Using log4net as a class library? - c#

I'm working with a console application with c#, visual studio 2008, .net framework 3.5, windows 7. I've created a log4net library and plan to use it on several projects on my solution.
This is how my log4net library class looks like:
public class LibraryLogClass1
{
private static readonly ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
public static void Method3(string message)
{
log.Debug(message);
}
}
In my main console project I have this:
class Program
{
static void Main(string[] args)
{
LibraryLog3.LibraryLogClass1.Method3("test3");
}
}
I've added this line in my AssemblyInfo.cs in my console project:
[assembly: log4net.Config.XmlConfigurator(Watch = true)]
This is my App.config in my console project:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,Log4net"/>
</configSections>
<log4net>
<root>
<level value="DEBUG"/>
<appender-ref ref="LogFileAppender" />
</root>
<appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender" >
<file value="C:\test3.txt"/>
<appendToFile value="true" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="5" />
<maximumFileSize value="10MB" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%d [%t] %-5p %c %m%n" />
</layout>
</appender>
</log4net>
</configuration>
When I ran the program the file is not created.
How can I solve this?
thanks

If you look at the log4net documentation for assembly attributes it says this:
"Therefore if you use configuration attributes you must invoke log4net
to allow it to read the attributes. A simple call to LogManager.GetLogger will cause the attributes on the calling assembly
to be read and processed. Therefore it is imperative to make a logging call as early as possible during the application start-up, and
certainly before any external assemblies have been loaded and invoked."
In your case, your call to Method3 is loading the library assembly, so the static field is attempting to load attributes from the library log class, where the attributes aren't defined.
I generally have something like this at the start of my main program:
LogManager.GetLogger("Initialise log4net from the current assembly attributes");

Related

log4net is not logging anything nor creating the file

I'm trying to configure log4net in my WPF application but I'm struggling to do so. I have read all the questions about it here but none resolved my issue. Find the code down below.
log4net NuGet version: 2.0.8
AssemblyInfo.cs
using System.Windows;
[assembly: ThemeInfo(
ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
//(used if a resource is not found in the page,
// or application resource dictionaries)
ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
//(used if a resource is not found in the page,
// app, or any theme specific resource dictionaries)
)]
[assembly: log4net.Config.XmlConfigurator(Watch = true)]
App.config
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
<log4net>
<appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender">
<param name="File" value="C:\Mylogs\Installer.log" />
<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
<appendToFile value="true" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="10" />
<maximumFileSize value="1MB" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %level %logger - %message%newline" />
</layout>
</appender>
<root>
<level value="ALL" />
<appender-ref ref="LogFileAppender" />
</root>
</log4net>
</configuration>
MainWindow.xaml.cs
using log4net;
...
public partial class MainWindow
{
...
private static readonly ILog Log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
...
private void BtnChangeLocation_Click(object sender, RoutedEventArgs e)
{
...
Log.Debug("This is a Debug message");
Log.Info("This is a Info message");
Log.Warn("This is a Warning message");
Log.Error("This is an Error message");
Log.Fatal("This is a Fatal message");
}
}
When I run the application and click on the button (BtnChangeLocation_Click) no file is created, or even if I create the file manually, nothing is inserted into it. What could be the problem?
I'd suggest to read this: Log4net Tutorial.
There you'll find 14 steps to do to properly install and configure log4Net NuGet package.
One of the most important steps to do is to add log4net.config file, then to add an entry to AssemblyInfo.cs file... Follow the link for further details.
Good luck!

Log4Net not working in MVC web application but working in console and window application

