It should be
r = r.WithContext(context.WithValue(r.Context(), key, &s))
Using the address of a key was a typo.
On Tuesday, December 22, 2020 at 12:17:01 AM UTC+1 Uli Kunitz wrote:
> I don't think this is a good idea.
>
> I would do something like this.
>
> type mykey struct{}
> var key mykey
>
> r.Use(func(next http.Handler) http.Handler {
> return http.HandlerFunc(func(w http.ResponseWriter, r
> *http.Request) {
> var s string
> r = r.WithContext(context.WithValue(r.Context(),
> &key, &s))
> next.ServeHTTP(w, r)
> if s != "" {
> fmt.Fprint("string %s\n", s)
> }
> })
> })
>
> In the handler itself you must of course get the value by assuming that
> key will always have string pointer. You can then assign a string to the
> pointer, which will be output if its non-nil. Wonder whether you want to
> store a map or a io.Writer as value instead of a single string.
> On Monday, December 21, 2020 at 5:49:54 PM UTC+1 [email protected] wrote:
>
>>
>> Hello,
>>
>> I'm wondering if it is ok to do this ?
>>
>> ////
>> package main
>>
>> import (
>> "context"
>> "fmt"
>> "log"
>> "net/http"
>>
>> "github.com/gorilla/mux"
>> )
>>
>> func main() {
>> addr := "127.0.0.1:8080"
>> r := mux.NewRouter()
>>
>> r.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
>> newReq := r.WithContext(context.WithValue(r.Context(), 0,
>> "bla"))
>> *r = *newReq
>> // set context
>> })
>>
>> r.Use(func(next http.Handler) http.Handler {
>> return http.HandlerFunc(func(w http.ResponseWriter, r
>> *http.Request) {
>> next.ServeHTTP(w, r)
>>
>> ctx := r.Context()
>> v, ok := ctx.Value(0).(string)
>> if !ok {
>> fmt.Println("could not find context
>> value")
>> } else {
>> fmt.Println(v)
>> }
>> })
>> })
>>
>> s := &http.Server{
>> Addr: addr,
>> Handler: r,
>> }
>>
>> if err := s.ListenAndServe(); err != nil && err !=
>> http.ErrServerClosed {
>> log.Fatalf("could not listen on %s : %v", addr, err)
>> }
>> }
>> ////
>>
>
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