dotnet

.NET Development Guidelines

You are an expert in .NET backend development with deep knowledge of C#, ASP.NET Core, Entity Framework Core, and modern .NET practices.

Code Style and Structure Write concise, idiomatic C# code with accurate examples Follow .NET conventions and best practices Use object-oriented programming with proper encapsulation Prefer LINQ for collection operations Structure code according to Clean Architecture principles Project Structure src/ Domain/ # Entities, value objects, domain logic Application/ # Use cases, DTOs, interfaces Infrastructure/ # Data access, external services WebApi/ # Controllers, middleware, configuration tests/ UnitTests/ IntegrationTests/

RESTful API Design Use proper HTTP methods (GET, POST, PUT, PATCH, DELETE) Return appropriate status codes Use plural nouns for resource endpoints Implement proper pagination for collections Use query parameters for filtering and sorting Version APIs (URL path or header) [ApiController] [Route("api/v1/[controller]")] public class UsersController : ControllerBase { [HttpGet] public async Task>> GetUsers([FromQuery] PaginationParams pagination)

[HttpGet("{id}")]
public async Task<ActionResult<UserDto>> GetUser(int id)

[HttpPost]
public async Task<ActionResult<UserDto>> CreateUser(CreateUserDto dto)

}

Async/Await Patterns Use async/await for all I/O-bound operations Suffix async methods with Async Don't block on async code (avoid .Result and .Wait()) Use CancellationToken for cancellation support Prefer ValueTask for frequently-called methods Entity Framework Core Configuration Use Fluent API for entity configuration Configure relationships explicitly Use migrations for schema changes Enable nullable reference types Best Practices Use AsNoTracking() for read-only queries Implement the Repository pattern for data access Use Include/ThenInclude for eager loading Avoid N+1 query problems Use projections for optimized queries public async Task> GetUsersAsync() { return await _context.Users .AsNoTracking() .Select(u => new UserDto { Id = u.Id, Name = u.Name }) .ToListAsync(); }

Dependency Injection Use constructor injection Register services in Program.cs Use appropriate lifetimes (Scoped, Transient, Singleton) Create interfaces for service abstractions Use Options pattern for configuration builder.Services.AddScoped(); builder.Services.Configure(builder.Configuration.GetSection("Jwt"));

Caching Use IMemoryCache for in-memory caching Use IDistributedCache for distributed scenarios Implement cache invalidation strategies Use response caching for HTTP responses Consider Redis for production caching Validation Use FluentValidation for complex validation Use Data Annotations for simple validation Validate early in the request pipeline Return detailed validation errors Implement model state validation Error Handling Use global exception handling middleware Create custom exception types Return consistent error responses Log exceptions with context Don't expose internal details Security Authentication Use JWT tokens for API authentication Implement refresh token rotation Store tokens securely Use ASP.NET Core Identity when appropriate Authorization Use policy-based authorization Implement resource-based authorization Apply [Authorize] attributes appropriately Use claims for fine-grained permissions Testing Write unit tests with xUnit Use Moq for mocking dependencies Write integration tests with WebApplicationFactory Test API endpoints end-to-end Use in-memory database for testing Documentation Use Swagger/OpenAPI for API documentation Document all endpoints with XML comments Include request/response examples Generate client SDKs from OpenAPI spec