Built-In Logging In .NET Core

Introduction

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.

 

Let’s start.

Create 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                   

Summary

We can use built-in logging frameworks and separate our application from logger implementation so that we can use the same framework later for other logging providers.