How to map WebAPI routes correctly

Question

I'm building an API for a Twitter like site using Web API and have trouble with mapping the routes

I have the following actions for the User controller:

public User Get(string firstname, string lastname)
public User Get(Guid id)
public User Friends(Guid id)
public User Followers(Guid id)
public User Favorites(Guid id)

The desired routes and the generated documentation should be:

api/users?firstname={firstname}&lastname={lastname}
api/users/{id}
api/users/{id}/friends
api/users/{id}/followers
api/users/{id}/favorites

In WebApiConfig.cs I have:

config.Routes.MapHttpRoute(
    "2",
    "api/{controller}/{id}",
    new { action = "get", id = RouteParameter.Optional }
);


config.Routes.MapHttpRoute(
     "1",
     "api/{controller}/{id}/{action}"
);

How can I map WebAPI routes correctly?

Answer 1

Given the flexibility you want you should take a look at

Attribute Routing in ASP.NET Web API 2

In WebApiConfig.cs enable attribute routing like

// Web API routes
config.MapHttpAttributeRoutes();

In UserController

Note given the names of actions Friends, Followers and Favorites they imply returning collections rather than single user

[RoutePrefix("api/users")]
public class UserController: ApiController {

    //eg: GET api/users?firstname={firstname}&lastname={lastname}
    [HttpGet]
    [Route("")]
    public User Get([FromUri]string firstname,[FromUri] string lastname) {...}

    //eg: GET api/users/{id}
    [HttpGet]
    [Route("{id:guid}")]
    public User Get(Guid id){...}

    //eg: GET api/users/{id}/friends
    [HttpGet]
    [Route("{id:guid}/friends")]
    public IEnumerable<User> Friends(Guid id){...}

    //eg: GET api/users/{id}/followers
    [HttpGet]
    [Route("{id:guid}/followers")]
    public IEnumerable<User> Followers(Guid id){...}

    //eg: GET api/users/{id}/favorites
    [HttpGet]
    [Route("{id:guid}/favorites")]
    public IEnumerable<User> Favorites(Guid id){...}
}

Answer 2

Routing is order sensitive. The first match always wins. So it is important that you order you routes from most-specific to least-specific.

// All parameters are required, or it won't match.
// So it will only match URLs 4 segments in length
// starting with /api.
config.Routes.MapHttpRoute(
     "1",
     "api/{controller}/{id}/{action}"
);

// Controller is required, id is optional.
// So it will match any URL starting with
// /api that is 2 or 3 segments in length.
config.Routes.MapHttpRoute(
    "2",
    "api/{controller}/{id}",
    new { action = "get", id = RouteParameter.Optional }
);

When your routes are ordered this way, you will get the behavior you expect.