NLog IValueFormatter do not output any data?

问题

I have the following IValueFormatter :

public class NLogValueFormatter : IValueFormatter
{
    public bool FormatValue(object value, string format, CaptureType captureType, IFormatProvider formatProvider, StringBuilder builder)
    {
        if (value.GetType() == typeof(LogData))
            return false;

        builder.Append(format);
        try
        {
            var myTarget = LogManager.Configuration.FindTargetByName("communicationFileLog");
            myTarget = ((myTarget as NLog.Targets.Wrappers.WrapperTargetBase)?.WrappedTarget) ?? myTarget;
            var jsonLayout = (myTarget as NLog.Targets.TargetWithLayout)?.Layout as NLog.Layouts.JsonLayout;

            if (jsonLayout?.MaxRecursionLimit > 0)
            {
                var jsonSettings = new JsonSerializerSettings() { MaxDepth = jsonLayout?.MaxRecursionLimit };
                using (var stringWriter = new StringWriter())
                {
                    try
                    {
                        using (var jsonWriter = new JsonTextWriterMaxDepth(stringWriter, jsonSettings))
                            JsonSerializer.Create(jsonSettings).Serialize(jsonWriter, value);
                    }
                    catch (Exception) { }
                    builder.Append(stringWriter.ToString());
                }
            }
            else
                value = null;
        }
        catch (Exception ex)
        {
            builder.Append($"Failed to serlize {value.GetType()} : {ex.ToString()}");
        }
        return true;
    }

}

The goal with this is to do a JSON serializationthat I can set depth on.

This line of code is executed at statup :

NLog.Config.ConfigurationItemFactory.Default.ValueFormatter = new NLogValueFormatter();

To log data I got this code :

public void LogCommunication(CallInformation callInfo)
        {
            _comLogger.Log(LogLevel.Info, "ComLogger : {@callInfo}", callInfo);
        }

In Nlog.config I got this :

<logger name="CommunicationLogger" minlevel="Trace" writeto="communicationFileLog"></logger>

<target xsi:type="File"
            name="communicationFileLog"
            fileName="${basedir}/logs/${shortdate}.log"
            maxArchiveDays="5"
            maxArchiveFiles="10">
      <layout xsi:type="JsonLayout" includeAllProperties="true" maxRecursionLimit="1">
      </layout>
    </target>

I can see that the FormatValue is executed but the builder contents seems to never end up in the logfile. I do however get some kind of standard serialization in the file but I dont know where it comes from, meybe the includeAllProperties=true. It is not respecting the maxRecursionLimit anyway.

How do I get the IValurFormatter to put out text to the file instead of the standard one?

Regards

来源：https://stackoverflow.com/questions/61804131/nlog-ivalueformatter-do-not-output-any-data