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.NET & Visual Studio .NET & Visual Studio

Level-500-Referenz zu .NET 8/9, C#, ASP.NET Core, EF Core, Visual Studio, VS Code, NuGet, Tests, Containerisierung, GitHub Actions und Azure SDKs. Level 500 reference for .NET 8/9, C#, ASP.NET Core, EF Core, Visual Studio, VS Code, NuGet, testing, containerization, GitHub Actions, and Azure SDKs.

.NET 8/9 .NET 8/9
LTS und aktuelle Runtime LTS and current runtime
C# 12+ C# 12+
Records, patterns, primary ctors Records, patterns, primary ctors
ASP.NET Core ASP.NET Core
Web APIs, Blazor, gRPC, SignalR Web APIs, Blazor, gRPC, SignalR
CI/CD CI/CD
GitHub Actions und Azure DevOps GitHub Actions and Azure DevOps
💡 Moderne .NET-Entwicklung ist Plattform-, Paket- und Pipeline-Engineering 💡 Modern .NET development is platform, package, and pipeline engineering

Die produktive Qualität eines .NET-Stacks entsteht aus SDK-Management, C#-Sprachfeatures, Hosting-Modell, Observability, NuGet-Strategie, Testpyramide und reproduzierbarer CI/CD-Pipeline. The production quality of a .NET stack comes from SDK management, C# language features, hosting model, observability, NuGet strategy, test pyramid, and a reproducible CI/CD pipeline.

CLI und Templates CLI and templates

dotnet new/build/run/test/publish dotnet new/build/run/test/publish

C# Sprache C# language

Nullable, records, patterns, LINQ Nullable, records, patterns, LINQ

ASP.NET Core ASP.NET Core

Minimal APIs, Blazor, auth, DI Minimal APIs, Blazor, auth, DI

EF Core EF Core

Migrations, change tracking, performance Migrations, change tracking, performance

Tooling und Delivery Tooling and delivery

Visual Studio, VS Code, NuGet, tests, containers Visual Studio, VS Code, NuGet, tests, containers

.NET SDK, Runtime, CLI und Projektvorlagen .NET SDK, runtime, CLI, and project templates

Befehl / Konzept Command / concept Wofür What for Beispiel Example Hinweis Note
dotnet --info dotnet --info SDKs, Runtimes und Hostinformationen prüfen Check SDKs, runtimes, and host info dotnet --info dotnet --info Basisdiagnose bei Build- oder Runtime-Problemen Baseline diagnostics for build or runtime problems
dotnet new dotnet new Projekt- oder Lösungsgerüst erzeugen Create project or solution scaffolding dotnet new webapi -n Api dotnet new webapi -n Api Template-Optionen mit --help prüfen Review template options with --help
dotnet restore dotnet restore NuGet-Abhängigkeiten auflösen Resolve NuGet dependencies dotnet restore dotnet restore Private feeds und lock files berücksichtigen Account for private feeds and lock files
dotnet build dotnet build Kompiliert den Code Compiles the code dotnet build -c Release dotnet build -c Release Deterministische Builds in CI erzwingen Enforce deterministic builds in CI
dotnet run dotnet run Startet die Anwendung lokal Runs the application locally dotnet run --project src/App dotnet run --project src/App Nur für Dev-Loop, nicht für Production Hosting For dev loop only, not production hosting
dotnet test dotnet test Führt Unit- und Integrationstests aus Runs unit and integration tests dotnet test --collect:"XPlat Code Coverage" dotnet test --collect:"XPlat Code Coverage" Flaky Tests im Pipeline-Design beachten Account for flaky tests in pipeline design
dotnet publish dotnet publish Erzeugt deploybare Artefakte Produces deployable artifacts dotnet publish -c Release -r win-x64 --self-contained false dotnet publish -c Release -r win-x64 --self-contained false RID, trimming und AOT bewusst wählen Choose RID, trimming, and AOT deliberately
global.json global.json Pinnt die SDK-Version Pins the SDK version {"sdk":{"version":"8.0.204"}} {"sdk":{"version":"8.0.204"}} Verhindert unbeabsichtigte SDK-Drifts Prevents accidental SDK drift
CLI CLI 

dotnet new sln -n Contoso.Platform
dotnet new webapi -n Contoso.Api
dotnet new xunit -n Contoso.Api.Tests
dotnet sln add .\Contoso.Api\Contoso.Api.csproj
dotnet sln add .\Contoso.Api.Tests\Contoso.Api.Tests.csproj
dotnet add .\Contoso.Api.Tests\Contoso.Api.Tests.csproj reference .\Contoso.Api\Contoso.Api.csproj

C# Sprachreferenz: moderne Features und Entwurfsmuster C# language reference: modern features and design patterns

