How can I use a RichTextBox as a NLog Target in a WPF application?

Question

I read the following posts but neither helped to just get the same efficient way of printing logs from NLog onto a RichTextBox control target as in Winforms.

How can I use NLog's RichTextBox Target in WPF application?

WPF: Binding RichTextBox to Logger Output

I also browsed the official forum but with no success (except suggestions to read the two above posts).

The idea would be to add the target as:

<target xsi:type="RichTextBox" name="console"
     layout="${longdate:useUTC=true}|${level:uppercase=true}|${logger}::${message}"
     autoScroll="true"
     maxLines="1000000"
     controlName="rtbConsole"
     formName="MyWPFWindowName"
     useDefaultRowColoringRules="true">
</target>

And within the WPF window with MyWPFWindowName as name, to add a RichTextBox control with rtbConsole. Even if I create the target programmatically after the winow has been loaded, it will not use the existing rtbConsole but create a new form.

So, your help is appreciated!

Answer 1

I created a custom NLog target and linked it to a text box.

public class NlogMemoryTarget : Target
{
    public Action<string> Log = delegate { };

    public NlogMemoryTarget (string name, LogLevel level)
    {
        LogManager.Configuration.AddTarget (name, this);

        LogManager.Configuration.LoggingRules.Add(new LoggingRule("*", level, this));//This will ensure that exsiting rules are not overwritten
        LogManager.Configuration.Reload(); //This is important statement to reload all applied settings

        //SimpleConfigurator.ConfigureForTargetLogging (this, level); //use this if you are intending to use only NlogMemoryTarget  rule
    }

    protected override void Write (AsyncLogEventInfo[] logEvents)
    {
        foreach (var logEvent in logEvents) {
            Write (logEvent);
        }
    }

    protected override void Write (AsyncLogEventInfo logEvent)
    {
        Write (logEvent.LogEvent);
    }

    protected override void Write (LogEventInfo logEvent)
    {
        Log (logEvent.FormattedMessage);
    }
}


public partial class MainWindow
{
    private NlogMemoryTarget _Target;

    public MainWindow ()
    {
        InitializeComponent ();

        this.Loaded += (s, e) => {
            _Target = new NlogMemoryTarget ("text box output", LogLevel.Trace);
            _Target.Log += log => LogText (log);
        };
    }

    private void LogText (string message)
    {
        this.Dispatcher.Invoke ((Action) delegate () {
            this.MessageView.AppendText (message + "\n");
            this.MessageView.ScrollToEnd ();
        });
    }
}

Answer 2

While this not really answer your question, but i believe this solution is better. An wpf control used to show NLog logs in listview. https://github.com/erizet/NlogViewer.

Answer 3

I agree that the 2 referenced links in the question are not optimal. (I also would NOT use those solutions.)

Here's what I'd try:

Write a custom (WPF) control target using an algorithm similar to NLog's FormControlTarget.

Ensure to register your new target.
Also, NLog's FormHelper may be helpful.

Most of the WinForms code should be easily convertible to WPF.