Dotnet Idioms

.NET Idioms and Patterns

.NET 8+ rewards minimal APIs, DI, and async-first design. Idiomatic .NET = clean, performant, cloud-native.

Scope: .NET framework patterns. For C#: @.gemini/skills/csharp-idioms/SKILL.md.

Minimal APIs

1. Minimal APIs for simple endpoints:

   app.MapGet("/api/tasks/{id}", async (string id, ITaskService service) =>
       await service.GetByIdAsync(id) is Task task
           ? Results.Ok(task)
           : Results.NotFound());
   
   app.MapPost("/api/tasks", async (CreateTaskRequest request, ITaskService service) =>
   {
       var task = await service.CreateAsync(request);
       return Results.Created($"/api/tasks/{task.Id}", task);
   });
   

2. Controllers for complex endpoints with filters, model binding, etc.

Entity Framework Core

1. DbContext per request (scoped lifetime).
2. Migrations via CLI:

   dotnet ef migrations add AddTaskPriority
   dotnet ef database update
   

3. AsNoTracking() for read-only queries.
4. Compiled queries for hot paths.

Configuration

1. IOptions<T> pattern for strongly-typed config:

   builder.Services.Configure<DatabaseOptions>(builder.Configuration.GetSection("Database"));
   

2. User secrets for local development, Key Vault for production.

Middleware

1. Custom middleware for cross-cutting concerns (logging, correlation IDs).
2. UseExceptionHandler for global error handling.

Testing

1. xUnit + FluentAssertions:

   [Fact]
   public async Task GetTask_ReturnsOk_WhenExists()
   {
       var client = _factory.CreateClient();
       var response = await client.GetAsync("/api/tasks/1");
       response.StatusCode.Should().Be(HttpStatusCode.OK);
   }
   

2. WebApplicationFactory<T> for integration tests.

3. Respawn for database cleanup.

Formatting and Static Analysis

Related

• C# Idioms @.gemini/skills/csharp-idioms/SKILL.md
• API Design Principles @.gemini/skills/api-design-principles/SKILL.md
• Database Design Principles @.gemini/skills/database-design-principles/SKILL.md