LightInject.Microsoft.AspNetCore.Hosting

Enables LightInject to be used as the service container in AspNetCore applications

Note: This package is meant to be used for Asp.Net Core 2.2 applications. For Asp.Net Core > 3.0, the LightInject.Microsoft.Hosting package should be used.

Installing

<PackageReference Include="LightInject.Microsoft.AspNetCore.Hosting" Version="<version>" />

Usage

Enabling LightInject is as simple as calling the UseLightInject method that extends the IWebHostBuilder.

The following sample shows how to do this in a simple web application.

public class Program
{
    public static void Main(string[] args)
    {           
        CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseLightInject()
            .UseStartup<Startup>();
}

Typically in LightInject, we register services in a composition root

public class CompositionRoot : ICompositionRoot
{
    public void Compose(IServiceRegistry serviceRegistry)
    {
        serviceRegistry.Register<IFoo, Foo>();
    }
}
public interface IFoo {}

public class Foo : IFoo {}

By declaring a method named ConfigureContainer we can get access to the IServiceContainer that we in this example use to register our composition root.

public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {          
        }
	    
    	// Use this method to add services directly to LightInject
    	// Important: This method must exist in order to replace the default provider.
        public void ConfigureContainer(IServiceContainer container)
        {
            container.RegisterFrom<CompositionRoot>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {           
        }
    }

Note: Services registered in the ConfigureServices method will also be registered with LightInject

Controllers

By default, controllers are not actually created by LightInject. They are created by the ASP.NET infrastructure and uses LightInject to resolve its dependencies. To enable LightInject to create the controller instances, we need to add the following line.

services.AddMvc().AddControllersAsServices();

Test Services

We can register test/mock services to be used when testing our controllers.

public void ShouldResolveMockedService()
{
    var builder = new WebHostBuilder()
    .UseLightInject()
    .ConfigureTestContainer<IServiceContainer>(c => c.RegisterTransient<IFoo, FooMock>())
    .UseStartup<TestStartup>();

    using (var webHost = builder.Build())
    {
        var foo = webHost.Services.GetRequiredService<IFoo>();
        Assert.IsType<FooMock>(foo);
    }
}

public class FooMock : IFoo { }