I have created a solution which consist of class library, MVC web application and console application.
For my class library project is actually responsible to perform logging using log4net which is also included the log4net configuration in the log4net.config. Currently i am facing a problem which the logging is not working when my web application call the logging function from class library. But it's working fine when my console application. My log4net.config looks as below:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<log4net>
<appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="C:\\Temp\" />
<datePattern value="'Test.log_'yyyy-MM-dd'.log'" />
<appendToFile value="true" />
<rollingStyle value="Date" />
<appendToFile value="true" />
<staticLogFileName value="false" />
<layout type="log4net.Layout.PatternLayout, log4net">
<conversionPattern value="%date [%thread] %-5level %logger [%method] - %message%newline" />
</layout>
</appender>
<root>
<level value="INFO" />
<appender-ref ref="RollingLogFileAppender" />
</root>
</log4net>
</configuration>
I have also included the line below in my class library [AssemblyInfo.cs]
[assembly: log4net.Config.XmlConfigurator(ConfigFile = "log4net.config", Watch = true)]
My sample class library function as below:
private static readonly log4net.ILog log =
log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
public void Write ()
{
log.Info("Success");
}
I have set the log4net.config Copy to Output Directory to Copy always.
Sample log4net output from console application [Test.log_yyyy-MM-dd.log]:
2019-10-01 12:07:48,923 [1] INFO ClassLibrary2.Class1 [Write] - Success
But there is log file generated for MVC web application. Is there any additional step need to configure for the web application?
I would be grateful for any help with it.
Thanks.
Did you add something in your Application_Start method? (global.asax) like:
string l4net = Server.MapPath("~/log4net.config");
log4net.Config.XmlConfigurator.ConfigureAndWatch(new System.IO.FileInfo(l4net));
Try To Add ConfigSections in your web.config. Also there's the guide especially for MVC applications.
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
Complete Guide

Cannot get Log4net to work from Class Library

I have a class library that performs a routine needed for installation. From everything I have researched, I believe I have things set up correctly. However, the routine absolutely will not log anything. Here is what I have:
I have added the class library project as a reference to the host project.
In my class library, I have the following:
private static readonly ILog Log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
public InstallDLL() {
Log.Error("Where are you goinng?");
}
In the host application, I have added the following line to the AssemblyInfo.cs class: [assembly: log4net.Config.XmlConfigurator(Watch = true)]
Finally, this is the content of my app.config file:
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,Log4net"/>
</configSections>
<log4net>
<appender name="TestAppender" type="log4net.Appender.RollingFileAppender" >
<file value=".\Log Directory\MyTestAppender.log" />
<encoding value="utf-8" />
<appendToFile value="true" />
<rollingStyle value="Date" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="5" />
<maximumFileSize value="2MB" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %-5level %logger [%M %C] - %message%newline" />
</layout>
</appender>
<root>
<level value="ALL" />
<!-- If the following line is not included the log file will not be created even if log4net is configured with this file. -->
<appender-ref ref="TestAppender" />
</root>
</log4net>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
</startup>
</configuration>
I have to be missing something, but what? Keep in mind that logging works fine from the host application...
**** EDIT ********************************************************************
I think I may know what is going on here. The .dll file produced by this project runs BEFORE the host project runs because it is part of the installation script. I think the host project has to run first to initialize the log4net configurations. When I call the method in the .dll file FROM the host application, and not from the installer package, the log4net logging works just fine. Does anyone know if this is root cause, and how I can get around this?
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />, Can you check your Target Framework in Assembly properties?
I just compared with my config file, I have this <log4net debug="true">. Could you please add this?

Log4Net not logging (probably not initialised)

