What's new in .NET 7 preview /2

aspnetcore/release-notes/aspnetcore-7.0.md

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+---
+title: What's new in ASP.NET Core 7.0
+author: rick-anderson
+description: Learn about the new features in ASP.NET Core 7.0.
+ms.author: riande
+ms.custom: mvc
+ms.date: 10/29/2021
+uid: aspnetcore-7
+---
+# What's new in ASP.NET Core 7.0 preview
+
+This article highlights the most significant changes in ASP.NET Core 7.0 with links to relevant documentation.
+
+## API controllers
+
+### Parameter binding with DI in API controllers
+
+Parameter binding for API controller actions binds parameters through [dependency injection](xref:fundamentals/dependency-injection) when the type is configured as a service. This means it’s no longer required to explicitly apply the [`[FromServices]`](xref:Microsoft.AspNetCore.Mvc.FromServicesAttribute) attribute to a parameter. In the following code, both actions return the time:
+
+[!code-csharp[](~/release-notes/aspnetcore-7/samples/ApiController/Controllers/MyController.cs?name=snippet)]
+
+In rare cases, automatic DI can break apps that have a type in DI that is also accepted in an API controllers action methods. It's not common to have a type in DI and as an argument in an API controller action. To disable automatic binding of parameters, set [DisableImplicitFromServicesParameters](/dotnet/api/microsoft.aspnetcore.mvc.apibehavioroptions.disableimplicitfromservicesparameters?view=aspnetcore-7.0) `= true`:
+
+[!code-csharp[](~/release-notes/aspnetcore-7/samples/ApiController/Program.cs?name=snippet_dis&highlight=8-11)]
+
+In ASP.NET Core 7.0, types in DI are checked at app startup with <xref:Microsoft.Extensions.DependencyInjection.IServiceProviderIsService> to determine if an argument in an API controller action comes from DI or from the other sources.
+
+The new mechanism to infer binding source of API Controller action parameters uses the following rules:
+
+1. A previously specified [`BindingInfo.BindingSource`](xref:Microsoft.AspNetCore.Mvc.ModelBinding.BindingInfo.BindingSource) is never overwritten.
+1. A complex type parameter, registered in the DI container, is assigned [`BindingSource.Services`](xref:Microsoft.AspNetCore.Mvc.ModelBinding.BindingSource.Services).
+1. A complex type parameter, not registered in the DI container, is assigned [`BindingSource.Body`](xref:Microsoft.AspNetCore.Mvc.ModelBinding.BindingSource.Body).
+1. A parameter with a name that appears as a route value in ***any*** route template is assigned [`BindingSource.Path`](xref:Microsoft.AspNetCore.Mvc.ModelBinding.BindingSource.Path).
+1. All other parameters are [`BindingSource.Query`](xref:Microsoft.AspNetCore.Mvc.ModelBinding.BindingSource.Query).
+
+## Minimal APIs
+
+### Filters in Minimal API apps
+
+Minimal API filters allow developers to implement business logic that supports:
+
+* Running code before and after the route handler.
+* Inspecting and modifying parameters provided during a route handler invocation.
+* Intercepting the response behavior of a route handler.
+
+Filters can be helpful in the following scenarios:
+
+* Validating the request parameters and body that are sent to an endpoint.
+* Logging information about the request and response.
+* Validating that a request is targeting a supported API version.
+
+For more information, see <xref:fundamentals/minimal-apis/min-api-filters>
+
+## IIS
+
+### Shadow copying in IIS
+
+Shadow copying app assemblies to the [ASP.NET Core Module (ANCM)](xref:host-and-deploy/aspnet-core-module) for IIS can provide a better end user experience than stopping the app by deploying an [app offline file](xref:host-and-deploy/iis/app-offline).
+
+For more information, see [Shadow copying in IIS](xref:host-and-deploy/iis/advanced?view=aspnetcore-7.0#shadow-copy)

aspnetcore/release-notes/aspnetcore-7/samples/ApiController/ApiController7.csproj

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+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net7.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

aspnetcore/release-notes/aspnetcore-7/samples/ApiController/Controllers/MyController.cs

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+using Microsoft.AspNetCore.Mvc;
+namespace ApiController7.Controllers;
+
+#region snippet
+[Route("[controller]")]
+[ApiController]
+public class MyController : ControllerBase
+{
+    public ActionResult GetWithAttribute([FromServices] IDateTime dateTime) 
+                                                        => Ok(dateTime.Now);
+
+    [Route("noAttribute")]
+    public ActionResult Get(IDateTime dateTime) => Ok(dateTime.Now);
+}
+#endregion

aspnetcore/release-notes/aspnetcore-7/samples/ApiController/Program.cs

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+#define DIS // FIRST DIS MIN
+#if NEVER
+#elif FIRST
+#region snippet1
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddControllers();
+builder.Services.AddSingleton<IDateTime, SystemDateTime>();
+
+var app = builder.Build();
+
+app.MapControllers();
+
+app.Run();
+#endregion
+#elif DIS
+#region snippet_dis
+using Microsoft.AspNetCore.Mvc;
+
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddControllers();
+builder.Services.AddSingleton<IDateTime, SystemDateTime>();
+
+builder.Services.Configure<ApiBehaviorOptions>(options =>
+{
+    options.DisableImplicitFromServicesParameters = true;
+});
+
+var app = builder.Build();
+
+app.MapControllers();
+
+app.Run();
+#endregion
+#elif MIN
+// The following code works in .NET 6, not new to .NET 7
+#region snippet_min
+using Microsoft.AspNetCore.Mvc;
+
+var builder = WebApplication.CreateBuilder(args);
+builder.Services.AddSingleton<IDateTime, SystemDateTime>();
+
+var app = builder.Build();
+
+app.MapGet("/",   (               IDateTime dateTime) => dateTime.Now);
+app.MapGet("/fs", ([FromServices] IDateTime dateTime) => dateTime.Now);
+app.Run();
+#endregion
+#endif
+

aspnetcore/release-notes/aspnetcore-7/samples/ApiController/SystemDateTime.cs

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+public class SystemDateTime : IDateTime
+{
+    public string Now => DateTime.Now.ToString();
+}
+
+public interface IDateTime
+{
+    string Now { get; }
+}

aspnetcore/release-notes/aspnetcore-7/samples/ApiController/appsettings.Development.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

aspnetcore/release-notes/aspnetcore-7/samples/ApiController/appsettings.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}