CustomerController.cs

[Produces("application/json")]
[Route("api/Customer")]
public class CustomerController : Controller
{
    private readonly NorthwindSlimContext _context;

    public CustomerController(NorthwindSlimContext context)
    {
        _context = context;
    }

    // GET: api/Customer
    [HttpGet]
    public async Task<IActionResult> GetCustomers()
    {
        var customers = await _context.Customers
            .ToListAsync();
        return Ok(customers);
    }

    // GET: api/Customer/ALFKI
    [HttpGet("{id}")]
    public async Task<IActionResult> GetCustomer([FromRoute] string id)
    {
        var customer = await _context.Customers.SingleOrDefaultAsync(m => m.CustomerId == id);

        if (customer == null)
            return NotFound();
        return Ok(customer);
    }
}