Authentication Using LinkedIn In ASP.NET Core 2.0

Open our web application once again and Right-click the project in Solution Explorer and select “Manage User Secrets” from the context menu.

A secrets.json file will open. Put the following code in it.

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

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

services.AddAuthentication().AddLinkedIn(options =>
{
    options.ClientId = Configuration["Authentication:LinkedIn:ClientId"];
    options.ClientSecret = Configuration["Authentication:LinkedIn:ClientSecret"];

    options.Events= new OAuthEvents()
    {
        OnRemoteFailure = loginFailureHandler =>
        {
            var authProperties = options.StateDataFormat.Unprotect(loginFailureHandler.Request.Query["state"]);
            loginFailureHandler.Response.Redirect("/Account/login");
            loginFailureHandler.HandleResponse();
            return Task.FromResult(0);
        }
    };

});

In this code section, we are reading Client ID and Client Secret values from secrets.json file for the authentication purpose. We are also handling the event of “OnRemoteFailure” in this code section. Hence, if the user deny the access to his LinkedIn account, then he will be redirected back to Login page.

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 LinkdinAuth.Data;
using LinkdinAuth.Models;
using LinkdinAuth.Services;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Authentication.OAuth;
  
namespace LinkdinAuth
{
    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().AddLinkedIn(options =>
            {
                options.ClientId = Configuration["Authentication:LinkedIn:ClientId"];
                options.ClientSecret = Configuration["Authentication:LinkedIn:ClientSecret"];
  
                options.Events= new OAuthEvents()
                {
                    OnRemoteFailure = loginFailureHandler =>
                    {
                        var authProperties = options.StateDataFormat.Unprotect(loginFailureHandler.Request.Query["state"]);
                        loginFailureHandler.Response.Redirect("/Account/login");
                        loginFailureHandler.HandleResponse();
                        return Task.FromResult(0);
                    }
                };
  
            }); 
  
            // 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 in the top right corner of the homepage.

You will be redirected to http://localhost:52676/Account/Login page, where you can see the option to login using LinkedIn on the right side of page.

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

Put in your LinkedIn credentials and click on Allow access button. The application will take few moments to authenticate your LinkedIn account and upon successful authentication with LinkedIn, 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.

Give an email id and click register, you will be redirected to the homepage again but this time you can also see your registered email id at the top right corner. Hence, we have successfully logged in to our ASP .NET Core application using LinkedIn.

Conclusion

We have successfully created a LinkedIn 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 LinkedIn app before executing it.

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

See Also