Logging Made Easy: Configuring and Using NLog with .NET Core

 To configure and use NLog with .NET Core, you need to follow these steps:

Step 1: Add NLog Dependencies In your .NET Core project, open the csproj file and add the following dependencies to the <ItemGroup> section:

<ItemGroup>
  <PackageReference Include="NLog.Web.AspNetCore" Version="4.14.0" />
  <PackageReference Include="NLog.Extensions.Logging" Version="1.7.0" />
</ItemGroup>

Save the file, and Visual Studio will automatically restore the packages.

Step 2: Configure NLog Create a new file called nlog.config in the root of your project. This file will contain the NLog configuration. Here's a basic example:

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      autoReload="true"
      internalLogLevel="Error"
      internalLogFile="c:\temp\nlog-internal.log">

  <targets>
    <target name="logfile" xsi:type="File" fileName="c:\temp\log.txt" />
    <!-- Additional targets can be added here -->
  </targets>

  <rules>
    <logger name="*" minlevel="Trace" writeTo="logfile" />
    <!-- Additional rules can be added here -->
  </rules>

</nlog>

In this example, we define a target named "logfile" that writes logs to a file called "log.txt" in the specified path. You can configure additional targets and rules according to your needs.

Step 3: Update appsettings.json Open the appsettings.json file in your project and add the following section:

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "NLog": {
    "LogLevel": {
      "Default": "Info",
      "Microsoft": "Warn",
      "System": "Info"
    }
  }
}

This configuration sets the log levels for the default .NET Core logging and NLog.

Step 4: Configure NLog in Startup.cs In your Startup.cs file, add the following code to the ConfigureServices method:

using Microsoft.Extensions.Logging;

public void ConfigureServices(IServiceCollection services)
{
    // Add NLog
    services.AddLogging(loggingBuilder =>
    {
        loggingBuilder.ClearProviders();
        loggingBuilder.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
    });
}

This code configures the logging system to use NLog and sets the minimum log level to Trace.

Step 5: Update Program.cs In your Program.cs file, update the CreateHostBuilder method to configure NLog as the logging provider:

using Microsoft.Extensions.Hosting;
using NLog.Web;

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureLogging(logging =>
        {
            logging.ClearProviders();
            logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
        })
        .UseNLog()
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

This code configures the host to use NLog for logging.

Step 6: Use NLog in Your Code You can now use NLog for logging in your application. Inject the ILogger<T> interface into your classes or controllers and use it for logging. For example:

using Microsoft.Extensions.Logging;

private readonly ILogger<HomeController> _logger;

public HomeController(ILogger<HomeController> logger)
{
    _logger = logger;
}

public IActionResult Index()
{
    _logger.LogInformation("Index page visited");
    return View();
}

In this example, we inject the ILogger<HomeController> into the HomeController class and use it to log an information message.

That's it! You have now configured and can use NLog for logging in your .NET Core application. Logs will be written to the specified targets based on the rules defined in the nlog.config file.