c#NLog如何只获取一个以longdate为文件名的日志文件

Question

Hello I am using for my console application NLog for logging. With that being said I would like to log everything that happens in the console using NLog to set that up I am using the NLOG.config:

  <target name="FullCSVFile" xsi:type="File"  fileName="logs\internal_${date:format=yyyyMMdd_HHmmss}.log" keepFileOpen="true">
  <layout xsi:type="CsvLayout">
    <column name="Console" layout="${message}" />
    <column name="Error" layout="${exception:format=ToString}" />
  </layout>
</target>

<logger minlevel="Debug" name="*" writeTo="FullCSVFile" />

But this way the tool makes a new file every second passed in the console, but I want to make one file when the tool starts with that timestamp and write everything in this one. How would I do that?

Answer 1

The trick is to use the ambient property cached=true like this:

<target name="FullCSVFile" xsi:type="File"  fileName="logs\internal_${date:format=yyyyMMdd_HHmmss:cached=true}.log" keepFileOpen="true">
  <layout xsi:type="CsvLayout">
    <column name="Console" layout="${message}" />
    <column name="Error" layout="${exception:format=ToString}" />
  </layout>
</target>

It will make layout render once, and then just return the same cached value.

See also: https://github.com/nlog/NLog/wiki/Cached-Layout-Renderer

Answer 2

Something like this could work, but I have not tested it:

  <variable name="started" value="${date:format=yyyyMMdd_HHmmss}"/>
  <target name="FullCSVFile" xsi:type="File" fileName="logs\internal_${started}.log" keepFileOpen="true">
    <layout xsi:type="CsvLayout">
      <column name="Console" layout="${message}" />
      <column name="Error" layout="${exception:format=ToString}" />
    </layout>
  </target>

The idea is similar to the example from the documentation: https://github.com/nlog/nlog/wiki/Configuration-file#variables