strongly typed context in golang - github.com/gohttp/app

web.go

package main

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

	"github.com/gohttp/app"
	"github.com/gorilla/context"
)

type Context struct {
	Name string
}

type ContextHandler func(w http.ResponseWriter, r *http.Request, ctx *Context)

func (h ContextHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	ctx := context.Get(r, "Context")
	if ctx == nil {
		ctx = NewRequestContext(r)
		context.Set(r, "Context", ctx)
	}
	h(w, r, ctx.(*Context))
}

func NewRequestContext(r *http.Request) *Context {
	return &Context{
		Name: "",
	}
}

func main() {
	a := app.New()

	// example middleware without context using only go builtins
	a.Use(func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			log.Println(r.RequestURI)
			next.ServeHTTP(w, r)
		})
	})

	// example middleware with strongly typed context
	a.Use(func(next http.Handler) http.Handler {
		return ContextHandler(func(w http.ResponseWriter, r *http.Request, ctx *Context) {
			name := r.URL.Query().Get("name")
			if name == "" {
				name = "Guest"
			}

			ctx.Name = name
			next.ServeHTTP(w, r)
		})
	})

	// example route without context using only go builtins
	a.Get("/", func(w http.ResponseWriter, r *http.Request) {
		http.Redirect(w, r, "/hi", http.StatusMovedPermanently)
	})

	// example route using strongly typed context
	a.Get("/hi", ContextHandler(func(w http.ResponseWriter, r *http.Request, ctx *Context) {
		fmt.Fprintf(w, "Hi %s", ctx.Name)
	}))

	a.Listen(":3000")
}

Recommended readings:

• http://www.alexedwards.net/blog/making-and-using-middleware
• http://aarondunnington.com/http-request-context-in-golang
• http://shadynasty.biz/blog/2012/08/07/painless-web-handlers-in-go/
• https://justinas.org/alice-painless-middleware-chaining-for-go/