log4net/c# - Different layout based on the level

Question

Hi,

Is there any way to have different layout based on level of the log message when using log4net? Say, if it is a fatal error, I want to see all kind of information possible - class name, method name, line number etc. But for normal, debug and warning, I want to see only the message (I hope, this can increase the performance).

I am using log4net in C# WinForms. My requirement is to log all the previous 512 messages in to a file when a fatal error occures, and I want to see class name, method name, line number etc only for Fatal errors, for all other levels, just a message.

Answer 1

You could just use a different Appender for each "Level" and have them identical but for the pattern layout.

Answer 2

Yes, I can use different appenders, but I am using a BufferingForwardingAppender, so that I can buffer and log messages only when a Fatal error occurs. Do you know, how I can configure different appenders for each levels, and still works with BufferingForwardingAppender?

I hope I can configure 4 file appender for each level to log in to same file, and set filter to log only the desired level. But I am not sure whether this approach can save the messages in the same order as they come. Do you have any idea?

Answer 3

This post has a good explanation of a log4net config file:

log4net Configuration

Pay attention to the layout elements in the appenders. They define the pattern for how the error and any information you choose are output.

Answer 4

I think you're looking for LevelRangeFilter and a two-appender combination. One appender/filter combo for FATAL level (fatal being the min and max) and one appender/filter combo for everthing else (with ERROR or INFO being the max depending on if you wanted to include errors for debugging purposes)

Example here: http://stackoverflow.com/questions/619532/what-do-you-have-in-your-log4net-config-hacks-optimizations-observations