How to extract the post arguments in go server

Like this:

func handler(w http.ResponseWriter, r *http.Request) {
    r.ParseForm()                     // Parses the request body
    x := r.Form.Get("parameter_name") // x will be "" if parameter is not set
    fmt.Println(x)
}

Quoting from the documentation of http.Request

// Form contains the parsed form data, including both the URL
// field's query parameters and the POST or PUT form data.
// This field is only available after ParseForm is called.
// The HTTP client ignores Form and uses Body instead.
Form url.Values