Get implementing type during ASP.Net core dependency injection

Question

How do I inject the type of a class into one of its dependencies using the built in ASP.Net dependency injection?

In Startup.Configure I have:

services.AddTransient<ILogger>(x => new Logger(???));

And my class takes a Logger instance

public class ExampleController : ControllerBase
{
    public Example(ILogger logger)
    {
        ...
    }
}

The Logger constructor should receive typeof(Example) where I have written "???", except this should work for all classes that receive a logger.

The question is very similar to this but I am using an in-house ILogger interface and Logger class, and not using ninject. I effectively wan't to duplicate ninject's "context.Request.ParentContext.Plan.Type" in the other question.

Answer 1

I'm assuming you're using Microsoft.Extensions.Logging . With that at least, there's no need to register anything . The logging is already set up via the call to CreateDefaultBuilder() in Program.cs . The most you'd need to do is add alternate/additional logging providers, but that's config. You'd never call something like services.AddTransient with ILogger .

Instead, you handle the type param of the ILogger interface via the param you're using to inject it:

public class Example
{
    public Example(ILogger<Example> logger)
    {
        ...
    }
}

You can still store it in a simple ILogger ivar, without a generic type, but the param you're injecting into needs to specify the type param.

Alternatively, if you're looking for something a little more flexible, you can inject ILoggerFactory instead, and then use GetType() to provide the type:

public class Example
{
    private readonly ILogger _logger;

    public Example(ILoggerFactory loggerFactory)
    {
        _logger = _loggerFactory.CreateLogger(GetType())
    }
}

Answer 2

One of available solutions is:

Initialize your logger (NLog, Log4Net, you-name-it) like this:

WebHost.ConfigureLogging((context, builder) => ...init your logger engine here...)

Then, use generic version of ILogger<> instead of just ILogger type:

public class Example
{
    public Example(ILogger<Example> logger)
    {
        ...
    }
}

Hope this helps.