获取与http.HandleFunc匹配的当前模式

Question

Is there a way to get the current route that triggered an http.HandleFunc? Maybe something like this?

http.HandleFunc("/foo/", serveFoo)
func serveFoo(rw http.ResponseWriter, req *http.Request) {
    fmt.Println(http.CurrentRoute())
    // Should print "/foo/"
}

The reason I want to get the current route is because I find myself writing code like this often.

if req.URL.Path != "/some-route/" {
    http.NotFound(resp, req)
    return
}
// or
key := req.URL.Path[len("/some-other-route/"):]

It would be nice if the code was a bit more copy-pastable, modular, and DRY like this.

if req.URL.Path != http.CurrentRoute() {
    http.NotFound(resp, req)
    return
}
// or
key := req.URL.Path[http.CurrentRoute():]

This is really just a small thing, so I'd rather not bring a whole other dependency into my project (Gorilla Mux).

Answer 1

It is not possible to get the current route that matched, but it is possible to eliminate the duplicate code in your scenario. Write a handler that checks the path before calling through to another handler:

func HandleFuncExact(mux *http.ServeMux, pattern string, handler func(http.ResponseWriter, *http.Request) {
    mux.HandleFunc(pattern, func(w http.ResponseWriter, r *http.Request) {
        if req.URL.Path != pattern {
            http.NotFound(w, r)
            return
        }
        handler(w, r)
    })
}

In your application, call the wrapper instead of HandlFunc:

HandleFuncExact(http.DefaultServeMux, "/some-route/", serveSomeRoute)

The function serveSomeRoute can assume that the path is exactly "/some-route/".