func getArticle(w http.ResponseWriter, r *http.Request) {
// Load article.
if chi.URLParam(r, "articleID") != "1" {
render.Respond(w, r, data.ErrNotFound)
return
}
article := &data.Article{
ID: 1,
Title: "Article #1",
Data: []string{"one", "two", "three", "four"},
CustomDataForAuthUsers: "secret data for auth'd users only",
}
// Simulate some context values:
// 1. ?auth=true simluates authenticated session/user.
// 2. ?error=true simulates random error.
if r.URL.Query().Get("auth") != "" {
r = r.WithContext(context.WithValue(r.Context(), "auth", true))
}
if r.URL.Query().Get("error") != "" {
render.Respond(w, r, errors.New("error"))
return
}
render.Respond(w, r, article)
}
func randomErrorMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
rand.Seed(time.Now().Unix())
// One in three chance of random error.
if rand.Int31n(3) == 0 {
errors := []error{data.ErrUnauthorized, data.ErrForbidden, data.ErrNotFound}
render.Respond(w, r, errors[rand.Intn(len(errors))])
return
}
next.ServeHTTP(w, r)
})
}
func listArticles(w http.ResponseWriter, r *http.Request) {
articles := make(chan *data.Article, 5)
// Load data asynchronously into the channel (simulate slow storage):
go func() {
for i := 1; i <= 10; i++ {
articles <- &data.Article{
ID: i,
Title: fmt.Sprintf("Article #%v", i),
Data: []string{"one", "two", "three", "four"},
CustomDataForAuthUsers: "secret data for auth'd users only",
}
time.Sleep(100 * time.Millisecond)
}
close(articles)
}()
// Start streaming data from the channel.
render.Respond(w, r, articles)
}