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c#loggingasp.net-core
Jez
Jez

Reputation: 29983

Logging in .NET Core without DI?

It seems that Microsoft are really trying to shove DI down your throat with .NET Core, and I'm not sure why, but frankly my console app is small and simple and I just don't want to build a whole DI container just to do some simple logging. How can I do logging in .NET Core without using DI? Everything I've read assumed you're going to use .NET Core's built-in logging architecture which obviously requires DI, but there must be a way to just do it without DI using a static variable on the class?

Upvotes: 41

Views: 28908

Answers (4)

noontz
noontz

Reputation: 1987

As per Ilyas and bokibegs comments in Scotts answer here is the currently working code for .NET 5.0:

using Microsoft.Extensions.Logging;

var factory = LoggerFactory.Create(builder => {
    builder.AddConsole();
});

var logger = factory.CreateLogger<T>();

This requires the Microsoft.Extensions.Logging and Microsoft.Extensions.Logging.Console nuget packages.

Upvotes: 24

Wallace
Wallace

Reputation: 17369

Complete example using .NET Core 6 and NLog 4.7.

  1. Run dotnet new console
  2. Run dotnet add package NLog
  3. Create a new text file named NLog.config1.
<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

    <targets>
        <target name="logfile" xsi:type="File" fileName="file.txt" />
        <target name="logconsole" xsi:type="Console" />
    </targets>

    <rules>
        <logger name="*" minlevel="Info" writeTo="logconsole" />
        <logger name="*" minlevel="Debug" writeTo="logfile" />
    </rules>
</nlog>
  1. Add the NLog.config file to your project file.
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <None Include="NLog.config">
      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    </None>
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="NLog" Version="4.7.13" />
  </ItemGroup>
</Project>
  1. Edit the Program.cs file as follows:
var logger = NLog.LogManager.GetCurrentClassLogger();
logger.Info("Program started.");
logger.Info("Program completed.");
  1. Run dotnet run.

Expected Output

> dotnet run
2022-02-08 17:23:37.0430|INFO|Program|Program started.
2022-02-08 17:23:37.0924|INFO|Program|Program completed.

1https://github.com/NLog/NLog/wiki/Tutorial#configure-nlog-targets-for-output

Upvotes: 3

Jez
Jez

Reputation: 29983

What I ended up doing was using NLog but rather than using their .NET Core DI extensions, I just included the main NLog NuGet package, manually creating my own NLog.config file, and followed the tutorial to GetCurrentClassLogger(), creating that as a static member of my class, then directly used that for logging. This is quite a simple setup and has no need for DI. NLog should probably document it better.

Upvotes: 8

Scott Chamberlain
Scott Chamberlain

Reputation: 127543

If you want to do it yourself you will need to instantiate a LoggerFactory instance somewhere and configure what providers you want. Then you just need to call CreateLogger to create a instance or use new Logger<T>(ILoggerFactory) to create a logger.

using Microsoft.Extensions.Logging;

static class MyLogger {

    public static ILoggerFactory LoggerFactory {get;}

    static MyLogger() {
        LoggerFactory = new LoggerFactory();
        LoggerFactory.AddConsole();
    }
}

public MyClass {
    private readonly ILogger _logger = new Logger<MyClass>(MyLogger.LoggerFactory);
}

Upvotes: 12

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