Question

We had our own custom logger in a C# program and now are trying to port to log4net.

In our app, there is further structure to what would normally go into %message. It may contain requestid, associated users, and other structure where requestid and user have internal significance to the program.

The hope is to ultimately be able to search on the fields inside %message, say requestid so we can collect all log entries with the same requestid for example.

Does log4net assist in anyway in creating own custom fields? The reason we ask is that currently the entire %message is logged as one string by default.

Any other suggestions on how to provide further formatting for %message? Otherwise we would have to pre-format %message inside our own code as, say, a CSV format

Answer 1

You can use event context to add additional structured data to a log entry:

http://www.beefycode.com/post/Log4Net-Tutorial-pt-6-Log-Event-Context.aspx

Depending on what kind of information you want to log you may need to create a wrapper that accepts additional parameters or else you have to write verbose code like this:

log4net.ThreadContext.Properties["myInformation"] = yourAdditionalInformation;
log.Info("info message");

Other information can be calculated and thus can be set once (for instance on application start up). Have a look at the calculated context properties in the above tutorial.