Change log4net logging level programmatically


We had one requirement in which we wanted to change the logging level of log4net programmatically based on the value passed.

Suppose this is how we have configured log4net in our application.

<?xml version="1.0"?>
 <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
 <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
 <file value="TestLog.txt"/>
 <appendToFile value="true"/>
 <rollingStyle value="Composite"/>
 <datePattern value="yyyyMMdd"/>
 <maxSizeRollBackups value="10"/>
 <maximumFileSize value="10MB"/>
 <layout type="log4net.Layout.PatternLayout">
 <conversionPattern value="[%d{yyyy-MM-dd HH:mm:ss}] [%p] [%c:%L] - %m%n"/>
 <level value="DEBUG"/>
 <appender-ref ref="RollingLogFileAppender"/>
<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/></startup></configuration>

The sample code for changing the log level

namespace SampleLogApp
 using System.Reflection;

using log4net;
 using log4net.Core;
 using log4net.Repository;
 using log4net.Repository.Hierarchy;
 using log4net.Config;

public partial class Form1 : Form

 private static readonly ILog logger = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
 private List<Person> lstPerson;

 public Form1()
 // configure the log4net logging

private void btnStartLogging_Click(object sender, EventArgs e)
 foreach(Person person in lstPerson)
 // set the logging type depending on person
 logger.Debug("Debug: " + person.FullName);
 logger.Info("Info: " + person.FullName);
 logger.Warn("Warn: " + person.FullName);
 logger.Error("Error: " + person.FullName);

private void Form1_Load(object sender, EventArgs e)
 lstPerson = new List<Person>();
 lstPerson.Add(new Person() { FullName = "Abhinav Ranjan", LogType = "Debug" });
 lstPerson.Add(new Person() { FullName = "Nirav Pancholi", LogType = "Info" });
 lstPerson.Add(new Person() { FullName = "Shobhit Bhatnagar", LogType = "Error" });

/// <summary>
 /// Sets the logging level.
 /// </summary>
 /// <param name="logType">Type of the log.</param>
 private static void SetLoggingLevel(string logType)
 Logger currentLogger = (Logger)logger.Logger;
 currentLogger.Level = currentLogger.Hierarchy.LevelMap[logType];

The output in TestLog.txt

[2012-04-16 00:17:27] [DEBUG] [SampleLogApp.Form1:39] – Debug: Abhinav Ranjan
[2012-04-16 00:17:27] [INFO] [SampleLogApp.Form1:40] – Info: Abhinav Ranjan
[2012-04-16 00:17:27] [WARN] [SampleLogApp.Form1:41] – Warn: Abhinav Ranjan
[2012-04-16 00:17:27] [ERROR] [SampleLogApp.Form1:42] – Error: Abhinav Ranjan
[2012-04-16 00:17:27] [INFO] [SampleLogApp.Form1:40] – Info: Nirav Pancholi
[2012-04-16 00:17:27] [WARN] [SampleLogApp.Form1:41] – Warn: Nirav Pancholi
[2012-04-16 00:17:27] [ERROR] [SampleLogApp.Form1:42] – Error: Nirav Pancholi
[2012-04-16 00:17:27] [ERROR] [SampleLogApp.Form1:42] – Error: Shobhit Bhatnagar

The helpful post

Hope it helps.


Author: Nishant Rana

I love working in and sharing everything about Microsoft.NET technology !

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