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.
  1. services.AddLogging();
Startup.cs
  1. public class Startup
  2. {
  3. public Startup(IHostingEnvironment env)
  4. {
  5. var builder = new ConfigurationBuilder()
  6. .SetBasePath(env.ContentRootPath)
  7. .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
  8. .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
  9. .AddEnvironmentVariables();
  10. Configuration = builder.Build();
  11. }
  13. public IConfigurationRoot Configuration { get; }
  15. // This method gets called by the runtime. Use this method to add services to the container.
  16. public void ConfigureServices(IServiceCollection services)
  17. {
  18. // Add framework services.
  19. services.AddMvc();
  20. services.AddLogging();
  21. }
  23. // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
  24. public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
  25. {
  26. loggerFactory.AddConsole(Configuration.GetSection("Logging"));
  27. loggerFactory.AddDebug();
  29. if (env.IsDevelopment())
  30. {
  31. app.UseDeveloperExceptionPage();
  32. app.UseBrowserLink();
  33. }
  34. else
  35. {
  36. app.UseExceptionHandler("/Home/Error");
  37. }
  39. app.UseStaticFiles();
  41. app.UseMvc(routes =>
  42. {
  43. routes.MapRoute(
  44. name: "default",
  45. template: "{controller=Home}/{action=Index}/{id?}");
  46. });
  47. }
  48. }
ILoggerFactory: We can use ILoggerFactory. For this, we must use CreateLogger.
  1. _logger = Mylogger.CreateLogger(typeof(HomeController));
HomeController.cs
  1. public class HomeController : Controller
  2. {
  3. private ILogger _logger;
  5. public HomeController(ILoggerFactory Mylogger)
  6. {
  7. _logger = Mylogger.CreateLogger(typeof(HomeController));
  8. }
  10. public IActionResult Index()
  11. {
  12. return View();
  13. }
  15. public IActionResult About()
  16. {
  17. try
  18. {
  19. ViewData["Message"] = "Your application description page.";
  20. _logger.LogInformation("About Page has been Accessed");
  21. return View();
  22. }
  23. catch (System.Exception ex)
  24. {
  25. _logger.LogError("About: " + ex.Message);
  26. throw;
  27. }
  28. }
  30. public IActionResult Contact()
  31. {
  32. try
  33. {
  34. ViewData["Message"] = "Your contact page.";
  35. _logger.LogInformation("Contact Page has been Accessed");
  36. return View();
  37. }
  38. catch (System.Exception ex)
  39. {
  40. _logger.LogError("Contact: " + ex.Message);
  41. throw;
  42. }
  43. }
  45. public IActionResult Error()
  46. {
  47. return View();
  48. }
  49. }
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.