不知道类型并依赖接口的golang Unmarshal Struct In Function

Question

here is what I need to do and can't find the resource I need in order to do it:

I need to write a generic function that will setup a handler for a MOCK server. This handler will receive a JSON object and have to unMarshall it and compare it to a reference structure and set its status accordingly depending on the correspondence between both object. Here is the trick: we do not know inside the function what is the type of the reference.

<===== Where am I at this point ====> I wrote this function, which doesn't work.

func createHandlerToTestDelete(route string, ref interface{}, received interface{}){
    Servmux.HandleFunc(route,
        func(w http.ResponseWriter, r *http.Request) {
            // recreate a structure from body content
            body, _ := ioutil.ReadAll(r.Body)
            json.Unmarshal(body, &received)

            // comparison between ref and received
            if reflect.DeepEqual(received, ref) {
                w.WriteHeader(http.StatusOK)
            } else {
                w.WriteHeader(http.StatusInternalServerError)
            }
        },
    )
}

here is how I am using it:

ref := MyStruct{...NotEmpty...}
received := MyStruct{}
createHandlerToTestDelete("aRoute", ref, received)

The result is that the server when doing Unmarshal will not care of the original type of the received variable.

Does someone has an idea?

Answer 1

Use reflect.New to create a pointer to a value with the same type as the reference type.

func createHandlerToTestDelete(route string, ref interface{}) {
  t := reflect.TypeOf(ref)
  ServeMux.HandleFunc(route,
    func(w http.ResponseWriter, r *http.Request) {
        v := reflect.New(t)
        if err := json.NewDecoder(r.Body).Decode(v.Interface()); err != nil {
            // handle error
        }
        // v is pointer to value. Get element for correct comparison.
        if reflect.DeepEqual(v.Elem().Interface(), ref) {
            w.WriteHeader(http.StatusOK)
        } else {
            w.WriteHeader(http.StatusInternalServerError)
        }
    },
  )
}