Routing is how Web API matches a URI to an action. Web API 2 supports a new type of routing, called attribute routing. As the name implies, attribute routing uses attributes to define routes. Attribute routing gives you more control over the URIs in your web API. For example, you can easily create URIs that describe hierarchies of resources.
The earlier style of routing, called convention-based routing, is still fully supported. In fact, you can combine both techniques in the same project.
One advantage of convention-based routing is that templates are defined in a single place, and the routing rules are applied consistently across all controllers. Unfortunately, convention-based routing makes it hard to support certain URI patterns that are common in RESTful APIs. For example, resources often contain child resources: Customers have orders, movies have actors, books have authors, and so forth. It’s natural to create URIs that reflect these relations:
/customers/1/orders
This type of URI is difficult to create using convention-based routing. Although it can be done, the results don’t scale well if you have many controllers or resource types.
With attribute routing, it’s trivial to define a route for this URI. You simply add an attribute to the controller action:
[Route("customers/{customerId}/orders")]
public IEnumerable<Order> GetOrdersByCustomer(int customerId) { ... }Attribute routing for REST APIs
REST APIs should use attribute routing to model the app’s functionality as a set of resources where operations are represented by HTTP verbs.
Attribute routing uses a set of attributes to map actions directly to route templates. The following code is typical for a REST API and is used in the next sample:
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers();
var app = builder.Build();
app.UseHttpsRedirection();
app.UseAuthorization();
app.MapControllers();
app.Run();In the preceding code, MapControllers is called to map attribute routed controllers.
In the following example:
HomeControllermatches a set of URLs similar to what the default conventional route{controller=Home}/{action=Index}/{id?}matches.
public class HomeController : Controller
{
[Route("")]
[Route("Home")]
[Route("Home/Index")]
[Route("Home/Index/{id?}")]
public IActionResult Index(int? id)
{
return ControllerContext.MyDisplayRouteInfo(id);
}
[Route("Home/About")]
[Route("Home/About/{id?}")]
public IActionResult About(int? id)
{
return ControllerContext.MyDisplayRouteInfo(id);
}
}Read more here;
https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/routing?view=aspnetcore-9.0