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Kenichiro Nakamura
Kenichiro Nakamura

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C# : Add Custom Logger to .NET 6 Web API

Even thought .NET 6 Web API template looks different from previous versions, it still works in the same way. In this article, I will explain how to:

  • Use Dependency Injection with .NET 6 Web API template
  • Use Custom Logger

Create new Web API project

1. First thing first. Let's create new Web API project.



dotnet new webapi -n loggerwebapi
cd loggerwebapi
dotnet run


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2. Confirm it works as expected by using any http tool you want. The port number may be different.

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Add Custom Logger

Implement a custom logging provider in .NET has detail information, so simply use this as my custom logger.

I simply added three classes from the article and put it into Logger folder.

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DI

The last step is to add the custom logger via Depedencies Injection. We can do it via Program.cs.

1. Open Program.cs and add following line under // Add services to the container. section.



builder.Services.TryAddEnumerable(
    ServiceDescriptor.Singleton<ILoggerProvider, ColorConsoleLoggerProvider>());
LoggerProviderOptions.RegisterProviderOptions
    <ColorConsoleLoggerConfiguration, ColorConsoleLoggerProvider>(builder.Services);


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2. Add logging code to WeatherForecastController.cs. I added LogInformation to Get method.



[HttpGet(Name = "GetWeatherForecast")]
public IEnumerable<WeatherForecast> Get()
{
    _logger.LogInformation("test");
    return Enumerable.Range(1, 5).Select(index => new WeatherForecast
    {
        Date = DateTime.Now.AddDays(index),
        TemperatureC = Random.Shared.Next(-20, 55),
        Summary = Summaries[Random.Shared.Next(Summaries.Length)]
    })
    .ToArray();
}


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Test

Now, we can run the solution again to see how it works.

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Modify Custom Logger

1. I modified ColorConsoleLoggerConfiguration.cs as follows.



using Microsoft.Extensions.Logging;

public class ColorConsoleLoggerConfiguration
{
    public int EventId { get; set; }

    public Dictionary<LogLevel, ConsoleColor> LogLevels { get; set; } = new()
    {
        [LogLevel.Information] = ConsoleColor.Cyan,
        [LogLevel.Error] = ConsoleColor.DarkRed,
        [LogLevel.Warning] = ConsoleColor.Blue
    };
}


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2. Then I added several more logging code to Get method.



[HttpGet(Name = "GetWeatherForecast")]
public IEnumerable<WeatherForecast> Get()
{
    _logger.LogError("error");
    _logger.LogWarning("warning");
    _logger.LogInformation("info");

    return Enumerable.Range(1, 5).Select(index => new WeatherForecast
    {
        Date = DateTime.Now.AddDays(index),
        TemperatureC = Random.Shared.Next(-20, 55),
        Summary = Summaries[Random.Shared.Next(Summaries.Length)]
    })
    .ToArray();
}


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3. Run the test again.

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Summary

Even though .NET 6 templates looks different due to some simplification with new features, it still works in a same way as previous versions.

It's okay to use old style if we want, but I think it's good to know how to code it in the latest way as well.

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