What Response Code to return on a non-supported HTTP Method on REST?

I'm using Gorilla Mux to handle my HTTP routes for my REST API. I'm using the following binding for my API:

r := mux.NewRouter()
r.Host(baseUrl)

api := r.PathPrefix("/api").Subrouter()
api.HandleFunc("/users", APIUsers).Methods("GET", "POST")

http.Handle("/", r)
http.ListenAndServe(":8083", nil)

Then I do a CURL like this:

$ curl -i -X PUT http://127.0.0.1:8083/api/users

The Method APIUsers doesn't get called, as expected. I do get a 200 OK back tho:

HTTP/1.1 200 OK
Date: Tue, 30 Dec 2014 19:03:59 GMT
Content-Length: 0
Content-Type: text/plain; charset=utf-8

Should I do this different with Gorilla to, let's say, bind all failing functions to a designated function? Also I wonder what's the typical HTTP code to return on non-supported functions. I'm a assuming a code in the 400 range, but I'm not sure which to use. I don't want it to be 200 tho, as the request was not "OK".

Any ideas and tips on this subject?

The status code you should return is "405 MethodNotAllowed" or http.StatusMethodNowAllowed in go.

From wikipedia:

> A request was made of a resource using a request method not supported
> by that resource; for example, using GET on a form which requires data
> to be presented via POST, or using PUT on a read-only resource.

http://en.wikipedia.org/wiki/List_of_HTTP_status_codes

You can set a custom NotFoundHandler but that will apply to all unmatched routes.

If you want a specific response returned you have to define the route explicitly.

Example:

func main() {
    r := mux.NewRouter().PathPrefix("/api").Subrouter()

    // custom not found handler used for unmatched routes
    var notFound NotFound
    r.NotFoundHandler = notFound

    r.HandleFunc("/users", APIUsers).Methods("GET", "POST")

    // return 405 for PUT, PATCH and DELETE
    r.HandleFunc("/users", status(405, "GET", "POST")).Methods("PUT", "PATCH", "DELETE")

    http.Handle("/", r)

    http.ListenAndServe(":8083", nil)
}

type NotFound func(w http.ResponseWriter, req *http.Request)

func (NotFound) ServeHTTP(w http.ResponseWriter, req *http.Request) {
    w.WriteHeader(404)
    w.Write([]byte(`{"message": "Not Found"}`))
}

// status is used to set a specific status code
func status(code int, allow ...string) func(w http.ResponseWriter, req *http.Request) {
    return func(w http.ResponseWriter, req *http.Request) {
        w.WriteHeader(code)
        if len(allow) > 0 {
            w.Write([]byte(`Allow: ` + strings.Join(allow, ", ")))
        }
    }
}

func APIUsers(w http.ResponseWriter, req *http.Request) {
    w.Write([]byte("hello"))
}