Building a Web API

This lesson pulls together routing, controllers, model binding, and Entity Framework from the earlier lessons into one small, real REST API for managing products.

The full controller

C# Controllers/ProductsController.cs

[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    private readonly AppDbContext _db;
    public ProductsController(AppDbContext db) => _db = db;

    [HttpGet]
    public IActionResult GetAll() =>
        Ok(_db.Products.ToList());

    [HttpGet("{id:int}")]
    public IActionResult GetById(int id)
    {
        var product = _db.Products.Find(id);
        return product is null ? NotFound() : Ok(product);
    }

    [HttpPost]
    public IActionResult Create([FromBody] Product product)
    {
        _db.Products.Add(product);
        _db.SaveChanges();
        return CreatedAtAction(nameof(GetById), new { id = product.Id }, product);
    }

    [HttpDelete("{id:int}")]
    public IActionResult Delete(int id)
    {
        var product = _db.Products.Find(id);
        if (product is null) return NotFound();

        _db.Products.Remove(product);
        _db.SaveChanges();
        return NoContent();
    }
}

Exercising every route

Terminal

curl -X POST http://localhost:5225/api/products \
  -H "Content-Type: application/json" \
  -d '{"name":"Headphones","price":59.99}'

curl http://localhost:5225/api/products
curl http://localhost:5225/api/products/1
curl -X DELETE http://localhost:5225/api/products/1
curl -i http://localhost:5225/api/products/1

Output

{"id":1,"name":"Headphones","price":59.99}
[{"id":1,"name":"Headphones","price":59.99}]
{"id":1,"name":"Headphones","price":59.99}
(204 No Content)
HTTP/1.1 404 Not Found

CreatedAtAction returns a 201 response with a Location header pointing back at the new resource's GetById URL — the correct REST convention for a successful creation, rather than just returning a plain 200. NoContent() is the equally conventional response for a successful delete: the operation worked, and there's nothing left to send back.

Course complete: that covers the ASP.NET Core fundamentals — running a project with the minimal API style, routing requests by method and path, organizing endpoints into controllers, mixing C# into HTML with Razor, binding and validating request data into models, understanding the middleware pipeline requests flow through, and querying a real database with Entity Framework Core. Together these pieces are the shape of most real-world ASP.NET APIs — the next natural steps are authentication (JWT tokens or cookie auth), deploying to a real host, and exploring Blazor if you want to build UI in C# as well.

PreviousEntity Framework Basics