nlog Extending NLog Create custom Layout Renderer

Example

[LayoutRenderer("hello-world")]
public class HelloWorldLayoutRenderer : LayoutRenderer
{

    /// <summary>
    /// I'm option and not required or default
    /// </summary>
    public string Config1 { get; set; }

    /// <summary>
    /// I'm required option. And error will be thrown if not set.
    /// </summary>
    [RequiredParameter]
    public string Config2 { get; set; }

    /// <summary>
    /// I'm the default parameter.
    /// The first parameter value (without name) will be set to this one
    /// You can set me as required also. 
    /// </summary>
    [DefaultParameter]
    public bool Caps {get;set;}

    protected override void Append(StringBuilder builder, LogEventInfo logEvent)
    {
        //TODO use options 
        builder.Append("hello world!");
    }
}

Register - as soon as possible - e.g. in main(), application_start().

//register under "hello-world"
ConfigurationItemFactory.Default.LayoutRenderers
                        .RegisterDefinition("hello-world", typeof(MyNamespace.HelloWorldLayoutRenderer ));

Usage

${hello-world} - raises exception: required parameter Config2 isn't set
${hello-world:Config2=abc} - OK, Config2 property set
${hello-world:true:config2=abc} - default parameter (Caps) set to true
${hello-world:true:config2=abc:config1=yes} - all the three properties set.