.NET 6 Improvements MegaThread

[RehanSaeed]

• Update the target framework for your app to net6.0 and update packages to 6.0.0.
• Fix nullable reference type annotation errors
• Look into simplifying API template using Mi.cro API's. How does this work with Swashbuckle?
• Add HTTP/3 support
• dotnet watch now does dotnet watch run by default.
• Enable hot reload.

{
  "profiles": {
    "dotnet": {
      "commandName": "Project",
      "hotReloadProfile": "aspnetcore"
    }
  }
}

• Add dotnetRunMessages to launchSettings.json https://github.com/dotnet/sdk/issues/14656.
• Switch to DateOnly and TimeOnly structs Introduce Date and Time only structs dotnet/runtime#49036.
• Use TryGetNonEnumeratedCount for Boxed.Mapping What's new in .NET 6 Preview 4 dotnet/core#6098 (comment).
• Use LoggerMessageAttribute for faster logging performance Add LoggerMessage.Define overload to disable IsEnabled check dotnet/runtime#45290.
• Use ValidateOnStart to validate configuration options on startup Developers can get immediate feedback on validation problems dotnet/runtime#36391.
• Use new app.Use overload Add new Use middleware extension method dotnet/aspnetcore#31784.
• Use new API's to get HTTP headers.
• Use CreateAsyncScope instead of CreateScope.
• Add Open Telemetry Metrics.
• Consider use of <AnalysisMode>AllEnabledByDefault</AnalysisMode>.
• Use IHttpActivityFeature to get the current Activity.
• Add System.Text.Json Source Generators.
• Call configuration.GetRequiredSection("Foo").
• Use ArgumentNullException.ThrowIfNull(foo).
• Use new minimal hosting and ConfigurationManager API for quicker startup.
• Developer exception page is now registered for you.
• Add embedded README in NuGet package.
• Use readonly record instead of record.
• Search for potential const interpolated string usages e.g. static readonly Foo = $"{a}{b}" can be rewritten as const Foo = $"{a}{b}" if both a and b are constants.
• Enable ImplicitUsings.

[VictorioBerra]

Regarding Micro APIS dotnet/aspnetcore#27724

The goal of them seems to be to simplify the boilerplate to make the code more approachable to beginners.

The power of Boxed Templates is that it comes easy to customize and it shows the best practices right out of the box (pun intended). So, if when Micro APIs come out if they lack model binding, validation, filters or any other important features I think we should wait.

They did say:

Improve the endpoint routing APIs to the point that we could make it the default API story in ASP.NET Core

If that ends up being true, and we see support from Swashbuckle, I think that will make it a more compelling argument to move that direction.

[RehanSaeed]

Agreed, lets see what they do.