How to make nested router

[tieubao]

I want to implement RESTful API. But the following Beego code cannot make it.

POST /events/
GET /events/:slug
GET /events/:id

POST /events/:slug/sessions/
GET /events/:slug/sessions/:id

Please reference to the source code at: https://github.com/dwarvesf/liulo/blob/4def0c9f879dc2d855697952208cc42c3dcdb34b/routers/router.go

package routers

import (
    "github.com/astaxie/beego"
    "github.com/dwarvesf/liulo/controllers"
)

func init() {

    beego.Router("/", &controllers.MainController{})

    ns := beego.NewNamespace("/v1",

        // Authentication
        beego.NSNamespace("/users",
            beego.NSRouter("/sign_up", &controllers.UserController{}, "POST:SignUp"),
            beego.NSRouter("/sign_in", &controllers.UserController{}, "POST:SignIn"),
            beego.NSRouter("/", &controllers.UserController{}, "GET:GetCurrentUser"),
        ),

        // Events
        beego.NSNamespace("/events",
            beego.NSRouter("/", &controllers.EventController{},
                "POST:Post"),
            beego.NSRouter("/:slug", &controllers.EventController{},
                "GET:GetBySlug"),
            beego.NSRouter("/:eventId",
                &controllers.EventController{}, "GET:GetById"),
        ),

        // Sessions
        beego.NSNamespace("/events/:slug:string/sessions",
            beego.NSRouter("/", &controllers.SessionController{},
                "GET:GetAll;POST:Post"),
            beego.NSRouter("/:sessionId",
                &controllers.SessionController{},
                "GET:GetById"),
        ),

        beego.NSNamespace("/events/:slug:string/sessions/:sessionId/questions",
            beego.NSRouter("/", &controllers.QuestionController{},
                "GET:GetAll;POST:Post"),
            beego.NSRouter("/:questionId", &controllers.QuestionController{},
                "GET:GetById"),
        ),
    )

    beego.AddNamespace(ns)
}