I am using Go Chi with a custom handler function that returns an error.
Ideally I want to write a middleware function that uses my custom handler function and return an error that will eventually need to be handled. I will either handle the error in ServeHTTP or have a middleware function that handles all errors (so I can inject any logger I want).
I will handle the returned error in ServeHTTP. However, I need to have the ability to use a custom/ any logger.
Below is a rough outline of my approach.
// HandlerFunc that returns an error
type HandlerFunc func(w http.ResponseWriter, r *http.Request) error
type customHandler HandlerFunc
func (h customHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
err := h(w, r)
if err != nil {
// TODO: handle errors returned from handler here
}
}
func main() {
r := chi.NewRouter()
r.Method(http.MethodGet, "/", customHandler(func(w http.ResponseWriter, req *http.Request) error {
r.Use(useSomeMiddleware)
// Handler logic ...
// Hander returns an error. This will need to be handled
return errors.New("error from handler")
}))
server := &http.Server{
Addr: fmt.Sprintf("%v:%v", "", "1337"),
Handler: r,
}
err := server.ListenAndServe()
if err != nil {
log.Fatalf("main: starting server: %v", err)
}
}
func useSomeMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Handler logic that could potentially return an error
err := errors.New("handler error")
if err != nil {
// TODO: return error either to serveHTTP to handler or to a new error handler
// middleware function
}
})
}
Update 1.
Ideally I want to write a middleware function that uses my custom handler function and return an error that will eventually need to be handled.
I can return errors from a middleware function that uses my custom handler function quite easily. So I can potentially handler errors in ServeHTTP. However I am still looking into an approach where I can build a new middleware and pass in a logger. Below is what my middleware function looks like.
func useSomeMiddleware(next http.Handler) http.Handler {
return customHandler(func(w http.ResponseWriter, r *http.Request) error {
err := errors.New("use some middleware error")
if err != nil {
return err
}
return nil
})
}
