C# 12 and .NET 8 coding standards including primary constructors, collection expressions, async patterns, null handling, and naming conventions. Use when writing or reviewing .NET 8 code.
These standards ensure consistent, modern C# code across the codebase. Follow these patterns for all .NET 8 development.
Use primary constructors for dependency injection:
// Good - primary constructor
public class TaskService(ITaskRepository repository, ILogger<TaskService> logger)
{
public async Task<TaskItem> GetByIdAsync(Guid id) => await repository.GetByIdAsync(id);
}
// Avoid - traditional constructor
public class TaskService
{
private readonly ITaskRepository _repository;
public TaskService(ITaskRepository repository) => _repository = repository;
}
Use collection expressions for initialization:
// Good
List<string> items = ["one", "two", "three"];
int[] numbers = [1, 2, 3];
// Avoid
var items = new List<string> { "one", "two", "three" };
TaskService, GetAllAsync, IsCompletedAsync: GetByIdAsync, CreateAsynctaskId, pageSizecancellationToken not ctI: ITaskService, ITaskRepository// Good - accepts and passes CancellationToken
public async Task<List<TaskItem>> GetAllAsync(CancellationToken cancellationToken = default)
{
return await repository.GetAllAsync(cancellationToken);
}
// Avoid - no cancellation support
public async Task<List<TaskItem>> GetAllAsync()
{
return await repository.GetAllAsync();
}
In library code, use ConfigureAwait(false):
await repository.GetAllAsync(cancellationToken).ConfigureAwait(false);
In ASP.NET Core controllers/services, it's optional (HttpContext flows automatically).
Enable nullable reference types (already in csproj):
// Explicit nullability
public string? Description { get; set; } // Can be null
public string Title { get; set; } = string.Empty; // Cannot be null
Use pattern matching for null checks:
// Good
if (task is null) return NotFound();
if (task is not null) Process(task);
// Avoid
if (task == null) return NotFound();
Use required modifier for mandatory properties:
public class CreateTaskRequest
{
public required string Title { get; init; }
public string? Description { get; init; }
}
Use init for immutable properties:
public class TaskItem
{
public Guid Id { get; init; }
public required string Title { get; init; }
public DateTime CreatedAt { get; init; } = DateTime.UtcNow;
}
Use records for request/response DTOs:
public record CreateTaskRequest(string Title, string? Description);
public record TaskResponse(Guid Id, string Title, string? Description, bool IsCompleted);
Always use file-scoped namespaces:
// Good
namespace TaskApi.Services;
public class TaskService { }
// Avoid
namespace TaskApi.Services
{
public class TaskService { }
}
Use for single-line implementations:
// Good
public string FullName => $"{FirstName} {LastName}";
public override string ToString() => Title;
// Use block body for multi-line
public async Task<TaskItem?> GetByIdAsync(Guid id)
{
var task = await repository.GetByIdAsync(id);
logger.LogInformation("Retrieved task {Id}", id);
return task;
}