Вот проверенное средство визуализации макета, которое регистрирует уровень журнала как целое число. Способ получения уровней журнала, возможно, немного за борт, но я проходил фазу linq; -)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NLog;
using NLog.LayoutRenderers;
namespace MyNLogExtensions.NLog
{
[LayoutRenderer("LogLevelOrdinal")]
class LogLevelOrdinalLayoutRenderer : LayoutRenderer
{
IDictionary<LogLevel, int> ordinals;
public override void Initialize()
{
base.Initialize();
ordinals = GetLogLevels()
.OrderBy(level => level)
.Select((level, index) => new { Level = level, Ordinal = index })
.ToDictionary( x => x.Level, x => x.Ordinal);
}
protected override void Append(StringBuilder builder, LogEventInfo logEvent)
{
int level = 0;
if (!ordinals.TryGetValue(logEvent.Level, out level)) level = 99;
builder.Append(level);
}
protected override int GetEstimatedBufferSize(LogEventInfo logEvent)
{
return 1;
}
//
// LogLevel is a static class with a static member for each of the different log levels.
// The LogLevel ordinal is not exposed publically (i.e. an ordinal indicating the relative
// "importance" of a LogLevel value).
// The implementation of LogLevel.GetHashCode actually does return the ordinal, but it doesn't
// seem right to rely on that implementation detail.
// In the end, this LayoutRenderer is really just to allow for producing a numeric value to represent
// a particular log level value's "position" relative to the other lob levels. As such,
// We can just get all of the known log level values, order them (they are sortable), and assign our
// own ordinal based on the position of the log level value in the resulting sorted list.
//
// This helper function exposes the known log level values as IEnumerable<LogLevel> so that we can
// easily use LINQ to build a dictionary to map LogLevel to ordinal.
//
internal IEnumerable<LogLevel> GetLogLevels()
{
yield return LogLevel.Trace;
yield return LogLevel.Debug;
yield return LogLevel.Info;
yield return LogLevel.Warn;
yield return LogLevel.Error;
yield return LogLevel.Fatal;
}
}
}