Introduction to Web API

ASP.NET Web API is a framework for building HTTP services that can be accessed by a variety of clients.

Basic Controller

[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    private readonly IProductService _service;

    public ProductsController(IProductService service)
    {
        _service = service;
    }

    [HttpGet]
    public async Task<ActionResult<IEnumerable<Product>>> GetProducts()
    {
        var products = await _service.GetProductsAsync();
        return Ok(products);
    }

    [HttpGet("{id}")]
    public async Task<ActionResult<Product>> GetProduct(int id)
    {
        var product = await _service.GetProductAsync(id);
        
        if (product == null)
        {
            return NotFound();
        }

        return product;
    }
}

Key Concepts

1. HTTP Methods
   • GET - Retrieve data
   • POST - Create data
   • PUT - Update data
   • DELETE - Remove data
2. Route Attributes
   • [Route] - Define URL patterns
   • [HttpGet] - Handle GET requests
   • [FromBody] - Read from request body
3. Response Types
   • Ok() - 200 Success
   • NotFound() - 404 Not Found
   • BadRequest() - 400 Bad Request