Asp.Net Mvc Logging Using Nlog Complete Guide

Step 1: Create a New ASP.NET MVC Project

1. Open Visual Studio.
2. File -> New -> Project.
3. Select "ASP.NET Web Application (.NET Framework)" under the web category.
4. Give your project a name (e.g., MvcLoggingExample) and click "Create".
5. In the "New ASP.NET Web Application" window, choose "MVC" under the ASP.NET 4.x Templates and click "Create".

Step 2: Install NLog

You can use NuGet Package Manager to install NLog in your project.

1. Right-click on your project in the Solution Explorer.
2. Go to "Manage NuGet Packages".
3. Search for "NLog.Web.Mvc" and install it.

Step 3: Configure NLog

1. Open the newly created nlog.config file located in the root directory of your project.
2. Set up targets and rules for logging. Here’s a simple example configuration:

<?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"
      throwConfigExceptions="true">

  <!-- define various log targets -->
  <targets>
    <!-- write logs to file -->
    <target xsi:type="File" name="allfile" fileName="logs/mvcapp-all-${shortdate}.log"
            layout="${longdate}|${uppercase:${level}}|${aspnet-traceidentifier}|${message} ${exception:format=tostring}" />
    <target xsi:type="File" name="ownFile-web" fileName="logs/mvcapp-own-${shortdate}.log"
              layout="${longdate}|${uppercase:${level}}|${aspnet-traceidentifier}|${message} ${exception:format=tostring}" />

    <!-- optionally write logs to console while debugging 
    see https://github.com/nlog/nlog/wiki/Console-target-->
    <target xsi:type="Console" name="console" layout="${longdate}|${uppercase:${level}}|${message} ${exception:format=tostring}" />
  </targets>

  <!-- setup rules -->
  <rules>
    <!--All logs, including from Microsoft-->
    <logger name="*" minlevel="Trace" writeTo="allfile" />
    
    <!--Skip non-critical Microsoft logs and so log only own logs-->
    <logger name="Microsoft.*" maxlevel="Info" final="true" /> <!-- blackhole without log -->
    <logger name="*" minlevel="Debug" writeTo="ownFile-web" />
    <logger name="*" minlevel="Debug" writeTo="console" />
  </rules>
</nlog>

Step 4: Ensure Proper File Folder Creation

Make sure the folder specified for logs (logs) exists and that your application has write permissions to this folder. You may need to create this manually or through code.

1. Manually create a folder named logs in your project root.
2. Alternatively, add the following lines in your Application_Start method to ensure that the logs folder exists:

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    BundleConfig.RegisterBundles(BundleTable.Bundles);

    string logDirectory = Server.MapPath("~/logs");
    if (!Directory.Exists(logDirectory))
    {
        Directory.CreateDirectory(logDirectory);
    }
}

Step 5: Modify Controllers to Use NLog

1. First, open HomeController.cs.
2. Add the NLog logger to the Controller class.

using System;
using System.IO;
using System.Web.Mvc;
using NLog;

namespace MvcLoggingExample.Controllers
{
    public class HomeController : Controller
    {
        private static readonly Logger Logger = LogManager.GetCurrentClassLogger();

        public ActionResult Index()
        {
            Logger.Info("Visited Home page.");
            return View();
        }

        public ActionResult About()
        {
            ViewBag.Message = "Your application description page.";

            Logger.Info("Visited About page.");
            Logger.Debug("Debugging information here.");

            return View();
        }

        public ActionResult Contact()
        {
            ViewBag.Message = "Your contact page.";

            Logger.Info("Visited Contact page.");

            try
            {
                // Simulate something that could throw an exception
                int result = 10 / 0;
            }
            catch (Exception ex)
            {
                Logger.Error(ex, "Error occurred in Home Contact action.");
            }

            return View();
        }
    }
}

Step 6: Test the Logging

1. Run your application.
2. Navigate to the Index, About, and Contact pages.
3. Check the files in the logs directory to confirm that log entries are being captured.

Sample Output:

• Index Log Entry:

2023-10-01 10:15:23.7890|INFO|RequestTraceIdentifier|Visited Home page.

• About Log Entry:

2023-10-01 10:15:35.1230|DEBUG|RequestTraceIdentifier|Debugging information here.
2023-10-01 10:15:35.1230|INFO|RequestTraceIdentifier|Visited About page.

• Contact Log Entry:

2023-10-01 10:16:00.5670|ERROR|RequestTraceIdentifier|Error occurred in Home Contact action.
System.DivideByZeroException: Attempted to divide by zero.

Step 7: Clean Up

Ensure that NLog is properly initialized and shut down when the application ends. Add the following lines at the end of Global.asax.cs.

protected void Application_End()
{
    LogManager.Shutdown();
}

Conclusion

You now have a basic logging system in place with NLog in your ASP.NET MVC application. You can further customize NLog according to your application's needs by modifying the nlog.config file and adding more loggers where required. Happy coding!

Additional Notes:

• NLog Configuration: Customize the nlog.config file as per your requirements. You can add multiple targets like database, mail, etc.
• Log Levels: Differentiate between the log levels (Trace, Debug, Info, Warn, Error, Fatal) based on your logging needs.
• Custom Layouts: Define custom log layouts for better readability and more information.