Logging with NLog

Logging is an absolute must-have feature, which is too convenient and easy to not do it. When I start a new project it is something I will pretty much do on the first days because it brings immediate advantages:

• for debugging
• for commenting / understanding code
• you have an actual document to discuss over with other departments

NLog

NLog is a flexible and free logging platform for various .NET platforms, including .NET standard. NLog makes it easy to write to several targets. (database, file, console) and change the logging configuration on-the-fly.

https://nlog-project.org/

And also very important NLog is licensed under the BSD 3-Clause, which means you can use it for free for private and commercial use on the condition that you write its copyright notice in your documentation. See https://github.com/NLog/NLog/blob/master/LICENSE.txt

In order to log with NLog you will need the following:

1. NLog binaries
2. Configuration file
3. Call to the dll in source Code

See https://github.com/nlog/nlog/wiki/Tutorial

NLog Binaries

You can either add NLog over Nugget in your Visual Studio project or add a specific version of the nlog.dll in your binaries.

See https://www.nuget.org/packages/NLog

Configuration file

I like to have an external dedicated file for it, I usually call it nlog.config and store it with the binaries. Remember to configure File Properties: Copy If newer

<?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">

  <targets>
    <target name="logfile"
            xsi:type="File"
            fileName="${specialfolder:folder=CommonApplicationData}/Company/Product/log/${shortdate}.log"
            layout="${longdate} ${uppercase:${level}} ${message}" />
    <target name="logconsole"
            xsi:type="Console"
            layout="${longdate} ${uppercase:${level}} ${message}" />
    <target name="logfileNamespace"
            xsi:type="File"
            fileName="${specialfolder:folder=CommonApplicationData}/Company/Product/log/${shortdate}_Namespace.log"
            layout="${longdate} ${uppercase:${level}} ${message}" />
  </targets>

  <rules>
    <logger name="*" minlevel="Info" writeTo="logconsole" />
    <logger name="*" minlevel="Info" writeTo="logfile" />
    <logger name="Company.Department.Product.Namespace" minlevel="Trace" writeTo="logfileNamespace" />
  </rules>
</nlog>

https://github.com/nlog/nlog/wiki/Configuration-file

Logging

In order to use NLog you will need to define a Log object first, this should be done in every class where you want to log. and is done with

private static readonly NLog.Logger Log = NLog.LogManager.GetCurrentClassLogger();

Then you will be able to call the following functions:

• Trace() very high volume of detailed Information, used for developping
• Debug() more than the default level of Information, used for debugging
• Info() default level of information, typically used in the field, used for retracing program activity
• Warn() warnings, these are expected problems that are handled by the program
• Error() errors, these are somehow expected but the described function/feature cannot continue/fulfill its normal operation
• Fatal() fatal error, unexpected serious error, it makes no sense to continue program execution

namespace ConsoleApp1
{
    public class Program
    {
        private static readonly NLog.Logger Log = NLog.LogManager.GetCurrentClassLogger();

        public static void Main(string[] args)
        {
            Log.Info("### Starting Program ###");
            Log.Info($"Version: {System.Reflection.Assembly.GetExecutingAssembly().GetName().Version}");
            Log.Info($"Date: {System.DateTime.Now}");
            Log.Info($"OS Description: {System.Runtime.InteropServices.RuntimeInformation.OSDescription}");
            Log.Info($"OS Architecture: {System.Runtime.InteropServices.RuntimeInformation.OSArchitecture}");
        }
    }
}

2020-04-07 22:25:10.8128 INFO ### Starting Program ###
2020-04-07 22:25:10.8592 INFO Version: 1.0.0.0
2020-04-07 22:25:10.8592 INFO Date: 07.04.2020 22:25:10
2020-04-07 22:25:10.8592 INFO OS Description: Microsoft Windows 10.0.18363
2020-04-07 22:25:10.8592 INFO OS Architecture: X64