In this post, I will show you how to Built-In Logging In .NET Core. For an application, logging is very important to keep track of that application and keep it error-free.

In .NET Core, we don't need any third party logging; instead, we can use built-in logging whenever we want. This is very efficient in terms of code and performance. Now, develope a new .NET Core application and name it.

Step 1: Go to Package mManager View-->Other Windows--> Package manager Console  -->

Install-Package Microsoft.Extensions.Logging

Add Logging
Once  the extension's installed, we can add logging by adding ILogger<T> (custom logging) or ILoggerFactory. If we want to use ILoggerFactory, then we must create it using CreateLogger, to use logging add logging services under ConfigureServices. Moreover, we can use built-in logging with the other loggings (like Nlog) with very minimal code.
services.AddLogging(); 

Startup.cs
public class Startup 
    { 
        public Startup(IHostingEnvironment env) 
        { 
            var builder = new ConfigurationBuilder() 
                .SetBasePath(env.ContentRootPath) 
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true) 
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true) 
                .AddEnvironmentVariables(); 
            Configuration = builder.Build(); 
        } 
 
        public IConfigurationRoot Configuration { get; } 
 
        // This method gets called by the runtime. Use this method to add services to the container. 
        public void ConfigureServices(IServiceCollection services) 
        { 
            // Add framework services. 
            services.AddMvc(); 
            services.AddLogging(); 
        } 
 
        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline. 
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) 
        { 
            loggerFactory.AddConsole(Configuration.GetSection("Logging")); 
            loggerFactory.AddDebug(); 
 
            if (env.IsDevelopment()) 
            { 
                app.UseDeveloperExceptionPage(); 
                app.UseBrowserLink(); 
            } 
            else 
            { 
                app.UseExceptionHandler("/Home/Error"); 
            } 
 
            app.UseStaticFiles(); 
 
            app.UseMvc(routes => 
            { 
                routes.MapRoute( 
                    name: "default", 
                    template: "{controller=Home}/{action=Index}/{id?}"); 
            }); 
        } 
    } 

ILoggerFactory: We can use  ILoggerFactory. For this, we must use CreateLogger.

_logger = Mylogger.CreateLogger(typeof(HomeController)); 

HomeController.cs
public class HomeController : Controller 
    { 
        private ILogger _logger; 
 
        public HomeController(ILoggerFactory Mylogger) 
        { 
            _logger = Mylogger.CreateLogger(typeof(HomeController)); 
        } 
 
        public IActionResult Index() 
        { 
            return View(); 
        } 
 
        public IActionResult About() 
        { 
            try 
            { 
                ViewData["Message"] = "Your application description page."; 
                _logger.LogInformation("About Page has been Accessed"); 
                return View(); 
            } 
            catch (System.Exception ex) 
            { 
                _logger.LogError("About: " + ex.Message); 
                throw; 
            } 
        } 
 
        public IActionResult Contact() 
        { 
            try 
            { 
                ViewData["Message"] = "Your contact page."; 
                _logger.LogInformation("Contact Page has been Accessed"); 
                return View(); 
            } 
            catch (System.Exception ex) 
            { 
                _logger.LogError("Contact: " + ex.Message); 
                throw; 
            } 
        } 
 
        public IActionResult Error() 
        { 
            return View(); 
        } 
    } 

Run and Test

LogLevel: We can add logging level by adding the level we want in appsettings.json.Trace

• Debug
• Information
• Warning
• Error
• Application failure or crashes