RoutePrefix vs Route

Question

I understand that RoutePrefix doesn't add a route to the routing table by itself. On your actions you need to have a Route attribute declared. I am having a hard time finding an authoritative blog/msdn page/ something that states why by defalut RoutePrefix doesn't add a route to the routing table.

Does anyone have an authoritative post that does contain this to be the case, and if so will you let me know whom it is. Thank you very much.

Edit To Clarify my question

DOESN'T WORK

[RoutePrefix("api/Steve")]
public class SteveController : ApiController
{
    public int get(){return 1000000;}
}

Works

[RoutePrefix("api/Steve")]
public class SteveController : ApiController
{
    [Route("")]
    public int get(){return 1000000;}
}

The above scenario works because we explicitly stated that the get action on the SteveController has an empty route. Once we do that the route is added to the RouteTable

The first scenario doesn't work, because just using RoutePrefix doesn't add anything to the route table. RoutePrefix by itself will not generate a route. This seems to be common knowledge, I want to find a trusted source, like official Microsoft documentation, that states why this is.

Answer 1

Route prefixes are associated with routes by design in attribute routing.

It is used to set a common prefix for an entire controller.

If you read the release notes that introduced the feature you may get a better understanding of the subject.

ASP.NET Web API 2

Attribute routing

ASP.NET Web API now supports attribute routing, thanks to a contribution by Tim McCall. With attribute routing you can specify your Web API routes by annotating your actions and controllers like this:

[RoutePrefix("orders")] 
public class OrdersController : ApiController 
{ 
    [Route("{id}")] 
    public Order Get(int id) { } 
    [Route("{id}/approve")] 
    public Order Approve(int id) { } 
} 

Attribute routing gives you more control over the URIs in your web API. For example, you can easily define a resource hierarchy using a single API controller:

public class MoviesController : ApiController 
{ 
    [Route("movies")] 
    public IEnumerable<Movie> Get() { } 
    [Route("actors/{actorId}/movies")] 
    public IEnumerable<Movie> GetByActor(int actorId) { } 
    [Route("directors/{directorId}/movies")] 
    public IEnumerable<Movie> GetByDirector(int directorId) { } 
} 

What's New in ASP.NET Web API 2.1

What's New in ASP.NET Web API 2.2

A really good article on the subject

ASP.NET 5 Deep Dive: Routing

While no expert on the subject, here is my understanding of how this works.

With attribute routing the framework inspects the route attribute on the actions of a controller in order to create route entries to add to the route table. So as long as you are using attribute routing you are going to be using the [RouteAttribute]. Without this attribute the action will default back to convention-based routing. The RoutePrefixAttribute is an extensibility point that allows you more control of how you define your routes/Urls. The release notes say as much.

Other than my understanding and the last link provided, everything else was quoted from MS documentation.