Chi empty http.Request.Body in render.Bind - json

Question

I am using github.com/pressly/chi to build this simple program where I try to decode some JSON from the http.Request.Body:
package main
import (
"encoding/json"
"fmt"
"net/http"
"github.com/pressly/chi"
"github.com/pressly/chi/render"
)
type Test struct {
Name string `json:"name"`
}
func (p *Test) Bind(r *http.Request) error {
err := json.NewDecoder(r.Body).Decode(p)
if err != nil {
return err
}
return nil
}
func main() {
r := chi.NewRouter()
r.Post("/products", func(w http.ResponseWriter, r *http.Request) {
var p Test
// err := render.Bind(r, &p)
err := json.NewDecoder(r.Body).Decode(&p)
if err != nil {
panic(err)
}
fmt.Println(p)
})
http.ListenAndServe(":8080", r)
}
When I don't use render.Bind() (from "github.com/pressly/chi/render"), it works as expected.
However, when I uncomment the line err := render.Bind(r, &p) and I comment the line err := json.NewDecoder(r.Body).Decode(&p), it panics with EOF :
2017/06/20 22:26:39 http: panic serving 127.0.0.1:39696: EOF
and thus the json.Decode() fails.
Am I doing something wrong or is the http.Request.Body is already read somewhere else before render.Bind() is called?

Answer 1

render.Bind's purpose is to perform decode and execute Bind(r) to do post decode operations.
For eg.:
type Test struct {
Name string `json:"name"`
}
func (p *Test) Bind(r *http.Request) error {
// At this point, Decode is already done by `chi`
p.Name = p.Name + " after decode"
return nil
}
If you have to do only JSON decode no other actions needs to be done after decode with respect to decoded values. Just use:
// Use Directly JSON decoder of std pkg
err := json.NewDecoder(r.Body).Decode(&p)
OR
// Use wrapper method from chi DecodeJSON
err := render.DecodeJSON(r.Body, &p)