Appengine with Go: Is there a http.Handle prehook or something similar?

Question

Suppose I have the following init function routing requests.

func init() {
    http.HandleFunc("/user", handler1)
    http.HandleFunc("/user/profile", handler2)
    http.HandleFunc("/user/post", handler3)
    ....
    ....
}

All of these require that I have the user's profile.

I know I can

func handler1(w http.ResponseWriter, r *http.Request) {
    getUserdata()
    //Actual handler code
    ...
    ...
}

But, is there a way I can get the data without putting the function call in every handler? Is this even something Go would want you to do in the first place?

Answer 1

You have two options.

1. You can inplement the http.Handler interface
2. You Wrap all your http.HandlerFunc with a wrapper HandleFunc.

Since it looks like you want something simple I'll illustrate the WRapper

func Prehook(f http.HandlerFunc) http.HandlerFunc {
  return func(w http.ResponseWriter, r *http.Request) {
    getUserData()
    f(w, r)
  }
}

func init() {
    // use getUserData() call before your handler
    http.HandleFunc("/user", Prehook(handler1))
    // Don't use getUserData call before your handler
    http.HandleFunc("/user/profile", handler2)
}