First time playing with Log4Net and I'm running into trouble. I've followed various tutorials but I've been unable to get it to log anything out. Let me show you my code and hopefully you can tell me what I'm doing wrong.
app.config
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="log4net"
type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
<log4net>
<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="CurrentLog.txt"/>
<staticLogFileName value="true"/>
<appendToFile value="true"/>
<rollingStyle value="Date" />
<datePattern value="yyyyMMdd"/>
<filter type="log4net.Filter.LevelRangeFilter">
<acceptOnMatch value="true" />
<levelMin value="DEBUG" />
<levelMax value="FATAL" />
</filter>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date{dd MMM yyy HH:mm:ss} %level %message. %newline %exception" />
</layout>
</appender>
<root>
<level value="ALL" />
<appender-ref ref="RollingFileAppender" />
</root>
</log4net>
</configuration>
AssemblyInfo.cs
[assembly: log4net.Config.XmlConfigurator(Watch=true)]
Presenter.cs
At the top of the class I have this:
private static readonly ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
Then I try to use the log variable later in the class:
bool isDebugEnabled = log.IsDebugEnabled;
log.Debug("Failed to save", e);
Whenever I inspect the isDebugEnabled variable, it is false, as are all of the other isBlahEnabled if I inspect the log variable.
My suspicion is that I have not hooked up my app.config file correctly because this is the first time I have tried to use one. I created by right clicking on the project in solution explorer, adding a new item, choosing Application Configuration File and naming it app.config.
This one works for me:
app.config
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
</configSections>
<log4net>
<appender name="Main" type="log4net.Appender.RollingFileAppender">
<file value="${USERPROFILE}\My Documents\MyApp\Logs\Main.log" />
<appendToFile value="false" />
<maximumFileSize value="1GB" />
<maxSizeRollBackups value="3" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date{ABSOLUTE} %-5level %-18logger %message%newline" />
</layout>
</appender>
<root>
<level value="DEBUG" />
<appender-ref ref="Main" />
</root>
</log4net>
</configuration>
Also be sure the build action on app.config is set to None and Copy to output dir is set to "Copy if newer". You can set these settings in the file properties.
Program.cs
public static ILog Log;
static void Main(string[] args)
{
// Setup Logging
log4net.Config.XmlConfigurator.Configure();
Log = LogManager.GetLogger("MyAwesomeApp");
// ...
}
Just to add my 2 cents: I had the same Problem, but I use the above config in separate log4net.config (so I have on all apps the same config), but I simply forgot to set the file property on build 'Copy when newer' (or similar wording, have German Version).
Just to add my 2p in case this helps anyone else searching for a resolution to this problem:
In my case I was using the NServicebus.Logging package in addition to Log4net, and this package contains types with the exact same names as those in Log4net, differing only in the namespace.
Fixing the 'using' statements or fully-qualifying the type names resolved it, but it was very hard to spot the problem.

How to include log4net for a class library?

I want to implement logging function into a class library, which is itself referenced in a webservice. I tried to add app.config and did everything needed, but it seems that when an exception is thrown, log4net simply does nothing.
my app.config
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
</configSections>
<log4net>
<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="D:\\mylogfile.txt" />
<appendToFile value="true" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="5" />
<maximumFileSize value="10MB" />
<staticLogFileName value="true" />
<filter type="log4net.Filter.StringMatchFilter">
<stringToMatch value="test" />
</filter>
<filter type="log4net.Filter.StringMatchFilter">
<stringToMatch value="error" />
</filter>
<filter type="log4net.Filter.DenyAllFilter" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %level %logger - %message%newline%exception" />
</layout>
</appender>
<root>
<level value="INFO"/>
<appender-ref ref="RollingFileAppender"/>
<appender-ref ref="ConsoleAppender" />
</root>
</log4net>
in AssemblyInfo.cs:
[assembly: log4net.Config.XmlConfigurator(ConfigFile = "app.config")]
in LogManager.cs:
private static readonly ILog Log = log4net.LogManager.GetLogger
(MethodBase.GetCurrentMethod().DeclaringType);
public static void WriteLog(Exception ex)
{
Log.Error(ex);
}
Can you please tell me what's wrong? How can I get log4net working for my class library?
Thank you
At runtime, config file is always used from host application, unless declared explicitly. Here in case, web.config is being used not app.cofig. Rather mention some other custom config file name and ensure that file is copied in virtual directory of web service. Also as chibacity said, ensure permission on log file. Better keep it in app_data folder for web service host.
You could use some kind of injection, either you build a simple one like:
public interface ILogger
{
void LogInfo(string message);
.
.
.
}
And then you just inject something that matches that interface, like a wrapper for log4net or such.
But, I think the most correct thing is to not log in the class library. Why I think so is because the library itself is not the application, your web service is so your web service should decide what to log. If you want to log exceptions just don't catch them in the class library and let your web service handle the logging. This will also make it easier to centralize the logging.
Please see my answer to the following question:
Use log4net in SDK
It has a log configuration routine that will construct a complete path to a log4net config file. As you are in a webservice it my not be looking where you expect for "app.config".
Also make sure that you have permission to write to "D:\mylogfile.txt" from your webservice.

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