NLog DB Configuration - nlog

Question

From the docs https://github.com/NLog/NLog/wiki/Database-target
It seems settings are shown as attributes on the target element such as:
<target xsi:type="Database"
name="String"
dbUserName="Layout"
dbProvider="String"
and in the example below as separate child nodes:
<target name="database" xsi:type="Database">
<connectionStringName>NLogDb</connectionStringName>
Neither work for me, I just get Invalid configuration exceptions with this message:
NotSupportedException: Parameter connectionStringName not supported on DatabaseTarget
The Config File:
<?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="info"
throwExceptions="true"
internalLogFile="c:\temp\internal-nlog.txt">
<!-- enable asp.net core layout renderers -->
<extensions>
<add assembly="NLog.Web.AspNetCore"/>
</extensions>
<!-- the targets to write to -->
<targets>
<!-- write logs to file -->
<target xsi:type="File" name="allfile" fileName="c:\temp\nlog-all-${shortdate}.log"
layout="${longdate}|${event-properties:item=EventId_Id}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}" />
<!-- another file log, only own logs. Uses some ASP.NET core renderers -->
<target xsi:type="File" name="ownFile-web" fileName="c:\temp\nlog-own-${shortdate}.log"
layout="${longdate}|${event-properties:item=EventId_Id}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}|url: ${aspnet-request-url}|action: ${aspnet-mvc-action}" />
<target xsi:type="Database"
name="database"
keepConnection="true"
useTransactions="true"
dbProvider="System.Data.SqlClient"
connectionStringName="DefaultConnection"
commandText="INSERT INTO Logs (EventDateTime, EventLevel, UserName, MachineName, EventMessage, ErrorSource, ErrorClass, ErrorMethod, ErrorMessage, InnerErrorMessage) VALUES (#EventDateTime, #EventLevel, #UserName, #MachineName, #EventMessage, #ErrorSource, #ErrorClass, #ErrorMethod, #ErrorMessage, #InnerErrorMessage)">
<parameter name="#EventDateTime" layout="${date:s}" />
<parameter name="#EventLevel" layout="${level}" />
<parameter name="#UserName" layout="${aspnet-user-identity}" />
<parameter name="#MachineName" layout="${machinename}" />
<parameter name="#EventMessage" layout="${message}" />
<parameter name="#ErrorSource" layout="${event-context:item=error-source}" />
<parameter name="#ErrorClass" layout="${event-context:item=error-class}" />
<parameter name="#ErrorMethod" layout="${event-context:item=error-method}" />
<parameter name="#ErrorMessage" layout="${event-context:item=error-message}" />
<parameter name="#InnerErrorMessage" layout="${event-context:item=inner-error-message}" />
</target>
</targets>
<!-- rules to map from logger name to target -->
<rules>
<!--All logs, including from Microsoft-->
<logger name="*" minlevel="Trace" writeTo="allfile,database" />
<!--Skip non-critical Microsoft logs and so log only own logs-->
<logger name="Microsoft.*" maxLevel="Info" final="true
" />
<!-- BlackHole without writeTo -->
<logger name="*" minlevel="Trace" writeTo="ownFile-web" />
</rules>
</nlog>
How it is being called in program.cs
var logger = NLog.Web.NLogBuilder.ConfigureNLog( "nlog.config" ).GetCurrentClassLogger();
(copied from their docs)
Must be missing something obvious, but since there is conflicting info in the docs, and copying other people's configs posted on here, not sure where to go with it

Answer 1

Looks like you are running on NetCore. NLog is not able to read connectionStringName from AppSettings.json as you have found out yourself (Requires extra dependencies to access IConfiguration).
One possible solution is using this extension:
https://www.nuget.org/packages/NLog.Appsettings.Standard/
And use connectionString (Instead of connectionStringName) in NLog.config:
<extensions>
<add assembly="NLog.Web.AspNetCore"/>
<add assembly="NLog.Appsettings.Standard"/>
</extensions>
<target xsi:type="Database" connectionString="${appsettings:name=ConnectionStrings.DefaultConnection}">
Alternative solution is to assign a GDC variable before logging:
NLog.GlobalDiagnosticsContext.Set("DefaultConnection", Configuration.GetConnectionString("DefaultConnection"));
And then use GDC in NLog.config:
<target xsi:type="Database" connectionString="${gdc:item=DefaultConnection}">
See also https://github.com/NLog/NLog/wiki/Gdc-layout-renderer
Update NLog.Extension.Logging ver. 1.4.0
With NLog.Extension.Logging ver. 1.4.0 then you can now use ${configsetting}
See also: https://github.com/NLog/NLog/wiki/ConfigSetting-Layout-Renderer