WebAPI.md

Web API

This example shows how to build an ASP.NET Core Web API with Pure.DI, registering controllers as generated roots while keeping compatibility with the Microsoft service-provider pipeline.

Tip

Controller activation goes through IServiceProvider, so controllers have to be visible as composition roots. Pair .Roots<ControllerBase>() with AddControllersAsServices().

The composition setup file is Composition.cs:

using Pure.DI;
using Pure.DI.MS;
using static Pure.DI.Lifetime;

namespace WebAPI;

partial class Composition : ServiceProviderFactory<Composition>
{
    // IMPORTANT:
    // Only composition roots (regular or anonymous) can be resolved through the `IServiceProvider` interface.
    // These roots must be registered using `Root<>(...)` or `Roots<>()` calls.
    [System.Diagnostics.Conditional("DI")]
    private static void Setup() => DI.Setup()
        .Roots<ControllerBase>()

        .Bind().As(Singleton).To<ClockViewModel>()
        .Bind().To<ClockModel>()
        .Bind().As(Singleton).To<Ticks>()

        // Infrastructure
        .Bind().To<MicrosoftLoggerAdapter<TT>>()
        .Bind().To<CurrentThreadDispatcher>();
}

The composition class inherits from ServiceProviderFactory<T>, where T is the composition class itself. Only registered roots can be resolved through the Microsoft IServiceProvider, which is why controllers are registered with .Roots<ControllerBase>().

The web application entry point is in the Program.cs file:

var builder = WebApplication.CreateBuilder(args);

using var composition = new Composition();

// Uses Composition as an alternative IServiceProviderFactory
builder.Host.UseServiceProviderFactory(composition);

// It is required for controllers to be registered as regular services.
builder.Services.AddMvc().AddControllersAsServices();

The project file looks like this:

<Project Sdk="Microsoft.NET.Sdk.Web">
    ...
    <ItemGroup>
        <PackageReference Include="Pure.DI" Version="2.4.2">
            <PrivateAssets>all</PrivateAssets>
            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
        </PackageReference>
        <PackageReference Include="Pure.DI.MS" Version="2.4.2" />
    </ItemGroup>

</Project>

It contains additional references to NuGet packages:

Pure.DI		DI source code generator
Pure.DI.MS		Add-ons for Pure.DI to work with Microsoft DI