.NET Core: Use Minimal APIs for Lightweight HTTP Services – Bits of .NET

.NET Core: Use Minimal APIs for Lightweight HTTP Services

- 26.05.26 - ErcanOPAK

🚀 APIs in 10 Lines of Code

MVC Controllers for simple API? Overkill. Minimal APIs (.NET 6+) create HTTP endpoints with minimal ceremony. Perfect for microservices, simple APIs.

❌ Traditional Controller

[ApiController]
[Route("api/[controller]")]
public class UsersController : ControllerBase
{
    [HttpGet]
    public async Task> Get()
    {
        return await _service.GetAllAsync();
    }
    
    [HttpPost]
    public async Task Post(User user)
    {
        return await _service.CreateAsync(user);
    }
}

✅ Minimal API

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddScoped();

var app = builder.Build();

app.MapGet("/api/users", async (IUserService service) => 
    await service.GetAllAsync());

app.MapPost("/api/users", async (User user, IUserService service) =>
    await service.CreateAsync(user));

app.Run();

// Everything in Program.cs!

🎯 Complete CRUD Example

// GET by ID
app.MapGet("/api/users/{id:int}", async (int id, IUserRepository repo) =>
{
    var user = await repo.GetByIdAsync(id);
    return user is not null ? Results.Ok(user) : Results.NotFound();
});

// PUT update
app.MapPut("/api/users/{id:int}", async (int id, User user, IUserRepository repo) =>
{
    var existing = await repo.GetByIdAsync(id);
    if (existing is null) return Results.NotFound();
    
    user.Id = id;
    await repo.UpdateAsync(user);
    return Results.NoContent();
});

// DELETE
app.MapDelete("/api/users/{id:int}", async (int id, IUserRepository repo) =>
{
    var deleted = await repo.DeleteAsync(id);
    return deleted ? Results.NoContent() : Results.NotFound();
});

🔐 Authentication & Authorization

// Require authentication
app.MapGet("/api/profile", async (HttpContext context) =>
{
    return Results.Ok(new { user = context.User.Identity?.Name });
})
.RequireAuthorization();

// Require specific role
app.MapDelete("/api/users/{id}", async (int id) =>
{
    await repo.DeleteAsync(id);
    return Results.NoContent();
})
.RequireAuthorization("AdminOnly");

💡 Pro Tips

Use route groups: Group related endpoints with MapGroup
Add Swagger: builder.Services.AddEndpointsApiExplorer()
Organize endpoints: Use extension methods for large apps
Add filters: .AddEndpointFilter() for cross-cutting concerns
Use Results: Results.Ok(), Results.NotFound() for typed responses

“Rewrote microservice API from MVC to Minimal APIs. Code reduced from 500 lines across 5 files to 150 lines in Program.cs. Startup time halved. Easier for juniors to understand.”

— .NET Architect

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