英文:
Chi empty http.Request.Body in render.Bind
问题
我正在使用github.com/pressly/chi构建这个简单的程序，我尝试从http.Request.Body解码一些JSON：
package mainimport ("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)}
当我不使用render.Bind()（来自"github.com/pressly/chi/render"）时，它按预期工作。
然而，当我取消注释err := render.Bind(r, &p)这一行，并注释掉err := json.NewDecoder(r.Body).Decode(&p)这一行时，它会出现EOF的panic错误：
2017/06/20 22:26:39 http: panic serving 127.0.0.1:39696: EOF
因此，json.Decode()失败了。
我是否做错了什么，或者在调用render.Bind()之前，http.Request.Body已经在其他地方被读取了？
英文:
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 mainimport ("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?
答案1
得分: 4
render.Bind的目的是执行解码并执行Bind(r)以进行解码后的操作。
例如：
type Test struct {Name string `json:"name"`}func (p *Test) Bind(r *http.Request) error {// 此时，`chi`已经完成了解码p.Name = p.Name + " after decode"return nil}
如果您只需要进行JSON解码，而不需要对解码后的值进行其他操作，请使用以下方法之一：
// 使用标准包的JSON解码器err := json.NewDecoder(r.Body).Decode(&p)
或者
// 使用chi的DecodeJSON包装方法err := render.DecodeJSON(r.Body, &p)
英文:
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 pkgerr := json.NewDecoder(r.Body).Decode(&p)
OR
// Use wrapper method from chi DecodeJSONerr := render.DecodeJSON(r.Body, &p)
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