Question

I try to find a way to set isdebugenabled false or true in configuration file,

so I can turn it on or off whenever I need. Thanks !

Answer 1

Using a really simple logging setup

<targets>
  <target xsi:type="File"
          name="debug"
          fileName="c:\temp\debug.txt"
          layout="${longdate} ${uppercase:${level}} ${message}" 
  />
</targets>

<rules>
  <logger name="*" minlevel="Trace" writeTo="debug" />
</rules>

And an equally simple code sample

class Program
{
    static void Main(string[] args)
    {
        var logger = new NLog.LogFactory().GetCurrentClassLogger();

        if (logger.IsDebugEnabled)
        {
            logger.Debug("this is a debug message");
        }

        logger.Debug("this is another debug message");
    }
}

When minLevel is set to Debug or Trace, both logger.Debug statements will write to the log. If you raise minLevel to a higher level (Info, Warn, Off) neither statement will be written to the log. logger.Debug checks IsDebugEnabled (which is inferred from the log level).

You can certainly get a performance increase (in cases where you are going to be logging calculated values and not just strings) by checking IsDebugEnabled, and changing minLevel for the logger is the way to toggle this.