Csharp on queil.net

Get IServiceCollection From Host Builder in .NET 6

Wed, 08 Jun 2022 08:35:29 +0100

Problem ¶

Neither .NET generic host’s HostBuilder nor IHost exposes IServiceCollection. You can resolve services via the IHost.Services property but there is no obvious way of accessing dependency registration metadata.

Solution ¶

It can be done using a custom service provider factory:

public class ExposeServiceCollectionFactory : IServiceProviderFactory<IServiceCollection>
{
    private DefaultServiceProviderFactory _defaultFactory = 
      new DefaultServiceProviderFactory();

    public IServiceCollection? ServiceCollection { get; private set; }

    public IServiceCollection CreateBuilder(IServiceCollection services)
    {
       ServiceCollection = services;
       return _defaultFactory.CreateBuilder(services);
    }

    public IServiceProvider CreateServiceProvider(IServiceCollection containerBuilder)
    {
       return _defaultFactory.CreateServiceProvider(containerBuilder);
    }
}

Then the factory can be used as follows:

var builder = new HostBuilder();
var factory =  new ExposeServiceCollectionFactory();

builder.UseServiceProviderFactory(factory);

// your configuration here

builder.Build();

var services = factory.ServiceCollection;

Console.WriteLine($"Got {services.Count} services here");

Why would you need that ¶

Usually you wouldn’t. It may come handy when you have a library consuming an IServiceCollection but you have lots of extensions methods for IHostBuilder rather than IServiceCollection. This way you can reuse your extension methods and pass the resulting IServiceCollection to the library.

Seamless Debugging of NuGet Packages

Wed, 14 Aug 2019 18:15:52 +0100

Introduction ¶

Sharing and reusing code between developers and teams has always been a serious challenge. Done badly it may gravely impede development and result with mediocre quality. Sharing source code per se has lots of problems on its own. Therefore, virtually every technology stack has a way of distributing versioned binaries instead. NuGet is the standard for sharing binaries in the .NET world. In open-source communities it’s natural to be able to view source code of a binary package. The next step is an ability to debug third-party binaries if debugging symbols are present. This, however, requires the source code to be downloaded and the debugger to be pointed to it. Source Link is an attempt to make the whole experience seamless. Essentially, it works by enriching packages’ metadata with source control specific information which then can be used on debug time to automatically download and display required source code.

Pure Functions in C#

Tue, 27 Nov 2018 08:50:13 +0100

Intro ¶

Having some recent experience with F# I realised some of the functional programming principles could also be successfully used in C#. One could go completely crazy and create/use library like language-ext. However, I would like to focus on the way of writing code rather than utilizing any libraries. The idea I would like to introduce in this article is pure functions.

Pure has no side effects ¶

In a non-functional mindset there is a common misconception that side effects are something unwanted in good code. I guess it comes from the medical definition of side effects¹ where indeed any other than healing effects are undesirable. However, in the functional mindset we define side effects as changes to any external state. External i.e. not exclusively owned by the function. Here are a few examples of side effects:

Finding references in C# code with Roslyn and F#

Tue, 20 Feb 2018 19:58:29 +0000

Introduction ¶

The most of .NET developers use Roslyn (the .NET Compiler) everyday. But apart from compiling code it comes with a versatile APIs used for syntax highlighting, analyzers, navigation tools just to name the most typical ones. I want to show you how to use it in your own tools. This time I want a tiny tool that finds all usages of a class¹ in a solution².

Let’s code ¶

I picked F# as my language of choice for this post. The code is easily translatable to C# though. All the code from the article you can access here.