When using wrapper, how to preserve class and method name for Log4Net to log?

Question

I need a Log4net wrapper - to be exposed to a number of different components in a large app. I obviously want to retain the class and method name when logging but I would keep away of passing down type etc to my wrapper.

I had a look at this question which is very similar to mine, but it didn't help.

I've seen it done in this other question with smt like the following:

MethodBase methodBase = new StackTrace().GetFrame(1).GetMethod();
this.log.Debug(methodBase.Name + " : " + message);

This is not ideal since it's not using the out-of-the-box Log4Net functionality.

I'd like to get an idea of how people are doing this before I go for the tangent and come up with something very complicated. Any pointers (links/resources/samples) appreciated!

Answer 1

Log4net allows you to access method name for instance like this %method. This is not the fastest operation but if you need to debug something you may very well use it. I believe your question is about the fact that log4net will not output the correct method name if you use a wrapper.

To solve that problem you have to look at how log4net wrote the ILog implementation. This is basically a wrapper around the internal log4net Logger and therefore the very same problem applies to the ILog implementation, too. I did basically the following:

// define a field such as this
private static readonly Type ThisDeclaringType = typeof(MyLogWrapper);

// in constructor. Note: I use the internal Logger!
this.Logger = LogManager.GetLogger(name).Logger;

// I created a WriteLog method that calls the internal logger like this
// you will need to translate to the internal log levels
// message and ex are the items I want to log (ex can be null)
this.Logger.Log(MyLogWrapper.ThisDeclaringType, log4netLevel, message, ex);

Obviously there are some things to do yet, but the important points are mentioned.

Answer 2

Create your wrapper class like this...

public static class LogFourNet
    {
        // Define a static logger variable so that it references the
        private static readonly ILog Log = LogManager.GetLogger(typeof(LogFourNet));

        static LogFourNet()
        {
            XmlConfigurator.Configure(
                   new FileInfo(AppDomain.CurrentDomain.BaseDirectory + "log4net.config"));
            Log.Info("Log4net is configured.");
        }

        public static void Info(object currentObj, string msg, [CallerLineNumber] int lineNumber = 0,
            [CallerFilePath] string caller = "", [CallerMemberName] string memberName = "")
        {
            Log.Info("[" + currentObj.GetType().Namespace + "." +
                     Path.GetFileNameWithoutExtension(caller) + "." + memberName + ":" + lineNumber + "] - " + msg);
        }

        public static void Debug(object currentObj, string msg, [CallerLineNumber] int lineNumber = 0,
            [CallerFilePath] string caller = "", [CallerMemberName] string memberName = "")
        {
            Log.Debug("[" + currentObj.GetType().Namespace + "." +
                      Path.GetFileNameWithoutExtension(caller) + "." + memberName + ":" + lineNumber + "] - " + msg);
        }

        public static void Error(object currentObj, string msg, [CallerLineNumber] int lineNumber = 0,
            [CallerFilePath] string caller = "", [CallerMemberName] string memberName = "")
        {
            Log.Error("[" + currentObj.GetType().Namespace + "." +
                      Path.GetFileNameWithoutExtension(caller) + "." + memberName + ":" + lineNumber + "] - " + msg);
        }
    }

Configure your log4net.config file in the following manner...

<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
  </configSections>
  <log4net>
    <appender name="FileAppender" type="log4net.Appender.FileAppender">
      <file value="logfile.log" />
      <appendToFile value="true" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%d [%t] %-5p - %m%n" />
      </layout>
    </appender>
    <root>
      <!--LogLevel: OFF, FATAL, ERROR, WARN, INFO, DEBUG, ALL -->
      <level value="ALL" />
      <appender-ref ref="FileAppender" />
    </root>
  </log4net>
</configuration>

Now just use above these methods like this...

// need to pass this(current obj) as we want to log full class name
LogFourNet.Debug(this, "started something from wrapper");

output:
-------
2017-02-04 15:38:37,549 [1] DEBUG [WebAPI_DI.Startup.Configuration:25] - started something from wrapper