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Code samples migrated to the new minimal hosting model in 6.0

aspnetcore/migration/50-to-60-samples.md

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Code samples migrated to the new minimal hosting model in ASP.NET Core in .NET 6

<!-- This content from https://gist.github.com/davidfowl/0e0372c3c1d895c3ce195ba983b1e03d#differences-in-the-hosting-model -->

This article provides samples of code migrated to ASP.NET Core in .NET 6. ASP.NET Core in .NET 6 uses a new minimal hosting model. For more information, see New hosting model.

Middleware

The following code adds the Static File Middleware to a .NET 5 app:

csharp
public class Startup
{
    public void Configure(IApplicationBuilder app)
    {
        app.UseStaticFiles();
    }
}

The following code adds the Static File Middleware to an ASP.NET Core in .NET 6 app:

[!code-csharp]

WebApplication.CreateBuilder initializes a new instance of the xref:Microsoft.AspNetCore.Builder.WebApplicationBuilder class with preconfigured defaults. For more information, see xref:fundamentals/middleware/index?view=aspnetcore-6.0

Routing

The following code adds an endpoint to an .NET 5 app:

csharp
public class Startup
{
    public void Configure(IApplicationBuilder app)
    {
        app.UseRouting();
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapGet("/", () => "Hello World");
        });
    }
}

In .NET 6, routes can be added directly to the xref:Microsoft.AspNetCore.Builder.WebApplication without an explicit call to xref:Microsoft.AspNetCore.Builder.EndpointRoutingApplicationBuilderExtensions.UseEndpoints%2A or xref:Microsoft.AspNetCore.Builder.EndpointRoutingApplicationBuilderExtensions.UseRouting%2A. The following code adds an endpoint to an ASP.NET Core in .NET 6 app:

[!code-csharp]

Note: Routes added directly to the xref:Microsoft.AspNetCore.Builder.WebApplication execute at the end of the pipeline.

<!-- TODO, uncomment when article is updated for .NET 6 For more information, see <xref:fundamentals/routing?view=aspnetcore-6.0> -->

<a name="ccr"></a>

Change the content root, app name, and environment

ASP.NET Core in .NET 5

csharp
public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .UseContentRoot(Directory.GetCurrentDirectory())
        .UseEnvironment(Environments.Staging)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>()
                      .UseSetting(WebHostDefaults.ApplicationKey,
                                  typeof(Program).Assembly.FullName);
        });

ASP.NET Core in .NET 6

[!code-csharp]

For more information, see xref:fundamentals/index

Change the content root, app name, and environment by environment variables or command line

The following table shows the environment variable and command-line argument used to change the content root, app name, and environment:

featureEnvironment variableCommand-line argument
Application nameASPNETCORE_APPLICATIONNAME--applicationName
Environment nameASPNETCORE_ENVIRONMENT--environment
Content rootASPNETCORE_CONTENTROOT--contentRoot

Add configuration providers

ASP.NET Core in .NET 5

csharp
public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureAppConfiguration(config =>
        {
            config.AddIniFile("appsettings.ini");
        })
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

ASP.NET Core in .NET 6

[!code-csharp]

For detailed information, see File configuration providers in xref:fundamentals/configuration/index?view=aspnetcore-6.0.

Add logging providers

ASP.NET Core in .NET 5

csharp
public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureLogging(logging =>
        {
            logging.AddJsonConsole();
        })
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

ASP.NET Core in .NET 6

[!code-csharp]

For more information, see xref:fundamentals/logging/index?view=aspnetcore-6.0#.

Add services

ASP.NET Core in .NET 5

csharp
public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        // Add the memory cache services
        services.AddMemoryCache();

        // Add a custom scoped service
        services.AddScoped<ITodoRepository, TodoRepository>();
    }
}

ASP.NET Core in .NET 6

[!code-csharp]

For more information, see xref:fundamentals/dependency-injection?view=aspnetcore-6.0#.

<a name="cii"></a>

Customize IHostBuilder or IWebHostBuilder

Customize IHostBuilder

ASP.NET Core in .NET 5

csharp
public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureHostOptions(o => o.ShutdownTimeout = TimeSpan.FromSeconds(30));
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

ASP.NET Core in .NET 6

[!code-csharp]

Customize IWebHostBuilder

ASP.NET Core in .NET 5

csharp
public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            // Change the HTTP server implementation to be HTTP.sys based.
            webBuilder.UseHttpSys()
                      .UseStartup<Startup>();
        });

ASP.NET Core in .NET 6

[!code-csharp]

Change the web root

By default, the web root is relative to the content root in the wwwroot folder. Web root is where the Static File Middleware looks for static files. Web root can be changed by setting the xref:Microsoft.AspNetCore.Builder.WebApplicationOptions.WebRootPath property on xref:Microsoft.AspNetCore.Builder.WebApplicationOptions:

