How to create a route with optional url var using gorilla mux?

Question

I want to have an optional URL variable in route. I can't seem to find a way using mux package. Here's my current route:

func main() {
    r := mux.NewRouter()
    r.HandleFunc("/view/{id:[0-9]+}", MakeHandler(ViewHandler))
    http.Handle("/", r)
    http.ListenAndServe(":8080", nil)
}

It works when the url is localhost:8080/view/1. I want it to accept even if there's no id so that if I enter localhost:8080/view it'll still work. Thoughts?

Answer 1

Register the handler a second time with the path you want:

r.HandleFunc("/view", MakeHandler(ViewHandler))

Just make sure when you are getting your vars that you check for this case:

vars := mux.Vars(r)
id, ok := vars["id"]
if !ok {
  // directory listing
  return
}
// specific view