Vb.net – NLog – set the logger level in runtime

loggingnlogvb.net

I'm using the latest NLog v3.1 and have a question on how to set logging level at runtime. I have just one target and logger in my NLog.config file. The logger name = "*" and the minlevel = "Info". I have the following code in a module to declare the logger along with a function GetLoggingLevel which I can pass in the logger name to retrieve it's level. However, how may I set the logging level? Currently I'm having to open the NLog.config XML and modify the minlevel in the XML. Since I have autoReload = "true", it takes affect – but was hoping there was a way to set this using an NLog method/property.

Imports System.Xml
Imports NLog

Module modLogging

Private m_Log As Logger

Public ReadOnly Property Log As Logger
    Get
        If (m_Log Is Nothing) Then
            m_Log = LogManager.GetCurrentClassLogger
        End If
        Return m_Log
    End Get
End Property

Public Sub LogShutdown()
    LogManager.Shutdown()
End Sub

Public Function GetLoggingLevel(ByVal loggerName) As String
    Dim level As String = String.Empty

    If (LogManager.GetLogger(loggerName).IsInfoEnabled) Then
        level = "Info"
    ElseIf (LogManager.GetLogger(loggerName).IsErrorEnabled) Then
        level = "Error"
    ElseIf (LogManager.GetLogger(loggerName).IsDebugEnabled) Then
        level = "Debug"
    End If

    Return (level)
End Function

With this I can easily call Log.Info("some text") or Log.Error("some error"), etc. in my project. I can obtain the current level and show this to the user, but I want the user to be able to change the logging level to either Debug, Info, Error, etc. but I cannot figure out how to set the minlevel in the config file at runtime without loading & modifying the config XML directly. Any help would be appreciated.

Kindest Regards

Best Answer

You can access the LogManager.Configuration.LoggingRules and enable or disable logging for a certain level. For instance, using a small project with a NLog config as :

<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <targets>    
    <target name="consoleDetailed" 
            xsi:type="Console" 
            layout="${message}"/>
  </targets>
  <rules>
    <logger name="*" minlevel="Debug" writeTo="consoleDetailed" />
  </rules>
</nlog>

and a console app like

Sub Main()

    Dim log As Logger = LogManager.GetCurrentClassLogger

    log.Debug("debug message")
    log.Info("info message")

    For Each rule As LoggingRule In LogManager.Configuration.LoggingRules
        rule.DisableLoggingForLevel(LogLevel.Debug)
    Next

    LogManager.ReconfigExistingLoggers()

    log.Debug("debug message") REM This line will not be logged
    log.Info("info message")

    Console.ReadLine()

End Sub

Related Solutions

Log4net vs. Nlog

I was recently tasked to "prototype up some loggin'" for an upcoming project. I didn't have any logging framework experience. I researched, ran through tutorials, made toy apps, etc. on Log4Net, NLog, and Enterprise Library for a few days. Came back 3-4 weeks later and put them together into a cohesive demo. Hopefully some of this is useful to you.

My recommendation for our project is this:

Use a logging facade (e.g. Common.Logging, SimpleLoggingFacade) to avoid direct dependencies.
If we end up using Enterprise Library for other facilities, then use it for Logging, too.
If we end up using something with a dependency on Log4Net, use Log4Net.
If none of the above, use NLog. Which I'd prefer.

That's based on these findings (opinions!):

All 3 frameworks are capable and can do some sophisticated things. We want a quality solution, but frankly don't need ultra high performance or 60 types of event sinks.
All 3 have very similar basic concepts.
Each has its own cool tricks, like really advanced routing, or dynamic log filenames, file truncating, etc.
All 3 are pretty well documented in their own way.
For a complete newb like me, they were all a little awkward initially. No drastic differences here for the basics. I got over it.
When revisiting things a few weeks later, NLog was clearly the easiest to resume. I needed very little brush up on it. With Log4Net, I had to revisit a few online examples to get going. With EntLib, I gave up and did the tutorials all over again from scratch - I was totally lost.
I couldn't figure out how to get EntLib to do some things like log to the database. It might be easy, but it was beyond my time limit.
Log4Net and NLog have a small in-code footprint. EntLib is spammy, but I'd use a facade over it anyway.
I accidentally mis-configured EntLib and it told me at run time. Log4Net didn't. I didn't have an accidental mis-config with NLog.
EntLib comes with a nice looking app.config editor, which you 100% need. NLog has a config file schema so you get "intellisense". Log4Net comes with nada.

So obviously I like NLog so far. Not enough to use it in spite of having another solution available, though.

C# – How to force reload of NLog configuration file

Actually, you've got an error in your code: LogManager.Configuration.Reload() does not change configuration of logger, but loads configuration from NLog.config file, deserializes it and returns LoggingConfiguration as a result.

to restore configuration, you need to do something like this:

LogManager.Configuration = LogManager.Configuration.Reload();
LogManager.ReconfigExistingLoggers();

here is a test example (minLevel in example config = "DEBUG"):

[TestMethod]
        public void Test()
        {
            Logger.Trace("TRACE 1");
            Logger.Debug("DEBUG 1");
            Logger.Warn("WARN 1");

            foreach (LoggingRule rule in LogManager.Configuration.LoggingRules)
            {
                rule.DisableLoggingForLevel(LogLevel.Trace);
                rule.DisableLoggingForLevel(LogLevel.Debug);
            }
            LogManager.ReconfigExistingLoggers();

            Logger.Trace("TRACE 2");
            Logger.Debug("DEBUG 2");
            Logger.Warn("WARN 2");

            // Reconfigure();
            LogManager.Configuration = LogManager.Configuration.Reload();
            LogManager.ReconfigExistingLoggers();

            Logger.Trace("TRACE 3");
            Logger.Debug("DEBUG 3");
            Logger.Warn("WARN 3");
        }

output:

(DEBUG): DEBUG 1
(WARN): WARN 1
// here settings changed
(WARN): WARN 2
//here settings reloaded
(DEBUG): DEBUG 3
(WARN): WARN 3

Best Answer

Related Solutions

Log4net vs. Nlog

C# – How to force reload of NLog configuration file

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