.NET

TL;DR

What: A free, cross-platform, open-source developer platform for building apps.

Why: Modern C#, high performance, unified platform, excellent tooling, enterprise-ready.

Quick Start

Install: Download from dotnet.microsoft.com

Create Web API:

dotnet new webapi -n MyApi
cd MyApi
dotnet run

Open https://localhost:5001/weatherforecast

Create minimal API:

dotnet new web -n MinimalApi
cd MinimalApi

Edit Program.cs:

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/", () => "Hello World!");
app.MapGet("/users/{id}", (int id) => new { Id = id });

app.Run();

Cheatsheet

Command	Description
dotnet new webapi	Create Web API project
dotnet new web	Create minimal API
dotnet run	Run the application
dotnet build	Build the project
dotnet watch run	Run with hot reload
dotnet add package Name	Add NuGet package
dotnet ef migrations add	Add EF migration

Gotchas

Minimal API

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();
app.UseSwagger();
app.UseSwaggerUI();

app.MapGet("/api/users", () => new[] { "Alice", "Bob" });
app.MapPost("/api/users", (User user) => Results.Created($"/api/users/{user.Id}", user));
app.MapPut("/api/users/{id}", (int id, User user) => Results.Ok(user));
app.MapDelete("/api/users/{id}", (int id) => Results.NoContent());

app.Run();

record User(int Id, string Name);

Controller-based API

[ApiController]
[Route("api/[controller]")]
public class UsersController : ControllerBase
{
    [HttpGet]
    public ActionResult<IEnumerable<User>> GetAll() => Ok(users);

    [HttpGet("{id}")]
    public ActionResult<User> Get(int id) => Ok(user);

    [HttpPost]
    public ActionResult<User> Create(User user) => CreatedAtAction(nameof(Get), new { id = user.Id }, user);
}

Dependency Injection

// Register service
builder.Services.AddScoped<IUserService, UserService>();

// Inject in controller
public class UsersController : ControllerBase
{
    private readonly IUserService _service;

    public UsersController(IUserService service)
    {
        _service = service;
    }
}

Next Steps

• .NET Documentation - Official docs
• ASP.NET Core Tutorials - Web tutorials
• Entity Framework Core - ORM
• .NET YouTube - Video tutorials