Professional ASP.NET Core Routing architectures

Section 1: Conventional (MapControllerRoute)

Conventional routing is defined once and applies to all controllers. It is best for small to medium enterprise websites.

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");
                        

Section 2: Attribute Routing (The API standard)

Attribute routing gives you 100% fine-grained control over your URLs. It is the gold standard for REST APIs.

[Route("api/v1/[controller]")]
public class OrdersController : ControllerBase {
    [HttpGet("{id:int}")]
    public IActionResult GetOrder(int id) { /* ... */ }
}
                        

Section 3: Custom Constraint Mastery

A senior architect doesn't just use {id:int}. They create custom constraints for business requirements (e.g., verifying a valid product code format).

public class ProductCodeConstraint : IRouteConstraint {
    public bool Match(HttpContext httpContext, IRouter route, string routeKey, RouteValueDictionary values, RouteDirection routeDirection) {
        var value = values[routeKey]?.ToString();
        return Regex.IsMatch(value, "^PC-[0-9]{5}$");
    }
}