Feature Feature Nutzen Value Beispiel Example Hinweis Note
Records Records Wertorientierte DTOs und unveränderliche Modelle Value-oriented DTOs and immutable models public record UserDto(string Id, string Name); public record UserDto(string Id, string Name); Mit with-Ausdrücken und value equality kombinierbar Works with with-expressions and value equality
Primary Constructors Primary constructors Kompakte Initialisierung in Klassen Compact initialization in classes public class Mailer(IOptions<MailSettings> options) { } public class Mailer(IOptions<MailSettings> options) { } Abhängigkeiten klar und sparsam halten Keep dependencies clear and minimal
Nullable Reference Types Nullable reference types Vermeidet NullReference-Fehler früh Avoids NullReference errors early string? name string? name Warnings nicht blind unterdrücken Do not suppress warnings blindly
Pattern Matching Pattern matching Lesbare Typ- und Zustandsprüfungen Readable type and state checks if (result is { IsSuccess: true, Value: var data }) if (result is { IsSuccess: true, Value: var data }) Mit switch expressions sehr mächtig Very powerful with switch expressions
Async/Await Async/await Asynchrone I/O und Skalierung Asynchronous I/O and scalability await db.SaveChangesAsync(); await db.SaveChangesAsync(); ConfigureAwait im Library-Kontext bewusst einsetzen Use ConfigureAwait deliberately in library code
LINQ LINQ Deklarative Datenabfragen Declarative data queries orders.Where(o => o.IsOpen).Select(o => o.Id) orders.Where(o => o.IsOpen).Select(o => o.Id) Deferred execution verstehen Understand deferred execution
Source Generators Source generators Code zur Compile-Zeit erzeugen Generate code at compile time System.Text.Json contexts System.Text.Json contexts Nützlich für Performance und Boilerplate-Reduktion Useful for performance and reducing boilerplate
Collection Expressions Collection expressions Kompaktere Initialisierung More compact initialization int[] values = [1, 2, 3]; int[] values = [1, 2, 3]; Neuere Sprachversion erforderlich Requires a recent language version
C# C# 

public record ApiResult<T>(bool IsSuccess, T? Value, string? Error);

public static string ToBadge(ApiResult<int> result) =>
    result switch
    {
        { IsSuccess: true, Value: > 100 } => "High",
        { IsSuccess: true } => "Normal",
        { Error: not null } => "Failed",
        _ => "Unknown"
    };

ASP.NET Core: Hosting, Middleware, Auth und moderne App-Modelle ASP.NET Core: hosting, middleware, auth, and modern app models

Bereich Area Optionen Options Wann einsetzen When to use Hinweis Note
Minimal APIs Minimal APIs Kompakte Endpoint-Definitionen Compact endpoint definitions Services, micro APIs, internal tools Services, micro APIs, internal tools Mit route groups und filters strukturieren Structure with route groups and filters
Controllers Controllers Attribute routing, filters, conventions Attribute routing, filters, conventions Komplexe APIs und größere Teams Complex APIs and larger teams Geeignet für versionierte API-Flächen Well suited to versioned API surfaces
Razor Pages Razor Pages Serverseitige UI-Seiten Server-side UI pages Backoffice- oder admin-nahe Webapps Back-office or admin-adjacent web apps PageModel-Logik schlank halten Keep PageModel logic lean
Blazor Server Blazor Server Interaktive UI mit Server-State Interactive UI with server state Internal dashboards, fast delivery Internal dashboards, fast delivery SignalR-Connection-Management bedenken Consider SignalR connection management
Blazor WebAssembly Blazor WebAssembly Clientseitige .NET UI Client-side .NET UI Rich SPAs with .NET stack Rich SPAs with .NET stack Payload und API-Security sauber designen Design payload and API security carefully
gRPC gRPC Performante Service-to-Service-Kommunikation High-performance service-to-service communication Internal contracts, streaming Internal contracts, streaming HTTP/2 und tooling constraints beachten Observe HTTP/2 and tooling constraints
SignalR SignalR Realtime Push-Kommunikation Real-time push communication Chats, notifications, dashboards Chats, notifications, dashboards Scale-out und auth token renewal einplanen Plan scale-out and auth token renewal
Microsoft Identity Web Microsoft Identity Web Entra-ID-Auth für Web Apps und APIs vereinfachen Simplifies Entra ID auth for web apps and APIs OpenID Connect, downstream APIs OpenID Connect, downstream APIs Ideal für Graph- oder downstream token acquisition Ideal for Graph or downstream token acquisition
C# C# 

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
    .AddMicrosoftIdentityWebApp(builder.Configuration.GetSection("AzureAd"));

builder.Services.AddAuthorization(options =>
{
    options.AddPolicy("RequireAdmin", policy => policy.RequireRole("Admin"));
});

var app = builder.Build();
app.UseAuthentication();
app.UseAuthorization();
app.MapGet("/healthz", () => Results.Ok(new { status = "ok" }));
app.Run();

Entity Framework Core: Modellierung, Migrations und Performance Entity Framework Core: modeling, migrations, and performance

