Using Nlog | Logging | Csharp Tutorial

Introduction

NLog is a flexible and free logging platform for various .NET platforms, including .NET standard. It is one of the most popular logging frameworks for .NET applications, providing powerful and easy-to-use features for logging.

Installation

To use NLog in your C# application, you need to install the NLog package via NuGet. You can do this using the NuGet Package Manager in Visual Studio or by using the Package Manager Console.

Install NLog using the Package Manager Console:

Install-Package NLog

Basic Configuration

After installing NLog, you need to configure it. This configuration can be done in a configuration file (NLog.config) or programmatically. In this tutorial, we will use the NLog.config file for configuration.

Create a file named NLog.config in the root of your project and add the following basic configuration:

<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <targets>
    <target name="logfile" xsi:type="File" fileName="file.txt" />
  </targets>
  <rules>
    <logger name="*" minlevel="Info" writeTo="logfile" />
  </rules>
</nlog>

This configuration specifies that all log messages with a level of Info or higher should be written to a file named file.txt.

Using NLog in Code

Now that NLog is configured, you can use it in your C# code. First, you need to import the NLog namespace:

using NLog;

Next, create a logger instance and log some messages:

using System;
using NLog;

class Program
{
    private static readonly Logger Logger = LogManager.GetCurrentClassLogger();

    static void Main(string[] args)
    {
        Logger.Info("This is an info message");
        Logger.Warn("This is a warning message");
        Logger.Error("This is an error message");

        Console.WriteLine("Logging complete. Check the log file for output.");
    }
}

In this example, we create a static logger instance using LogManager.GetCurrentClassLogger() and use it to log messages of different levels (Info, Warn, Error).

Advanced Configuration

NLog supports a variety of advanced configuration options. Here are a few examples:

Multiple Targets

You can log messages to multiple targets (e.g., file, console, database). Here is an example configuration:

<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <targets>
    <target name="logfile" xsi:type="File" fileName="file.txt" />
    <target name="logconsole" xsi:type="Console" />
  </targets>
  <rules>
    <logger name="*" minlevel="Info" writeTo="logfile,logconsole" />
  </rules>
</nlog>

In this example, log messages are written to both a file and the console.

Logging Layouts

You can customize the layout of log messages. Here is an example configuration:

<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <targets>
    <target name="logfile" xsi:type="File" fileName="file.txt" layout="${longdate} ${uppercase:${level}} ${message}" />
  </targets>
  <rules>
    <logger name="*" minlevel="Info" writeTo="logfile" />
  </rules>
</nlog>

In this example, the log messages include the date, the log level in uppercase, and the message.

Conclusion

In this tutorial, we covered the basics of using NLog in a C# application. We discussed how to install NLog, configure it using a configuration file, and log messages in code. We also looked at some advanced configuration options. NLog is a powerful and flexible logging framework, and this tutorial should provide you with a solid foundation to start using it in your projects.

Using NLog in C#