Using log4net with Autofac

Question

I am trying to use log4net with Autofac. I've pasted this code http://autofac.readthedocs.org/en/latest/examples/log4net.html , and from Program.cs/Main() I am doing

var iocBuilder = new ContainerBuilder();
iocBuilder.RegisterModule(new LoggingModule());
var iocContainer = iocBuilder.Build();

now I would like to try this out immediately (in the next line), writing a simple line to the log file. How should I do it?

I am thinking of something like this

var ls = iocContainer.Resolve<LoggingModule>();
ls.Info("the logging is working");

Thanks a lot

Answer 1

To obtain a ILog, log4net need to know the class that use the logger (LogManager.GetLogger(...)). So, you can't resolve a ILog without a parent class. You have to inject the ILog inside a component.

public class MyComponent
{
     public MyComponent(ILog logger)
     {
          this._logger = logger; 
     }

     private readonly ILog _logger; 

     public void Do()
     { 
          this._logger.Info("Log4net OK");
     }
}

In the application start (Global.asax.cs for Asp.net, MVC):

// ...
log4net.Config.XmlConfigurator.Configure();
// ...
iocBuilder.RegisterModule(new LoggingModule());
iocBuilder.RegisterType<MyComponent>().AsSelf(); 

// ...

MyComponent c = iocContainer.Resolve<MyComponent>();
c.Do(); 

Another solution would be to register an ILog for Object and resolve ILog. In this case, the module is not required.

//In the DI container builder:

log4net.Config.XmlConfigurator.Configure();
/// ...
ContainerBuilder cb = new ContainerBuilder()
cb.Register(c => LogManager.GetLogger(typeof(Object))).As<ILog>();
IContainer container = cb.Build(); 

//In the function where we need to ue the logger:

ILog logger = container.Resolve<ILog>();
logger.Info("log4net OK");