Can I use two different layouts in one target in NLog? - nlog

Question

I have two layouts in nlog.config. once is Default layout and other one is ErrorLayout in which have additional properties.
the problem is i want to add target and i want to use both layout for LogLevel.Error i have to use ErrorLayout and for the other levels i have to use DefaultLayout. i don't want to create two target because two targets creating two different file and store logs into it.
but i want to both layout into one target.
can I able to do that? How ?
can anyone help me to do this ?

Answer 1

Another option is you use two targets, targeting the same file. If you don't enable keepfileopen, then this is also a good solution.
For example:
<nlog>
<targets>
<target type="file" name="erp" layout="${message}" fileName="log-${shortdate}.log" />
<target type="file" name="erp-error" layout="${message} ${exception:format=tostring}" fileName="log-${shortdate}.log" />
</targets>
<rules>
<logger name="*" minLevel="Error" writeTo="erp-error" final="true" /> <!-- after match events won't be processed futher due to the final attribute -->
<logger name="*" minLevel="Debug" writeTo="erp" />
</rules>
</nlog>

Answer 2

Right now your DefaultLayout and ErrorLayout are quite simple, so you can just do this:
<nlog>
<variable name="DefaultLayout" value="${message}" />
<variable name="ErrorLayout" value="${message} ${exception:format=tostring}" />
<variable name="DynamicLayout= value="${when:when=level<=LogLevel.Info:inner=${DefaultLayout}:else=${ErrorLayout}}" />
<targets>
<target type="file" name="erp" layout="${DynamicLayout}" fileName="log-${shortdate}.log" />
</targets>
<rules>
<logger name="*" minLevel="Debug" writeTo="erp" />
</rules>
</nlog>
See also https://github.com/nlog/NLog/wiki/When-Layout-Renderer
Notice NLog might perform poorly if you include heavy layoutrenders in the ErrorLayout. Ex. like ${callsite}