Web Dev in Go 1.22

README.md

Web Dev in Go 1.22

Go 1.22 now ships with an HTTP server multiplexer, so there is no longer a need to include routing libraries like httprouter or chi.

Basic use of http.ServeMux

package main

import (
	"errors"
	"fmt"
	"log"
	"net/http"
	"time"
)

func timeHandler(w http.ResponseWriter, r *http.Request) {
	now := time.Now().Format(time.RFC1123)
	fmt.Fprintf(w, "The time is: %v", now)
}

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /time", timeHandler)

	err := http.ListenAndServe(":3000", mux)
	if err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatalf("Server startup failed: %s", err)
	}
}

Path parameters

package main

import (
	"errors"
	"fmt"
	"log"
	"net/http"
)

func itemHandler(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	fmt.Fprintf(w, "received request for item: %v", id)
}

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /item/{id}", itemHandler)

	err := http.ListenAndServe(":3000", mux)
	if err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatalf("Server startup failed: %s", err)
	}
}

Middleware

package main

import (
	"errors"
	"fmt"
	"log"
	"net/http"
	"time"
)

type Middleware func(handler http.Handler) http.Handler

func CombineMiddleware(middlewares ...Middleware) Middleware {
	return func(next http.Handler) http.Handler {
		for _, mw := range middlewares {
			next = mw(next)
		}
		return next
	}
}

func RequestLogger(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		defer func() {
			log.Println(r.Method, r.URL.Path, time.Since(start))
		}()
		next.ServeHTTP(w, r)
	})
}

func timeHandler(w http.ResponseWriter, r *http.Request) {
	now := time.Now().Format(time.RFC1123)
	fmt.Fprintf(w, "The time is: %v", now)
}

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /time", timeHandler)

	middlewares := CombineMiddleware(
		RequestLogger,
	)

	err := http.ListenAndServe(":3000", middlewares(mux))
	if err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatalf("Server startup failed: %s", err)
	}
}

Subrouting

package main

import (
	"errors"
	"fmt"
	"log"
	"net/http"
	"time"
)

func timeHandler(w http.ResponseWriter, r *http.Request) {
	now := time.Now().Format(time.RFC1123)
	fmt.Fprintf(w, "The time is: %v", now)
}

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /time", timeHandler)
	
	v1 := http.NewServeMux()
	v1.Handle("/v1/", http.StripPrefix("/v1", mux))

	err := http.ListenAndServe(":3000", mux)
	if err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatalf("Server startup failed: %s", err)
	}
}

Testing

Also, you can use httptest to test HTTP request handlers.

Other resources

• video
• video