How to make log4net.Filter.StringMatchFilter work with acceptOnMatch set to false

Question

I've just started using log4net and have some issues with filtering using strings.

I'm trying to remove EPiServer specific logging in my log4net log file as I am not interested in it.

I have the following log4net configuration for an appender:

        <filter type="log4net.Filter.LevelRangeFilter">
           <levelMin value="DEBUG" />
        </filter>

        <filter type="log4net.Filter.StringMatchFilter">
            <stringToMatch value="EPiServer" />
            <acceptOnMatch value="false" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />

I only have one root logger. This config does not stop the EPiServer logging.

What am I doing wrong?

Answer 1

You should remove the line

<filter type="log4net.Filter.DenyAllFilter" />

From the docs:

You can add this filter to the end of a filter chain to switch from the default "accept all unless instructed otherwise" filtering behavior to a "deny all unless instructed otherwise" behavior.

Which effectively reverses the logic to deny all messages unless explicitly whitelisted inside a <filter> using <acceptOnMatch value="true" />

Answer 2

Try changing your StringMatchFilter to a LoggerMatchFilter

<filter type="log4net.Filter.LoggerMatchFilter">
  <loggerToMatch value="EPiServer" />
  <acceptOnMatch value="false" />  
</filter>

A StringMatchFilter filters on the content of the log message, where a LoggerMatch filters on the Logger's class Name or partial Namespace