NLog config Example

Save this file as "nlog.config" in the root of your application (Add to project with Copy if newer)

Simple config example:

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      autoReload="true"
      internalLogLevel="Warn"
      internalLogFile="${basedir}/nlog-internal.txt">

    <variable name="defaultLayout" value="${longdate}|${level}|${message:withException=true}" />

    <targets>
        <target name="logfile" xsi:type="File" fileName="file.txt" layout="${defaultLayout}" />
        <target name="console" xsi:type="ColoredConsole" layout="${defaultLayout}" />
    </targets>

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

Advanced config example:

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      autoReload="true"
      internalLogLevel="Warn"
      internalLogFile="${basedir}/logs/nlog-internal.txt">

  <variable name="gmailUsername" value="${trim-whitespace:${file-contents:${basedir}/gmailusername.txt}}" />
  <variable name="gmailPassword" value="${trim-whitespace:${file-contents:${basedir}/gmailpassword.txt}}" />

  <extensions>
    <!-- load NLog.Web to enable ASP.NET-specific functionality -->
    <add assembly="NLog.Web" />
  </extensions>

  <!-- define various log targets -->
  <targets>
    <!-- write logs to file -->
    <target xsi:type="File" name="file" fileName="${basedir}/logs/${shortdate}.log"
            layout="${longdate} ${aspnet-request:servervariable=URL} ${uppercase:${level}} ${message}" />

    <!-- write log message to database -->
    <target xsi:type="Database" name="db">
      <!-- SQL command to be executed for each entry -->
      <commandText>INSERT INTO [LogEntries](TimeStamp, Message, Level, Logger) VALUES(getutcdate(), @msg, @level, @logger)</commandText>

      <!-- parameters for the command -->
      <parameter name="@msg" layout="${message}" />
      <parameter name="@level" layout="${level}" />
      <parameter name="@logger" layout="${logger}" />

      <!-- connection string -->
      <dbProvider>System.Data.SqlClient</dbProvider>
      <connectionString>server=.\SQLEXPRESS;database=MyLogs;integrated security=sspi</connectionString>

      <!-- commands to install database -->
      <install-command>
        <text>CREATE DATABASE MyLogs</text>
        <connectionString>server=.\SQLEXPRESS;database=master;integrated security=sspi</connectionString>
        <ignoreFailures>true</ignoreFailures>
      </install-command>

      <install-command>
        <text>
          CREATE TABLE LogEntries(
          id int primary key not null identity(1,1),
          TimeStamp datetime2,
          Message nvarchar(max),
          level nvarchar(10),
          logger nvarchar(128))
        </text>
      </install-command>

      <!-- commands to uninstall database -->
      <uninstall-command>
        <text>DROP DATABASE MyLogs</text>
        <connectionString>server=.\SQLEXPRESS;database=master;integrated security=sspi</connectionString>
        <ignoreFailures>true</ignoreFailures>
      </uninstall-command>
    </target>

    <!-- log message to event log -->
    <target xsi:type="EventLog" name="eventLog" source="NLog Demo"
            layout="${message}${newline}Call site: ${callsite:className=true:methodName=true}${newline}Logger: ${logger}">
    </target>

    <!-- increase the performance counter -->
    <target xsi:type="PerfCounter" name="pc1" categoryName="My Log" counterName="My Counter">
    </target>

    <!-- send mail through GMail server -->
    <target xsi:type="Mail"
            name="mail"
            smtpServer="smtp.gmail.com"
            smtpPort="587"
            enableSsl="true"
            smtpAuthentication="Basic"
            smtpUserName="${gmailUsername}"
            smtpPassword="${gmailPassword}"
            from="${gmailUsername}"
            to="${gmailUsername}"
            subject="NLogDemo logs"
            addNewLines="true"
            />

    <!-- send mail asynchronously, so that it does not block the calling thread -->
    <wrapper-target xsi:type="AsyncWrapper" name="asyncMail">
      <target-ref name="mail"/>
    </wrapper-target>

    <wrapper-target xsi:type="AspNetBufferingWrapper" name="allOutputs">
      <wrapper-target xsi:type="PostFilteringWrapper">
        <compound-target xsi:type="SplitGroup">
          <target-ref name="file" />
          <target-ref name="db" />
          <target-ref name="eventLog" />
          <target-ref name="pc1" />
          <target-ref name="asyncMail" />
        </compound-target>
        
        <!-- during normal execution only log Info messages -->
        <defaultFilter>level >= LogLevel.Info</defaultFilter>
        
        <!-- if there is at least one error, log everything from trace level -->
        <when exists="level >= LogLevel.Error" filter="level >= LogLevel.Trace" />
      </wrapper-target>
    </wrapper-target>
  </targets>

  <rules>
    <logger name="*" minlevel="Trace" writeTo="allOutputs" />
  </rules>
</nlog>