log4net AppenderSkeleton ignores PatternLayout

Question

I created my own Appender with log4net,

 public class TextBoxAppender : AppenderSkeleton
{
      ...(constructor and other stuff omitted)...

        protected override void Append(log4net.Core.LoggingEvent loggingEvent)
        {
              var msg = string.Concat(loggingEvent.RenderedMessage, "\r\n");

              _textBox.AppendText(s);

        }

}

My App.config has a PatternLayout which I would like to use,

 <appender name="TextBoxAppender" type="log4netAppender.TextBoxAppender">
      <root>
        <level value="DEBUG">
          <appender-ref ref="TextBoxAppender">
          </appender-ref>
        </level>
      </root>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date{dd MMM yyyy HH:mm:ss} %level - %message%newline%exception%newline" />
      </layout>
    </appender>

loggingEvent.RenderedMessage doesn't give me the string formatted with PatternLayout.

I saw AppendSkeleton has this signature

public virtual ILayout Layout { get; set; }

but I don't want to write my own Layout, i would like to use the "standard" one which other Appenders use...

Any idea anyone? Thanks a lot

TIP: maybe this way we can access the renderer of other existing loggers?

var hierarchy = (Hierarchy)LogManager.GetRepository();
hierarchy.RendererMap .....

SOLUTION

in Append(), right before RenderLoggingEvent, set the Layout, which otherwise is null.

this.Layout = new log4net.Layout.PatternLayout("%date{dd MMM yyyy HH:mm:ss} %level - %message");
string msg = base.RenderLoggingEvent(loggingEvent);

samy samy · Accepted Answer · 2015-03-23T12:34:15

Call the base method RenderLoggingEvent to write your event according yo tour layout. For example here is the Append method in the TraceAppender

// log4net.Appender.TraceAppender
protected override void Append(LoggingEvent loggingEvent)
{
    Trace.Write(base.RenderLoggingEvent(loggingEvent), this.m_category.Format(loggingEvent));
    if (this.m_immediateFlush)
    {
        Trace.Flush();
    }
}

so in your case:

public class TextBoxAppender : AppenderSkeleton
{
    ...(constructor and other stuff omitted)...
    protected override void Append(log4net.Core.LoggingEvent loggingEvent)
    {
        // format your message in the layout, not here
        // var msg = string.Concat(loggingEvent.RenderedMessage, "\r\n");
        _textBox.AppendText(base.RenderLoggingEvent(loggingEvent));
    }
}

log4net AppenderSkeleton ignores PatternLayout

2 Answers