Log4Net, how to add a custom field to my logging

Question

I use the log4net.Appender.AdoNetAppender appender.
My log4net table are the following fields [Date],[Thread],[Level],[Logger],[Message],[Exception]

Answer 1

Here is a working version with some personalized preferences. I added a custom column for storing a generated exception code.

1) Add your custom column(exceptionCode here) to Log4net config:

2) Log4NetExtentedLoggingCustomParameters.cs

namespace Common.Utils.LogHelper
{
    public class Log4NetExtentedLoggingCustomParameters
    {
        public string ExceptionCode { get; set; }

        public string Message { get; set; }

        public override string ToString()
        {
            return Message;
        }
    }
}

3) Log4NetExtentedLoggingPatternConverter.cs

namespace Common.Utils.LogHelper
{
    public class Log4NetExtentedLoggingPatternConverter : PatternConverter
    {
        protected override void Convert(TextWriter writer, object state)
        {
            if (state == null)
            {
                writer.Write(SystemInfo.NullText);
                return;
            }

            var loggingEvent = state as LoggingEvent;
            var messageObj = loggingEvent.MessageObject as Log4NetExtentedLoggingCustomParameters;

            if (messageObj == null)
            {
                writer.Write(SystemInfo.NullText);
            }
            else
            {
                switch (this.Option.ToLower()) //this.Option = "Code"
                {
                    case "code": //config conversionPattern parameter -> %exceptionCode{Code}
                        writer.Write(messageObj.ExceptionCode);
                        break;  
                    default:
                        writer.Write(SystemInfo.NullText);
                        break;
                }
            }
        }
    }
}

4) Log4NetExtentedLoggingPatternLayout.cs

namespace Common.Utils.LogHelper
{
    public class Log4NetExtentedLoggingPatternLayout : PatternLayout
    {
        public Log4NetExtentedLoggingPatternLayout()
        {
            var customConverter = new log4net.Util.ConverterInfo()
            {
                Name = "exceptionCode",
                Type = typeof(Log4NetExtentedLoggingPatternConverter)
            };

            AddConverter(customConverter);
        }
    }
}

5) Logger.cs // Enjoy your logger with new column! :)

namespace Common.Utils.LogHelper
{
    public class Logger
    {
        static ILog Logger = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);

        public static string LogError(string message, Exception exception = null)
        {
            var logWithErrCode = GetLogWithErrorCode(message);
            Logger.Error(logWithErrCode, exception);
            return logWithErrCode.ExceptionCode;
        }

        private static Log4NetExtentedLoggingCustomParameters GetLogWithErrorCode(string message)
        {
            var logWithErrCode = new Log4NetExtentedLoggingCustomParameters();
            logWithErrCode.ExceptionCode = GenerateErrorCode(); //this method is absent for simplicity. Use your own implementation
            logWithErrCode.Message = message;
            return logWithErrCode;
        }
    }
}

references:

http://blog.stvjam.es/2014/01/logging-custom-objects-and-fields-with