How do I use a date pattern in a header/footer?

Question

Here's my appender configuration from my app.config. This just prints out the literal string instead of translating it to the date (i.e., it literally prints "[START: %date{MM/dd/yy HH:mm} ]").

<appender name="RollingLogFileAppender"
          type="log4net.Appender.RollingFileAppender">
  <file value="C:\somelog" />
  <appendToFile value="true" />
  <rollingStyle value="Date" />
  <datePattern value="-yyyy-MM-dd'.txt'" />
  <layout type="log4net.Layout.PatternLayout">
    <header value="[START:  %date{MM/dd/yy HH:mm} ]&#13;&#10;" />
    <conversionPattern value="%date{yyyy-MM-dd HH:mm:ss} - %message" />
    <footer value="[END]&#13;&#10;&#13;&#10;" />
  </layout>
</appender>

How can I get this to print the date/time in the header?

Answer 1

Building on @Wizou's comment. See the DynamicPatternLayout Class documentation.

I'm actually using this difference in behaviour to have a start and end time

One important difference between PatternLayout and DynamicPatternLayout is the treatment of the Header and Footer parameters in the configuration. The Header and Footer parameters for DynamicPatternLayout must be syntactically in the form of a PatternString, but should not be marked as type log4net.Util.PatternString. Doing so causes the pattern to be statically converted at configuration time and causes DynamicPatternLayout to perform the same as PatternLayout.

Setting the type on Header to PatternString but leaving Footer as dynamic

<layout type="log4net.Layout.DynamicPatternLayout"> <param name="Header" value="%newline**** Trace Opened Local: %date{yyyy-MM-dd HH:mm:ss.fff} UTC: %utcdate{yyyy-MM-dd HH:mm:ss.fff} ****%newline" type="log4net.Util.PatternString" /> <param name="Footer" value="**** Trace Closed %date{yyyy-MM-dd HH:mm:ss.fff} ****%newline" /> </layout>

Answer 2

Answer from here.

<layout type="log4net.Layout.DynamicPatternLayout">
  ...
  <header value="[BEGIN LOGGING AT %date]%newline"/>
  <footer value="[END LOGGING AT %date]%newline"/>
  ...
</layout>

Works for me like a charm. No need to write a piece of code.

Also in projects we usually use:

<header type="log4net.Util.PatternString" value="Our Application Name version %property{Assembly.Version}, .NET version %property{Runtime.Version}, %date ***%newline"/>

Take a look at PatternString doc also.

Also I've noticed that log file won't appear until you write first log statement.