groks/mustlogin.go

## mustlogin.go
package mustlogin

import (
	"appengine"
	"appengine/user"
	"fmt"
	"net/http"
)

func init() {
	http.HandleFunc("/1", MustLogin(loggedIn))
	http.Handle("/2", MustLoginHandler{loggedIn})
	http.Handle("/3", MustLogin3(loggedIn))
}

func loggedIn(w http.ResponseWriter, r *http.Request, u user.User) {
	fmt.Fprintln(w, "<html><body>")
	fmt.Fprintln(w, u.Email)
	url, _ := user.LogoutURL(appengine.NewContext(r), r.URL.String())
	fmt.Fprintln(w, "<br /><a href=\""+url+"\">Log out</a>")
	fmt.Fprintln(w, "</body></html>")
}

// Option 1: Use a closure
func MustLogin(done func(http.ResponseWriter, *http.Request, user.User)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		c := appengine.NewContext(r)
		if u := user.Current(c); u == nil {
			url, _ := user.LoginURL(c, r.URL.String())
			http.Redirect(w, r, url, http.StatusSeeOther)
		} else {
			done(w, r, *u)
		}
	}
}

// Option 2: Use a http.Handler
type MustLoginHandler struct {
	inner func(http.ResponseWriter, *http.Request, user.User)
}

func (h MustLoginHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	if u := user.Current(c); u == nil {
		url, _ := user.LoginURL(c, r.URL.String())
		http.Redirect(w, r, url, http.StatusSeeOther)
	} else {
		h.inner(w, r, *u)
	}
}

// Option 3: An http.Handler does not have to be a struct...
type MustLoginHandler3 func(http.ResponseWriter, *http.Request, u user.User)

func (f MustLoginHandler3) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	if u := user.Current(c); u == nil {
		url, _ := user.LoginURL(c, r.URL.String())
		http.Redirect(w, r, url, http.StatusSeeOther)
	} else {
		f(w, r, *u)
	}
}
	package mustlogin

	import (
	"appengine"
	"appengine/user"
	"fmt"
	"net/http"
	)

	func init() {
	http.HandleFunc("/1", MustLogin(loggedIn))
	http.Handle("/2", MustLoginHandler{loggedIn})
	http.Handle("/3", MustLogin3(loggedIn))
	}

	func loggedIn(w http.ResponseWriter, r *http.Request, u user.User) {
	fmt.Fprintln(w, "<html><body>")
	fmt.Fprintln(w, u.Email)
	url, _ := user.LogoutURL(appengine.NewContext(r), r.URL.String())
	fmt.Fprintln(w, "<br /><a href=\""+url+"\">Log out</a>")
	fmt.Fprintln(w, "</body></html>")
	}

	// Option 1: Use a closure
	func MustLogin(done func(http.ResponseWriter, *http.Request, user.User)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	if u := user.Current(c); u == nil {
	url, _ := user.LoginURL(c, r.URL.String())
	http.Redirect(w, r, url, http.StatusSeeOther)
	} else {
	done(w, r, *u)
	}
	}
	}

	// Option 2: Use a http.Handler
	type MustLoginHandler struct {
	inner func(http.ResponseWriter, *http.Request, user.User)
	}

	func (h MustLoginHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	if u := user.Current(c); u == nil {
	url, _ := user.LoginURL(c, r.URL.String())
	http.Redirect(w, r, url, http.StatusSeeOther)
	} else {
	h.inner(w, r, *u)
	}
	}

	// Option 3: An http.Handler does not have to be a struct...
	type MustLoginHandler3 func(http.ResponseWriter, *http.Request, u user.User)

	func (f MustLoginHandler3) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	if u := user.Current(c); u == nil {
	url, _ := user.LoginURL(c, r.URL.String())
	http.Redirect(w, r, url, http.StatusSeeOther)
	} else {
	f(w, r, *u)
	}
	}