NLog console highlight properties

Question

I've watched the following video explaining about Serilog. I would like to use structured logging in my application as well (at least parts of it), but I prefer to use NLog (1) because it's already part of our stack and we're used to it and prefer to have the same logger on across our projects, and (2) I have read the comparison here and seems like NLog is more performant.

So I read that NLog also support structured logging and I have implemented it in a test application without a problem. It works very well.

What I saw in the video and liked about Serilog, is when writing to console it highlights the parameters passed to the logging function like this:

I would like to have the same on the console application I'm currently building. I have tried both Console target and ColoredConsole but non has that effect. Is it possible in NLog?

This is my targets configurations:

<target name="file"
            xsi:type="File"
            archiveEvery="Day"
            archiveFileName="Logs\log.{#}.txt"
            fileName="Logs\log.txt"
            archiveNumbering="DateAndSequence"
            archiveDateFormat="yyyy-MM-dd"
            archiveAboveSize="104857600"
            maxArchiveFiles="30"
            layout="${longdate} | ${uppercase:${level}} | ${logger} | ${threadid} | ${message} ${exception}"
            />

    <target xsi:type="ColoredConsole"
          name="ColorConsole"
          layout="${uppercase:${level}}: ${message} ${exception:innerFormat=Message,StackTrace}"
          header="Memoriez API"
          useDefaultRowHighlightingRules="false"
          >
      <highlight-word foregroundColor="Green" ignoreCase="true" text="info" wholeWords="true" />
      <highlight-word foregroundColor="Red" ignoreCase="true" text="warn" wholeWords="true" />
      <highlight-word backgroundColor="Red" foregroundColor="White" ignoreCase="true" text="error" wholeWords="true" />
      <highlight-row backgroundColor="DarkRed" foregroundColor="Yellow" condition="level == LogLevel.Fatal" />
    </target>

Answer 1

I do not think you can colorized the parameters in ColoredConsoleTarget. It might be possible to use WordHighlighting, but you would quickly run into issues where matching a number would highlight all numbers and not just the parameter.

My guess is that you would need to write a custom ColoredConsoleTarget in order to highlight parameters. I just looked at the src\NLog\Targets\ColoredConsoleTarget.cs file and it only offers RowHighlightingRules and WordHighlightingRules. It looks like when the color codes are applied the LogEventInfo has been rendered into a plain string.

I think you would need to write a custom RenderLogEvent function that would render the color escape sequences for parameters. It would be a bit tricky because the GenerateColorEscapeSequences for WordHighlighting would escape any color sequences generated before it is called).

Here are my thoughts:

1. Create a new class ColoredParamConsoleTarget with code copied from ColoredConsoleTarget. It doesn't look like there are virtual methods to just override the existing class.
2. Create a ColoredRenderLogEvent method and parse for parameters and add color sequences before and after parameters.
3. Replace calls to RenderLogEvent with ColoredRenderLogEvent