Where are the using statements/directives in .NET 6

Question

I got up and running with Visual Studio 2022 Preview for a couple of days now.

Got the first shock, there is no Startup.cs. Thats ok, a bit of reading, I know Startup is removed.

Today got another slap. I see no using statements. Here it is.

I just created a brand new .NET 6 web app and as I hover over the WebApplication class, I realized it stays in Microsoft.AspNetCore.Builder namespace. And the generated Program.cs class looks like this.

So where is the using Microsoft.AspNetCore.Builder; statement?

Whats the magic? Why is .net becoming mystical by the day?

The full Program.cs file is as follows.

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddRazorPages();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapRazorPages();

app.Run();

Answer 1

C# 10.0 introduces a new feature called global using directive (global using <fully-qualified-namespace>;) which allows to specify namespaces to be implicitly imported in all files in the compilation. .NET 6 RC1 has this feature enabled by default in new project templates (see <ImplicitUsings>enable</ImplicitUsings> property in your .csproj).

For Microsoft.NET.Sdk.Web next namespaces should be implicitly imported (plus the ones from Microsoft.NET.Sdk):

• System.Net.Http.Json
• Microsoft.AspNetCore.Builder
• Microsoft.AspNetCore.Hosting
• Microsoft.AspNetCore.Http
• Microsoft.AspNetCore.Routing
• Microsoft.Extensions.Configuration
• Microsoft.Extensions.DependencyInjection
• Microsoft.Extensions.Hosting
• Microsoft.Extensions.Logging

UPD

To address your questions in comment:

At the moment of writing the generated file containing default imports will be inside the obj folder named something like ProjectName.GlobalUsings.g.cs.

To modify default imports you can add Using element to your .csproj file. Based on exposed attributes it allows several actions including addition and removal:

<ItemGroup>
    <Using Include="SomeFullyQualifiedNamespace"/>
</ItemGroup>

For just addition you can simply prefix your using directive with global modifier in any file (or create a separate one just for this):

global using SomeFullyQualifiedNamespace;