Java客户端-Go Http Mux服务器-go方法上的参数为空

Question

I'v got a GO Lang REST API that works normally when I call it from Postman. But, when I try to call a DELETE method with HttpURLConnection parameters are not received by my method.

Request:

_url = new URL(_urlBase+method);
_http = (HttpURLConnection) _url.openConnection();
_http.setRequestMethod(requestType);
_http.setRequestProperty("Accept", "application/json");    
if ((requestType.toUpperCase().equals("POST")) || (requestType.toUpperCase().equals("DELETE"))) 
{
    _http.setRequestProperty("Accept", "application/json"); 

    byte[] postData = params.getBytes( StandardCharsets.UTF_8 );
    int    postDataLength = postData.length;

    _http.setDoOutput( true );
    _http.setInstanceFollowRedirects( false );
    _http.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded"); 
    _http.setRequestProperty( "charset", "utf-8");
    _http.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
    _http.setUseCaches( false );

    try( DataOutputStream wr = new DataOutputStream( _http.getOutputStream())) {
        wr.write( postData );
    }
}

if (_http.getResponseCode() != 200) {
     throw new RuntimeException("Failed : HTTP error code : " + _http.getResponseCode());
}

PS: I've got a three REST APIs in test at this moment. This method just don't pass parameters for GO Lang, using MUX. On Scala and Rails is working fine.

PS: On Go I'm getting parameter from http.Request.FormValue(field).

Go Routes:

r := mux.NewRouter()
r.HandleFunc("/Rest/get", get).Methods("GET")
r.HandleFunc("/Rest/putCity/{city}", putCity).Methods("PUT")
r.HandleFunc("/Rest/updateCity", updateCity).Methods("POST")
r.HandleFunc("/Rest/deleteCity", deleteCity).Methods("DELETE")
http.ListenAndServe(":12345", r)

Method getting parameter:

func deleteCity(w http.ResponseWriter, r *http.Request) {   
    var city string = r.FormValue("city")
}

Thanks for trying to help guys! Regards.

Answer 1

Looking at the implementation of golang's http.Request.ParseForm(), it seems that the form data is not parsed for DELETE requests.

I'd suggest using the identifier of the city to be deleted as request parameter in the URL:

r.HandleFunc("/Rest/deleteCity/{city}", deleteCity).Methods("DELETE")

While you're at it, you could also refactor the whole definition of the routes to be more consistent with standard REST API design patterns, e.g.,

r.HandleFunc("/Rest/cities/", getCities).Methods("GET")
r.HandleFunc("/Rest/cities/{city}", getCity).Methods("GET")
r.HandleFunc("/Rest/cities/{city}", createCity).Methods("POST") // with body
r.HandleFunc("/Rest/cities/{city}", updateCity).Methods("PUT") // with body
r.HandleFunc("/Rest/cities/{city}", deleteCity).Methods("DELETE")

You can use the following snippet to inspect the request. Please note that this should only used for testing purposes and not in a production environment:

func deleteCity(w http.ResponseWriter, r *http.Request) {
    log.Println("deleteCity handler called")
    dump, err := httputil.DumpRequest(r, true)
    if err != nil {
        http.Error(w, fmt.Sprint(err), http.StatusInternalServerError)
        return
    }
    log.Printf("%q
", dump)
    var city string = r.FormValue("city")
    log.Printf("city: %q
", city)
}