CODEWITHSUNDEEP
c#dependency-injectionnlog
Stephen Cossgrove
Stephen Cossgrove

Reputation: 303

Layout Renderer with Dependency Injection Not Working

I have followed the https://github.com/NLog/NLog/wiki/How-to-write-a-custom-layout-renderer article to create a layout renderer. The hello-world example works find, but when I go it inject something it is not writting anything.

  1. I've removed the constructor injection and the logging is working as expected.
  2. I've injected the same item into a constructor of a controller and that works.
// NOTE: ICorrelationContextAccessor is part of the CorrelationId nuget package
[LayoutRenderer("correlation-id")]
public class CorrelationIdLayoutRenderer : LayoutRenderer
{
    private readonly ICorrelationContextAccessor _correlationContext;

    public CorrelationIdLayoutRenderer(ICorrelationContextAccessor correlationContext)
    {
        _correlationContext = correlationContext;
    }

    protected override void Append(StringBuilder builder, LogEventInfo logEvent)
    {
        var correlation = _correlationContext.CorrelationContext.CorrelationId;

        builder.Append(correlation);
    }
}

nlog.config

<extensions>
    <add assembly="NLog.Web.AspNetCore"/>
    <add assembly="[[ My assembly is here]]"/>
</extensions>
<targets>
 <target xsi:type="File" name="ownFile-web" fileName="[[PATH]]/nlog-own-${shortdate}.log"
                layout="${longdate}|${level:fixedLength=True:padding=5:padCharacter= :upperCase=True}|${correlation-id}|${message} ${exception:format=tostring}" />
</targets>

I expect that the correlation should be coming through.

Upvotes: 0

Views: 825

Answers (1)

Julian
Julian

Reputation: 36750

You need to override the CreateInstance in NLog, so it could create the CorrelationIdLayoutRenderer

ConfigurationItemFactory.Default.CreateInstance = (Type type) =>
{ 
    // your custom target.
    if(type == typeof(CorrelationIdLayoutRenderer))
      return new CorrelationIdLayoutRenderer(...); // TODO get ICorrelationContextAccessor 
    else
      return Activator.CreateInstance(type); //default
};

Update:

If you registering is too late, you could queue a reload of all assemblies by NLog as follows: 

ConfigurationItemFactory.Default = null; // (namespace NLog.Config).

It will be reloaded just before first usage of NLog

Upvotes: 1

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