EF-Core-Thema EF Core topic Beschreibung Description Best Practice Best practice Hinweis Note
DbContext DbContext Unit of Work und Change Tracker Unit of work and change tracker Kurzlebig per request oder operation Keep it short-lived per request or operation Nicht als Singleton registrieren Do not register as singleton
Migrations Migrations Schemaänderungen versionieren Version schema changes Migration review und idempotent scripts Review migrations and generate idempotent scripts Keine Produktionsdatenfixes blind in Migration packen Do not blindly put data fixes into migrations
Compiled Queries Compiled queries Weniger Overhead bei Hot Paths Less overhead on hot paths EF.CompileQuery for critical reads EF.CompileQuery for critical reads Nur bei wirklich heißen Pfaden nötig Needed only for truly hot paths
Split Queries Split queries Reduziert Cartesian explosion bei Includes Reduces cartesian explosion on includes AsSplitQuery() AsSplitQuery() Mehr round trips, aber oft weniger Datenmenge More round trips, but often less data volume
NoTracking NoTracking Schnellere Read-only Queries Faster read-only queries AsNoTracking() AsNoTracking() Für Updates bewusst wieder Tracking aktivieren Re-enable tracking intentionally for updates
Providers Providers SQL Server, PostgreSQL, SQLite, Cosmos DB SQL Server, PostgreSQL, SQLite, Cosmos DB Provider-specific behaviors Provider-specific behaviors SQL-Generierung und Datentypmapping pro Provider validieren Validate SQL generation and type mapping per provider
C# C# 

public class AppDbContext(DbContextOptions<AppDbContext> options) : DbContext(options)
{
    public DbSet<Order> Orders => Set<Order>();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Order>()
            .HasIndex(o => new { o.CustomerId, o.CreatedUtc });
    }
}

Visual Studio, VS Code, NuGet, Tests, Container und CI/CD Visual Studio, VS Code, NuGet, tests, containers, and CI/CD

Bereich Area Wichtige Punkte Key points Werkzeuge Tools Hinweis Note
Visual Studio Visual Studio Community, Professional, Enterprise; Debugging, profiling, Live Share Community, Professional, Enterprise; debugging, profiling, Live Share Diagnostic Tools, Test Explorer, Snapshot Debugger Diagnostic Tools, Test Explorer, Snapshot Debugger Enterprise-Features gegen Lizenzbedarf abgleichen Map enterprise features to license needs
VS Code VS Code Leichter Editor mit C# Dev Kit, tasks.json, launch.json Lightweight editor with C# Dev Kit, tasks.json, launch.json Extensions marketplace, Remote Development Extensions marketplace, Remote Development Für containerisierte und polyglotte Projekte sehr stark Very strong for containerized and polyglot projects
NuGet NuGet Paketquellen, lock files, private feeds, Azure Artifacts Package sources, lock files, private feeds, Azure Artifacts dotnet add package, Package Manager Console dotnet add package, Package Manager Console Supply-chain security und SBOM berücksichtigen Consider supply-chain security and SBOM
Testing Testing xUnit, NUnit, MSTest, Moq, integration testing xUnit, NUnit, MSTest, Moq, integration testing WebApplicationFactory, Testcontainers WebApplicationFactory, Testcontainers Integrationstests auf reale Infrastrukturpfade ausrichten Aim integration tests at realistic infrastructure paths
Containerization Containerization Dockerfile, Compose, .NET Aspire, AKS/Container Apps Dockerfile, Compose, .NET Aspire, AKS/Container Apps Multi-stage builds, distroless images Multi-stage builds, distroless images Trimming, globalization und diagnostics bewusst testen Test trimming, globalization, and diagnostics deliberately
GitHub Actions GitHub Actions Build, test, pack, publish Build, test, pack, publish actions/setup-dotnet, cache, artifacts actions/setup-dotnet, cache, artifacts Secrets, environments und provenance sauber verwalten Manage secrets, environments, and provenance cleanly
Azure SDK Azure SDK Azure.Identity, Storage, Messaging, AI SDKs Azure.Identity, Storage, Messaging, AI SDKs DefaultAzureCredential, BlobServiceClient, ServiceBusClient DefaultAzureCredential, BlobServiceClient, ServiceBusClient Credential chain und retries verstehen Understand the credential chain and retries
YAML YAML 

name: dotnet-ci

on:
  push:
    branches: [ main ]
  pull_request:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-dotnet@v4
        with:
          dotnet-version: '8.0.x'
      - run: dotnet restore
      - run: dotnet build --configuration Release --no-restore
      - run: dotnet test --configuration Release --no-build
Dockerfile Dockerfile 

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY . .
RUN dotnet publish src/Contoso.Api/Contoso.Api.csproj -c Release -o /app/publish

FROM mcr.microsoft.com/dotnet/aspnet:8.0
WORKDIR /app
COPY --from=build /app/publish .
ENTRYPOINT ["dotnet", "Contoso.Api.dll"]