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!

Kiushu

Answer 1

I usually add something this... (it's all the functionality I need)

MethodBase.GetCurrentMethod().Name

you could always create a wrapper for Log4Net that takes any params you need (like MethodBase)?

Uncertainty

Thanks - I would like to avoid passing down type and methodName. – Kiushu

Answer 2

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.

Cheerless

Hi, This fails in release mode. It simply saves "?" in class name and method name. Did you face such issue? If so, any idea? – Collegian

Never had this problem. I could imagine that the compiler is inlining your method? – Cheerless

Yeah, The Log4Net documentation too suggests the same i.e. It is using System.Diagnostics.StackTrace which works differently in release mode :-( – Collegian

Answer 3

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

Wham

I like this solution but it is not working with static methods. Any suggestions? – Larger