How do you set up Gorilla Mux r.Use to return errors down the middleware chain? https://godoc.org/github.com/gorilla/mux#Router.Use
Main.go
r := mux.NewRouter()
r.Use(LoggingFunc)
r.Use(AuthFunc)
Basic middleware
Starts with logging middleware which can catch and handle errors from further down the chain
type HandlerFunc func(w http.ResponseWriter, r *http.Request) error
func LoggingFunc(next HandlerFunc) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Logging middleware
defer func() {
if err, ok := recover().(error); ok {
w.WriteHeader(http.StatusInternalServerError)
}
}()
err := next(w, r)
if err != nil {
// log error
}
})
}
The next middleware handles authentication and returns an error to the logging middleware.
func AuthFunc(next HandlerFunc) HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) error {
if r.GET("JWT") == "" {
return fmt.Errorf("No JWT")
}
return next(w, r)
}
}
I keep getting errors like
cannot use AuthFunc (type func(handlers.HandlerFunc) http.Handler) as type mux.MiddlewareFunc in argument to r.Use
Thanks
According to the mux.Use doc its argument type is MiddlewareFunc which return type is http.Handler not error type. You have to define which return type is http.HandlerFunc
type Middleware func(http.HandlerFunc) http.HandlerFunc
func main() {
r := mux.NewRouter()
// execute middleware from right to left of the chain
chain := Chain(SayHello, AuthFunc(), LoggingFunc())
r.HandleFunc("/", chain)
println("server listening : 8000")
http.ListenAndServe(":8000", r)
}
// Chain applies middlewares to a http.HandlerFunc
func Chain(f http.HandlerFunc, middlewares ...Middleware) http.HandlerFunc {
for _, m := range middlewares {
f = m(f)
}
return f
}
func LoggingFunc() Middleware {
return func(next http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
// Loggin middleware
defer func() {
if _, ok := recover().(error); ok {
w.WriteHeader(http.StatusInternalServerError)
}
}()
// Call next middleware/handler in chain
next(w, r)
}
}
}
func AuthFunc() Middleware {
return func(next http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
if r.Header.Get("JWT") == "" {
fmt.Errorf("No JWT")
return
}
next(w, r)
}
}
}
func SayHello(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, "Hello client")
}
It will execute the LogginFunc then AuthFunc and then SayHello method which is your desire method after passing all those middlewares.