log4net: How to set logger file name dynamically?

Question

This is a really common question, but I have not been able to get an answer to work. Here is my configuration file:

<?xml version="1.0" encoding="utf-8"?>
<log4net>
  <appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
    <file value="CraneUserInterface.log" />
    <appendToFile value="true" />
    <maxSizeRollBackups value="90" />
    <rollingStyle value="Size" />

    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date - %message%newline" />
    </layout>
  </appender>

  <root>
    <level value="DEBUG" />
    <appender-ref ref="RollingFile" />
  </root>

But I need to determine the actual logging file name at run time. I found a nice example here, but when I try to loop through the collection returned by the call to GetIterators(), I find that that collection is empty.

I need to change the name "CraneUserInterface.log" to "CraneUserInterface_1.log", or 2, or 3, depending on something the program reads at run time. How can I do that?

Here's my first pass at using the code presented in that sample:

static bool ChangeLogFileName(string AppenderName, string NewFilename)
{           
   // log4net.Repository.ILoggerRepository RootRep;
   // RootRep = log4net.LogManager.GetRepository();
   log4net.Repository.ILoggerRepository RootRep = m_logger.Logger.Repository;
   foreach (log4net.Appender.IAppender iApp in RootRep.GetAppenders())
   {
   string appenderName = iApp.Name;
   if (iApp.Name.CompareTo(AppenderName) == 0
       && iApp is log4net.Appender.FileAppender)
   {
       log4net.Appender.FileAppender fApp = (log4net.Appender.FileAppender)iApp;
       fApp.File = NewFilename;
       fApp.ActivateOptions();
       return true; // Appender found and name changed to NewFilename
   }
}
return false; // appender not found
}

Thanks very much!

Answer 1

What about to use "%property" to define a dynamic 'tag' to the file name (at runtime) ?

<file type="log4net.Util.PatternString" value="~/App_Data/%property{LogName}" />

Explained here: Best way to dynamically set an appender file path

Answer 2

you can use this function : in this function first get file location that you set in webconfig and after that you can add any path that you want ! like Date ! our Customer ! or .....

WebConfig:

<appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
    <file value="C:\\t4\\"/>
    <appendToFile value="true"/>
    <rollingStyle value="Composite"/>
    <datePattern value="_yyyy-MM-dd.lo'g'"/>
    <maxSizeRollBackups value="10"/>
    <maximumFileSize value="1MB"/>
    <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date User:%identity IP:%X{addr} Browser: %X{browser} Url: %X{url} [%thread] %-5level %c:%m%n"/>
    </layout>
</appender>

Function:

public static void ChangeFileLocation(string _CustomerName,string _Project)
{
    XmlConfigurator.Configure();
    log4net.Repository.Hierarchy.Hierarchy h =(log4net.Repository.Hierarchy.Hierarchy)LogManager.GetRepository();

    foreach (IAppender a in h.Root.Appenders)
    {
        if (a is FileAppender)
        {
            FileAppender fa = (FileAppender)a;
            string sNowDate=  DateTime.Now.ToLongDateString();
            // Programmatically set this to the desired location here
            string FileLocationinWebConfig = fa.File;
            string logFileLocation = FileLocationinWebConfig + _Project + "\\" + _CustomerName + "\\" + sNowDate + ".log";

            fa.File = logFileLocation;
            fa.ActivateOptions();
            break;
        }
    }
}

and result like this : C:\t4\TestProject\Customer1\Saturday, August 31, 2013.log