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:

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Answer 1

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

Answer 2

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