NLog - Only log while debugging

Question

Take this simple NLog example configuration:

<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

    <targets>
        <target name="logfile" xsi:type="File" fileName="file.txt" />
    </targets>

    <rules>
        <logger name="*" minlevel="Debug" writeTo="logfile" />
    </rules>
</nlog>

How can this be set up to only log while debugging, and not when run in production?

EDIT:

To make things a bit more challenging: My NLog configuration files are centralized, shared over all applications/services/sites. So I would like to avoid altering every single project and just modify the config files.

Answer 1

I see three solutions here.

1) Using config file and its transformations. For the moment the transformations are supported for web applications (Im talking about VS2012). For desktop app you need to install additional extension.

2) Use two targets, one for development (I assume debugging=development in your case) and the second for production. At runtime you need to leave actual one by removing the other.

UPDATE

3) If you don't want to alter the projects it is possible to apply custom conditions to the logger depending on custom Layout Renderer (see example of how to make a custom layout renderer). In your case the layout renderer should return current Build Configuration (Debug or Release) of executing assembly. As a result the condition will look like this:

<rules>
    <logger name="*" writeTo="logfile">
        <filters>
            <when condition="equals('${buildConfiguration}','Release')" action="Ignore" />
        </filters>
    </logger>
</rules>

where ${buildConfiguration} is your custom layout renderer.

PS And dont forget to put this

<extensions>
    <add assembly="NameOfMyAssemblyThatContainsMyLayoutRenderer" />
</extensions>

to the nlog.config so NLog knows about the layout renderer.