ASP.NET Core in .NET 5

csharp
public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            // Look for static files in webroot.
            webBuilder.UseWebRoot("webroot")
                      .UseStartup<Startup>();
        });

ASP.NET Core in .NET 6

[!code-csharp]

<a name="cdi"></a>

Custom dependency injection (DI) container

The following .NET 5 and .NET 6 samples use Autofac

ASP.NET Core in .NET 5

Program class

csharp
public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .UseServiceProviderFactory(new AutofacServiceProviderFactory())
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

Startup

csharp
public class Startup
{
    public void ConfigureContainer(ContainerBuilder containerBuilder)
    {
    }
}

ASP.NET Core in .NET 6

csharp
var builder = WebApplication.CreateBuilder(args);

builder.Host.UseServiceProviderFactory(new AutofacServiceProviderFactory());

// Register services directly with Autofac here. Don't
// call builder.Populate(), that happens in AutofacServiceProviderFactory.
builder.Host.ConfigureContainer<ContainerBuilder>(builder => builder.RegisterModule(new MyApplicationModule()));

var app = builder.Build();

Access additional services

Startup.Configure can inject any service added via the xref:Microsoft.Extensions.DependencyInjection.IServiceCollection.

ASP.NET Core in .NET 5

csharp
public class Startup
{
    // This method gets called by the runtime. Use this method to add services
    // to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IService, Service>();
    }

    // Anything added to the service collection can be injected into Configure.
    public void Configure(IApplicationBuilder app,
                          IWebHostEnvironment env,
                          IHostApplicationLifetime lifetime,
                          IService service,
                          ILogger<Startup> logger)
    {
        lifetime.ApplicationStarted.Register(() =>
            logger.LogInformation(
                "The application {Name} started in the injected {Service}",
                env.ApplicationName, service));
    }
}

ASP.NET Core in .NET 6

In ASP.NET Core in .NET 6:

[!code-csharp]

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Test with WebApplicationFactory or TestServer

ASP.NET Core in .NET 5

In the following samples, the test project uses TestServer and xref:Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory%601. These ship as separate packages that require explicit reference:

WebApplicationFactory

xml
<ItemGroup>
  <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="{Version}" />
</ItemGroup>

TestServer

xml
<ItemGroup>
  <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="{Version}" />
</ItemGroup>

ASP.NET Core in .NET 5 code

csharp
public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IHelloService, HelloService>();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IHelloService helloService)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseRouting();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapGet("/", async context =>
            {
                await context.Response.WriteAsync(helloService.HelloMessage);
            });
        });
    }
}

With TestServer

csharp
[Fact]
public async Task HelloWorld()
{
    using var host = Host.CreateDefaultBuilder()
        .ConfigureWebHostDefaults(builder =>
        {
            // Use the test server and point to the application's startup
            builder.UseTestServer()
                    .UseStartup<WebApplication1.Startup>();
        })
        .ConfigureServices(services =>
        {
            // Replace the service
            services.AddSingleton<IHelloService, MockHelloService>();
        })
        .Build();

    await host.StartAsync();

    var client = host.GetTestClient();

    var response = await client.GetStringAsync("/");

    Assert.Equal("Test Hello", response);
}

class MockHelloService : IHelloService
{
    public string HelloMessage => "Test Hello";
}

With WebApplicationFactory

csharp
[Fact]
public async Task HelloWorld()
{
    var application = new WebApplicationFactory<Program>()
        .WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                services.AddSingleton<IHelloService, MockHelloService>();
            });
        });

    var client = application.CreateClient();

    var response = await client.GetStringAsync("/");

    Assert.Equal("Test Hello", response);
}

class MockHelloService : IHelloService
{
    public string HelloMessage => "Test Hello";
}

ASP.NET Core in .NET 6

[!code-csharp]

Project file (.csproj)

The project file can contain one of the following:

xml
<ItemGroup>
    <InternalsVisibleTo Include="MyTestProject" />
</ItemGroup>

Or

[assembly: InternalsVisibleTo("MyTestProject")]

An alternative solution is to make the Program class public. Program can be made public with Top-level statements by defining a public partial Program class in the project or in Program.cs:

csharp
var builder = WebApplication.CreateBuilder(args);

// ... Configure services, routes, etc.

app.Run();

public partial class Program { }
csharp
[Fact]
public async Task HelloWorld()
{
    var application = new WebApplicationFactory<Program>()
        .WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                services.AddSingleton<IHelloService, MockHelloService>();
            });
        });

    var client = application.CreateClient();

    var response = await client.GetStringAsync("/");

    Assert.Equal("Test Hello", response);
}

class MockHelloService : IHelloService
{
    public string HelloMessage => "Test Hello";
}

The .NET 5 version and .NET 6 version with the WebApplicationFactory are identical by design.