Created
December 19, 2012 15:12
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Recipe to require that a user log in before reaching an http Handler func, without specifying it in app.yaml (similar to Python App Engine's @login_required decorator)
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| package mustlogin | |
| import ( | |
| "appengine" | |
| "appengine/user" | |
| "fmt" | |
| "net/http" | |
| ) | |
| func init() { | |
| http.HandleFunc("/1", MustLogin(loggedIn)) | |
| http.Handle("/2", MustLoginHandler{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) | |
| } | |
| } |
Thanks for the comments!
Re: formatting -- This appears to be a bug with Gists, it looks fine in Chrome on OSX, terrible in Chrome on Linux... I just copy/pasted this from correctly gofmt'd code :(
Re: error handling on LoginURL -- I wasn't sure how best to handle it, require the user's func to take an error as well? I wouldn't want to panic or write to the response since the downstream user might not want that...
A Handler doesn't need to be a struct: https://gist.github.com/4381796
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It looks like the code needs some gofmt'ing, since some of the lines don't appear to have any indentation.
I like the first option better I think, since it doesn't require an extra struct.
The error from user.LoginURL is ignored, but you might want to handle it.
Could the MustLogin signature be rewritten to return HandlerFunc to clean it up a bit?