How to do a generic decode with golang - json

Question

I've seen some go code that looks like this :
type userForm struct {
Name string `json:"name" validate:"min=2"`
Surname string `json:"surname" validate:"min=2"`
Phone string `json:"phone" validate:"min=10"`
Email string `json:"email,omitempty" validate:"omitempty,email"`
}
type emailForm struct {
Email string `json:"email" validate:"email"`
}
func decodeUserForm(r *http.Request) (userForm, error) {
var body userForm
d := json.NewDecoder(r.Body)
if err := d.Decode(&body); err != nil {
return body, NewHTTPError(err, 400, "unable to decode user form")
}
return body, validateStruct(body)
}
func decodeEmailForm(r *http.Request) (emailForm, error) {
var body emailForm
d := json.NewDecoder(r.Body)
if err := d.Decode(&body); err != nil {
return body, NewHTTPError(err, 400, "unable to decode email form")
}
return body, validateStruct(body)
}
I find two functions redundant. Is there a simpler way to merge those two into a more generic function? Is it good practice in Go?

Answer 1

func decodeForm(r *http.Request, dst interface{}) error {
if err := json.NewDecoder(r.Body).Decode(dst); err != nil {
return NewHTTPError(err, 400, "unable to decode email form")
}
return validateStruct(dst)
}
Then use it as so:
var body emailForm
if err := decodeForm(r, &body); err != nil {
panic(err)
}