Print/Log full unstructured json from stream in Go - json

Question

I inherited someone else's code for an API and since I'm not familiar with the requests that it's receiving I'm trying to print them or log them so I can see their structure. From what I've read about Go, jsons are decoded with Structs but since I don't know how the requests are received I cant write a struct.
I've tried the following on a basic API but they just print me out an empty map or nothing at all:
func createBook(w http.ResponseWriter, r *http.Request) {
var result map[string]interface{}
_ = json.NewDecoder(r.Body).Decode(&result)
fmt.Println(result)
func createBook(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
var book Book
_ = json.NewDecoder(r.Body).Decode(&book)
buf := new(bytes.Buffer)
buf.ReadFrom(r.Body)
newStr := buf.String()
reader := strings.NewReader(newStr)
writter := os.Stdout
dec := json.NewDecoder(reader)
enc := json.NewEncoder(writter)
for {
var m map[string]interface{}
if err := dec.Decode(&m); err == io.EOF {
break
} else if err != nil {
log.Fatal(err)
}
if err := enc.Encode(&m); err != nil {
log.Println(err)
}
fmt.Println(m)
}
book.ID = strconv.Itoa(rand.Intn(100000000)) // Mock ID - not safe
books = append(books, book)
json.NewEncoder(w).Encode(book)
}
Is there any other way that it would print the received json without me knowing the strut beforehand?

Answer 1

Use json.Unmarshal function
import "bytes"
func createBook(w http.ResponseWriter, r *http.Request) {
var result map[string]interface{}
data :+ StreamToByte(r.Body)
err := json.Unmarshal(data, &result)
if err !=nil{
fmt.Println(err) //better to use log
}else
fmt.Println(result)
}
}
func StreamToByte(stream io.Reader) []byte {
buf := new(bytes.Buffer)
buf.ReadFrom(stream)
return buf.Bytes()
}
Refer :
https://appdividend.com/2020/02/28/golang-how-to-convert-json-to-map-in-go/
https://gist.github.com/dixudx/3989284b142414e10352fde9def5c771