Desenvolvendo APIs em Go usando Middlewares
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1) HTTP middleware allows running code before and after the main request handler. Middleware can be used for logging, authentication, validation, and other pre- and post-processing of requests. 2) Middleware is added by wrapping the main handler, and middleware can call the next handler or short-circuit the request. 3) The alice package provides a cleaner way to chain multiple middlewares by avoiding nested functions. Middleware can access the request and response and call the next handler.
![O servidor retorna uma response
type ResponseWriter interface {
Header() Header
Write([]byte) (int, error)
WriteHeader(int)
}](https://image.slidesharecdn.com/middlewaresgo-161106214633/85/Desenvolvendo-APIs-em-Go-usando-Middlewares-4-320.jpg)
![func middlewareTwo(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
log.Println("Executing before middlewareTwo")
if r.URL.Path != "/" {
return
}
next.ServeHTTP(w, r)
log.Println("Executing after middlewareTwo")
})
}
func final(w http.ResponseWriter, r *http.Request) {
log.Println("Executing finalHandler")
w.Write([]byte("OK"))
}](https://image.slidesharecdn.com/middlewaresgo-161106214633/85/Desenvolvendo-APIs-em-Go-usando-Middlewares-10-320.jpg)
Desenvolvendo APIs em Go usando Middlewares
- 2. Http Is The Foundation Of The Web
- 3. Um cliente manda uma request r.Method - HTTP method (GET, POST, PUT, PATCH, DELETE etc.) r.URL.Path - Request path (/things/123) r.URL.String() - Full URL r.URL.Query() - Query parameters (q=something&p=2) r.Body - io.ReadCloser of the request body
- 4. O servidor retorna uma response type ResponseWriter interface { Header() Header Write([]byte) (int, error) WriteHeader(int) }
- 5. Middlewares
- 6. Between the request and response Enrico Zimuel HTTP middleware is not for your Domain work. The middleware is a path in to, and out of, the core Domain. Paul M. Jones Run code before and after handler code Mat Ryer
- 8. Exemplos
- 9. func middlewareOne(next http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { log.Println("Executing before middlewareOne") next.ServeHTTP(w, r) log.Println("Executing after middlewareOne") }) }
- 10. func middlewareTwo(next http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { log.Println("Executing before middlewareTwo") if r.URL.Path != "/" { return } next.ServeHTTP(w, r) log.Println("Executing after middlewareTwo") }) } func final(w http.ResponseWriter, r *http.Request) { log.Println("Executing finalHandler") w.Write([]byte("OK")) }
- 11. func main() { finalHandler := http.HandlerFunc(final) http.Handle("/", middlewareOne(middlewareTwo(finalHandler))) http.ListenAndServe(":8000", nil) }
- 13. func main() { finalHandler := http.HandlerFunc(final) chain := alice.New(middlewareOne, middlewareTwo).Then(finalHandler) http.ListenAndServe(":8000", chain) }
- 14. package main import ( "github.com/justinas/alice" "net/http" "planrockr" ) func getCurrentSubscription(w http.ResponseWriter, r *http.Request) { ... } func main() { chain := alice.New(planrockr.Auth, planrockr.GetUserByToken). Then(http.HandlerFunc(getCurrentSubscription)) http.ListenAndServe(":8000", chain) }
- 15. package main import ( "github.com/justinas/alice" "net/http" "planrockr" ) func processEvent(next http.Handler) http.Handler { ... } func main() { chain := alice.New(processEvent, planrockr.ValidateHookData). Then(http.HandlerFunc(planrockr.Enqueue)) http.ListenAndServe(":8000", chain) }