How to decode query parameter in golang - go

Question

i have parameter
id_user
phone_number
I want to decode to my struct
type User struct{
IDUser int `json:"id_user"`
PhoneNumber string `json:"phone_number"`
}
is it possible to decode into struct? I use gorilla schema. My Code:
func User(w http.ResponseWriter, r *http.Request){
var decoder = schema.NewDecoder()
var user User
if err := r.ParseForm(); err != nil {
fmt.Println(err)
}
err := decoder.Decode(&user, r.PostForm)
if err != nil {
fmt.Println(err)
}
respBody, err := json.Marshal(user)
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(http.StatusOK)
w.Write(respBody)
}
i input id_user = 1 and phone_number = qwerty. But the result is id_user = 0 and phone_number = "".

Answer 1

If your mentioned two fields are query params you can directly read it like this way:
func User(w http.ResponseWriter, r *http.Request) {
idUser := r.URL.Query().Get("id_user")
phoneNumber := r.URL.Query().Get("phone_number")
var user User
id, err := strconv.Atoi(idUser)
if err != nil {
fmt.Println("error converting string to int")
return
}
user.IDUser = id
user.PhoneNumber = phoneNumber
respBody, _ := json.Marshal(user)
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(http.StatusOK)
w.Write(respBody)
}
Otherwise you can directly pass the User struct in api payload and directly do the payLoad decoding like this
if err := json.NewDecoder(r.Body).Decode(&user); err != nil {
fmt.Println("error decoding api payload")
return
}

Answer 2

I think you should fix your tags from this:
type User struct{
IDUser int `json:id_user`
PhoneNumber string `json:phone_number`
}
to this:
type User struct{
IDUser int `json:"id_user"`
PhoneNumber string `json:"phone_number"`
}
So, you should use quotes in tag names.

Answer 3

If you want to decode them directly into a structure without getting the values of the fields one by one then you can use github.com/gorilla/schema. Refer to this question.

Answer 4

This answer may not be suitable for the question since the op was seeking help of using gorilla/schema package.
However, if someone were looking for a package to decode HTTP query params into a struct in Go, I will recommend an awesome package here:
ggicci/httpin
Disclaimer: I'm the creator and maintainer of this package.
httpin helps you easily decoding HTTP request data from
Query parameters, e.g. ?name=john&is_member=true
Headers, e.g. Authorization: xxx
Form data, e.g. username=john&password=******
JSON/XML Body, e.g. POST {"name":"john"}
Path variables, e.g. /users/{username}
File uploads
How to use?
type ListUsersInput struct {
Page int `in:"query=page"`
PerPage int `in:"query=per_page"`
IsMember bool `in:"query=is_member"`
}
func ListUsers(rw http.ResponseWriter, r *http.Request) {
input := r.Context().Value(httpin.Input).(*ListUsersInput)
if input.IsMember {
// Do sth.
}
// Do sth.
}
httpin is:
well documented: at https://ggicci.github.io/httpin/
well tested: coverage over 98%
open integrated: with net/http, go-chi/chi, gorilla/mux, gin-gonic/gin, etc.
extensible (advanced feature): by adding your custom directives. Read httpin - custom directives for more details.
awesome mentioned: https://github.com/avelino/awesome-go#forms