebook(facebookOptions =>  
            {  
                facebookOptions.AppId = Configuration["Authentication:Facebook:AppId"];  
                facebookOptions.AppSecret = Configuration["Authentication:Facebook:AppSecret"];  
            });  
  
            // 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 home page.

You will be redirected to http://localhost:54575/Account/Login page, where you can see the option to login using Facebook on the right side of the page.

Clicking on the  Facebook button will take you to the Facebook authorization page where you will be asked to fill in your Facebook credentials and authorize the Facebook app to use your Facebook account.

Put in your Facebook credentials and click on Login button. You will now see a confirmation page as shown below. Click on Continue as <name> button.

The application will take a few moments to authenticate your Facebook account and upon successful authentication with Facebook, 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 email id that you have used to login to Facebook will be populated in Email id field. If you want to use another mail id you can change it.

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

Conclusion

We have successfully created a Facebook app and used it to authenticate 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