Log4Net.How can I change the file location programmatically c#?

Question

Hi, I am totally new to Log4net. I have managed to get something going by adding a config file and simple logging I have hardcoded the value to be "c:\temp\log.txt" but this is not good enough

The logs must go to the special folders

path=Enviroment.GetFolderPath(Enviroment.SpecialFolder.CommonApplicationData;

and this path changes depending whether you are in windows Server 2008 or winxp or vista etc...

How can I just change the location of the file in log4net programmatically?

This is what I have done

<configSections>
<section name=“log4net“                type=“log4net.Config.Log4NetConfigurationSectionHandler,Log4net“/>
  </configSections>
  <log4net>         
       <root>
             <level value=“DEBUG“ />
              <appender-ref ref=“LogFileAppender“ />
        </root>
        <appender name=“LogFileAppender“ type=“log4net.Appender.RollingFileAppender“ >
              <param name=“File“ value=“C:\temp\log.txt“ />
              <param name=“AppendToFile“ value=“true“ />
              <rollingStyle value=“Size“ />
              <maxSizeRollBackups value=“10“ />
              <maximumFileSize value=“10MB“ />
              <staticLogFileName value=“true“ />
              <layout type=“log4net.Layout.PatternLayout“>
          <param name=“ConversionPattern“ value=“%-5p%d{yyyy-MM-dd hh:mm:ss} – %m%n“ />
              </layout>
        </appender>
 </log4net>

--

class Program
{
  protected static readonly ILog log = LogManager.GetLogger(typeof(Program));
   static void Main(string[] args)
   {
       log4net.Config.XmlConfigurator.Configure();
       log.Warn(“Log something”);

       path=Enviroment.GetFolderPath(Enviroment.SpecialFolder.CommonApplicationData;


      //HOW CAN I CHANGE WHERE i LOG STUFF
   }
 }

Just need to figure out how I can change to log stuff to where i want to

Any suggestions? Thanks a lot

Answer 1

You need to dig through your logger's IAppenders and set the FileAppender.File to your required output path.

Here's a really good example.

Answer 2

log4net can handle this for you. Any appender property of type string can be formatted, in this case, using the log4net.Util.PatternString option handler. PatternString even supports the SpecialFolder enum which enables the following elegant config:

<appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender" >
    <file type="log4net.Util.PatternString" 
        value="%envFolderPath{CommonApplicationData}\\test.txt" />
    ...
</appender>

Here's a unit test that proofs the pudding:

[Test]
public void Load()
{
    XmlConfigurator.Configure();
    var fileAppender = LogManager.GetRepository()
        .GetAppenders().First(appender => appender is RollingFileAppender);

    var expectedFile = 
        Path.Combine(
            Environment.GetFolderPath(
                Environment.SpecialFolder.CommonApplicationData),
                "test.txt");

    Assert.That(fileAppender, 
        Is.Not.Null & Has.Property("File").EqualTo(expectedFile));
}

The following test verifies that log4net actually writes to disk (which basically makes this an "integration" test, not a unit test, but we'll leave it at that for now):

[Test]
public void Log4net_WritesToDisk()
{
    var expectedFile = 
        Path.Combine(
            Environment.GetFolderPath(
                Environment.SpecialFolder.CommonApplicationData),
                "test.txt");

    if (File.Exists(expectedFile))
        File.Delete(expectedFile);

    XmlConfigurator.Configure();

    var log = LogManager.GetLogger(typeof (ConfigTest));
    log.Info("Message from test");

    LogManager.Shutdown();

    Assert.That(File.ReadAllText(expectedFile), 
        Text.Contains("Message from test"));
}

NB: I strongly suggest using the compact property syntax demonstrated in the above sample. Removing all those "<property name=" makes your config that much more readable.

Answer 3

As an alternative to doing this programatically, you can use environment variables and customizable patterns in the configuration file. See this response to a similar question.

Look at "PatternString for pattern based configuration" in the Log4Net V1.2.10 release notes.

Also if you are thinking of writing to a directory such as Enviroment.SpecialFolder.CommonApplicationData you need to consider:

• Will all instances of your application for all users have write access to the log file? E.g. I don't believe non-administrators will be able to write to Enviroment.SpecialFolder.CommonApplicationData.

• Contention if multiple instances of your application (for the same or different users) are attempting to the same file. You can use the "minimal locking model" (see http://logging.apache.org/log4net/release/config-examples.html to allow multiple processes to write to the same log file, but there probably will be a performance impact. Or you could give each process a different log file, e.g. by including the process id in the filename using a customizable pattern.

Answer 4

Guys, Thanks for your replies very helpful.

Peter I am going to try whether that works as it's simple and could do the job.

Joe, Thanks for your answer,this is def something i want to dig deeper but time is not on my side if what Peter suggested works than I will be fine for now.

Need to deliver today.

thanks alot

Answer 5

Hi Peter this is my Log4net file do you see something wrong for some reasons it still does not seem to write to a file

<?xml version="1.0" encoding="utf-8" ?>
  <configuration>
    <configSections>
        <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,Log4net"/>
 </configSections>
 <log4net>
<root>
  <level value="DEBUG" />
  <appender-ref ref="LogFileAppender" />
 </root>
<appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender" >
  <file type="log4net.Util.PatternString"   value="%envFolderPath{CommonApplicationData}\\test.txt" />
  <param name="AppendToFile" value="true" />
  <rollingStyle value="Size" />
  <maxSizeRollBackups value="10" />
  <maximumFileSize value="10MB" />
  <staticLogFileName value="true" />
  <layout type="log4net.Layout.PatternLayout">
    <param name="ConversionPattern" value="%-5p%d{yyyy-MM-dd hh:mm:ss} – %m%n" />
  </layout>
</appender>
 </log4net>
 </configuration>

public class Bar { private static readonly ILog Log = LogManager.GetLogger(typeof(Bar));

        public void DoIt()
        {
            const string filePath = @"c:\MyConfigFiles\Log4net.config";
            XmlConfigurator.Configure(new FileInfo(filePath));

            Log.Info("Test");
        }
}