How to set route vars in mux

I want to bind 2 urls to 1 function, like below.

router.HandleFunc("/_Users", controller.AddResource)
router.HandleFunc("/Resources/{resourceName}", controller.AddResource)

the "controller.AddResource" is a global function. the code like below:

function AddResource(req *http.Request, w http.ResponseWriter){
    vars := mux.Vars(req)
    resourceName := vars["resourceName"]
    data = request.Body
    AddDataToResource(resourceName, data)
}

so how can I set the vars(resourceName='_User') in the first router?

Create a handler wrapper that sets the mux var:

type setVarWrapper struct {
    fn func(http.ResponseWriter, *http.Request)
    name string
    value string
}

func (h *setVarWrapper) ServeHTTP(w http.ResponseWriter, r *http.Request) {
   mux.Vars(req)[h.name] = h.value
   h.fn(w, r)
}

Wrap the user controller:

router.Handle("/_Users, &setVarWrapper{fn:controller.AddResource, name:"resourceName", value:"_User"})

A simpler option is to write an AddUser function that calls through to the generic controller:

function addUser(req *http.Request, w http.ResponseWriter){
    mux.Vars(req)["resourceName"] = "_User"
    controller.AddResource(w, req)
}

router.HandleFunc("/_Users", addUser)

Perhaps even simpler is to check for "" in the handler:

function AddResource(req *http.Request, w http.ResponseWriter){
    vars := mux.Vars(req)
    resourceName := vars["resourceName"]
    if resourceName == "" {
       resourceName = "_User"
    }
    data = request.Body
    AddDataToResource(resourceName, data)
}