How do configure "when" conditional NLog rules? - nlog

Question

I am trying to log conditional NLogs. I always pass a string (Rule1 or Rule2 in this example) that specifies what rule as the first part of a message.
My problem is that with the current rules below, both rules are being marked "true" and log files. I can't see how that is possible. I'm using the strings of "Rule1" and "Rule2" for this example, but the actual strings passed are completely different (not the same word with a different number).
Example messages that are getting passed to be logged are...
Ex1: ${message} = "Rule1,Information about the rule,foo
Ex2: ${message} = "Rule2,Information about the other rule,bar
Here are my example targets
<!-- language: config -->
<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd"
autoReload="true"
throwExceptions="false"
internalLogLevel="Off" internalLogFile="c:\temp\nlog-internal.log"
keepVariablesOnReload="true">
<variable name="dir_Logging" value="C:/<myPath>"/>
<variable name="dir_Archive_Rule1" value="${dir_Logging}/Log Archives/Rule1/${shortdate}"/>
<variable name="dir_Archive_Rule2" value="${dir_Logging}/Log Archives/Rule2/${shortdate}"/>
<variable name="varRule1" value="Rule1"/>
<variable name="varRule2" value="Rule2"/>
<targets>
<target xsi:type="File" name="rule1Logs"
archiveOldFileOnStartup="true"
archiveNumbering="Date"
archiveDateFormat="yyyy-MM-dd_HH-mm-ss"
fileName="${dir_Logging}/Logs - Rule1.csv"
archiveFileName="${dir_Archive_Rule1}/Logs - Rule1.{#}.csv">
<layout xsi:type="SimpleLayout"
text=""${date:format= yyyy/MM/dd}","${date:format= HH\:mm\:ss.fff}",${message}"/>
</target>
<target xsi:type="File" name="rule2Logs"
archiveOldFileOnStartup="true"
archiveNumbering="Date"
archiveDateFormat="yyyy-MM-dd_HH-mm-ss"
fileName="${dir_Logging}/Logs - Rule2.csv"
archiveFileName="${dir_Archive_Rule2}/Logs - Rule2.{#}.csv">
<layout xsi:type="SimpleLayout"
text=""${date:format= yyyy/MM/dd}","${date:format= HH\:mm\:ss.fff}",${message}"/>
</target>
</targets>
<rules>
<logger name="*" level="Info" writeTo="rule1Logs">
<filters>
<when condition="starts-with('${message}','${varRule1}')" action="Log"/>
</filters>
</logger>
<logger name="*" level="Info" writeTo="rule2logs">
<filters>
<when condition="starts-with('${message}','${varRule2}')" action="Log"/>
</filters>
</logger>
</rules>

Answer 1

The default of the filter is "neutral", so if it won't match your filter, it get logged.
This is a known limitation and will be addressed in NLog 4.6 (See code change in NLog 4.6)
For now you need to:
inverse the condition and action=ignore
OR, add a 2nd filter that ignores all