Is this the correct way to log to a specific target with NLog?

Question

I'd like to log some special events into a different table that will contain more data then the general application log.

If I add a second database target to the NLog.config how can I use it in my code?

Would this be the right thing to do:

NLog
    .LogManager
    .Configuration
    .AllTargets
    .Single(x => x.Name == "mySecondLogTable")
    .WriteAsyncLogEvent(...);

Then in the NLog.config I would just skip this target in the rules element, right?

Summary: I'd like to define multiple database targets like a general log and specialized log for cases where I need to log more details into a different table. I'd like to use the general log by default and the special log only in functions that need this special kind of logging because of their business logic.

I'd use only config settings and no source code. The config file is a mix of Targets & Rules. You can use it to control where the entries are written. — Fabrizio Accatino
Agreeing with @FabrizioAccatino. XML configurations may seem daunting at first, but I highly recommend it for NLog. It makes the process much more understandable, and you can easily make highly configurable targets/rules. — Flater
Yes, I also prefer XML configurations but I found only this so I thought I'd better ask if this is ok because I had the feeling I'm doing something terribly wrong. — t3chb0t

EngineerSpock EngineerSpock · Accepted Answer · 2015-03-10T09:08:03

You can always create another logger instance and use the NLog LoggingRules for redirection to the wanted target.

For example I want to make an extended logging into a separate file. Then I go and create:

<nlog>
  <rules>
    <!--- Notice that final=true stops the logevents from also reaching defaultTarget -->
    <logger name="ExtendedLogging" minlevel="Trace" writeTo="extendedTarget" final="true" />
    <!--- Wildcard rule will capture all logevents not matching the "final" rule above -->
    <logger name="*" minlevel="Trace" writeTo="defaultTarget" />
  </rules>
    
  <targets>
    <target name="extendedTarget" xsi:type="File" fileName="ExtendedLog_${shortdate}.log" />
    <target name="defaultTarget" xsi:type="File" fileName="AppLog_${shortdate}.log" />
  </targets>
</nlog>

And then I go to the code and create

private readonly Logger logger = LogManager.GetLogger("ExtendedLogging");

I don't think it's a good idea to search for something inside the config-file and perform logging through something like a backdoor. It's better to make all this things explicitly.

See also: https://github.com/nlog/nlog/wiki/Configuration-file#rules

Is this the correct way to log to a specific target with NLog?

2 Answers