I have messages in my logs like this

2025-03-07 14:47:38.7205 INFO System.Net.Http.HttpClient.signed.LogicalHandler Start processing HTTP request POST http://localhost:5000/api/KATA/scans?sensorInstanceId=instance1
2025-03-07 14:47:38.7266 TRACE System.Net.Http.HttpClient.signed.LogicalHandler Request Headers: Content-Type: multipart/form-data; boundary="48f29d53-2916-4b86-bc52-3283ad131dfc"

I want to receive only warnings and errors from System.Net.Http.HttpClient.*.

This is my nlog.config:

<?xml version="1.0" encoding="utf-8" ?>
    <nlog xmlns=".xsd"
          xmlns:xsi=";
          xsi:schemaLocation=".xsd NLog.xsd"
              autoReload="true">
    <targets>
        <target xsi:type="File" name="fileTarget" fileName="${basedir}/logs/${shortdate}.log" 
                    layout="${longdate} ${uppercase:${level}} ${logger} ${message}" />
        <target xsi:type="ColoredConsole" name="consoleTarget"  layout="${longdate} ${uppercase:${level}} ${logger} ${message}" />
    </targets>
    <rules>
        <logger name="*" minlevel="Trace" writeTo="consoleTarget" >
        <logger name="*" minlevel="Trace"x writeTo="fileTarget">    
            <filters defaultAction="Log">
                <when condition="contains('${logger}', 'System.Net.Http.HttpClient') and level < LogLevel.Info" action="Ignore" />
            </filters>
        </logger>
    </rules>
</nlog>

But my filter doesn't work. I tried filter without level and it works:

<when condition="contains('${logger}', 'System.Net.Http.HttpClient')" action="Ignore" />

How to write a filter with a level?

I have messages in my logs like this

2025-03-07 14:47:38.7205 INFO System.Net.Http.HttpClient.signed.LogicalHandler Start processing HTTP request POST http://localhost:5000/api/KATA/scans?sensorInstanceId=instance1
2025-03-07 14:47:38.7266 TRACE System.Net.Http.HttpClient.signed.LogicalHandler Request Headers: Content-Type: multipart/form-data; boundary="48f29d53-2916-4b86-bc52-3283ad131dfc"

I want to receive only warnings and errors from System.Net.Http.HttpClient.*.

This is my nlog.config:

<?xml version="1.0" encoding="utf-8" ?>
    <nlog xmlns="http://www.nlog-project./schemas/NLog.xsd"
          xmlns:xsi="http://www.w3./2001/XMLSchema-instance"
          xsi:schemaLocation="http://www.nlog-project./schemas/NLog.xsd NLog.xsd"
              autoReload="true">
    <targets>
        <target xsi:type="File" name="fileTarget" fileName="${basedir}/logs/${shortdate}.log" 
                    layout="${longdate} ${uppercase:${level}} ${logger} ${message}" />
        <target xsi:type="ColoredConsole" name="consoleTarget"  layout="${longdate} ${uppercase:${level}} ${logger} ${message}" />
    </targets>
    <rules>
        <logger name="*" minlevel="Trace" writeTo="consoleTarget" >
        <logger name="*" minlevel="Trace"x writeTo="fileTarget">    
            <filters defaultAction="Log">
                <when condition="contains('${logger}', 'System.Net.Http.HttpClient') and level < LogLevel.Info" action="Ignore" />
            </filters>
        </logger>
    </rules>
</nlog>

But my filter doesn't work. I tried filter without level and it works:

<when condition="contains('${logger}', 'System.Net.Http.HttpClient')" action="Ignore" />

How to write a filter with a level?

• nlog

Share Follow edited Mar 7 at 18:08 Rolf Kristensen 20.1k22 gold badges5858 silver badges8383 bronze badges asked Mar 7 at 12:03 SullenManSullenMan 5744 bronze badges

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1 Answer 1

Sorted by: Reset to default 1

Logging-Rules are much faster than filters, as the filter requires allocation of LogEventInfo to execute the filter.

I recommend that you use finalMinLevel to suppress noisy loggers, that has been introduced with NLog v5:

<?xml version="1.0" encoding="utf-8" ?>
    <nlog xmlns="http://www.nlog-project./schemas/NLog.xsd"
          xmlns:xsi="http://www.w3./2001/XMLSchema-instance"
          xsi:schemaLocation="http://www.nlog-project./schemas/NLog.xsd NLog.xsd"
          autoReload="true"
          throwConfigExceptions="true">
    <targets>
        <target xsi:type="File" name="fileTarget" fileName="${basedir}/logs/${shortdate}.log" 
                    layout="${longdate} ${uppercase:${level}} ${logger} ${message}" />
        <target xsi:type="ColoredConsole" name="consoleTarget"  layout="${longdate} ${uppercase:${level}} ${logger} ${message}" />
    </targets>
    <rules>
        <logger name="*" minlevel="Trace" writeTo="consoleTarget" />
        <logger name="System.Net.Http*" finalMinLevel="Warn" />
        <logger name="*" minlevel="Trace" writeTo="fileTarget" />
    </rules>
</nlog>

See also: https://github/NLog/NLog/wiki/Logging-Rules-FinalMinLevel