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go-chi
URL params are not available inside middleware on the root router
When I create a middleware to log the id URL parameter, which exists in the route I request, the value is always empty. I do get a value inside the handler itself
r := chi.NewRouter()
r.Use(func(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
id := chi.URLParam(r, "id")
log.Println(id)
h.ServeHTTP(w, r)
})
})
r.Get("/test/{id}", func(w http.ResponseWriter, r *http.Request) {
id := router.Param(r, "id").String()
io.WriteString(w, id)
})
When I move this code to a Group, the URL param will become available inside the middleware.
r := chi.NewRouter()
r.Group(func(r chi.Router) {
r.Use(func(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
id := chi.URLParam(r, "id")
log.Println(id)
h.ServeHTTP(w, r)
})
})
r.Get("/test/{id}", func(w http.ResponseWriter, r *http.Request) {
id := router.Param(r, "id").String()
io.WriteString(w, id)
})
})
I think this behavior is quite strange and prone to errors
Tested with the latest version (5.0.11)
This behavior is due to the way the chi router handles middleware and route patterns. When you register a middleware using r.Use() at the root level, the middleware is applied to all routes, including routes that do not have any URL parameters. As a result, when the middleware tries to extract the "id" parameter using chi.URLParam(r, "id"), it doesn't find it because the current route doesn't have an "id" parameter.
The behavior you describe would be what I would expect to be the behavior, but the problem is that when I execute an HTTP request for a route which does have an id parameter, it won't be able to find the parameter even though the route does contain a parameter.
mx.URLParams gets populated only at the routeHTTP function which will not get the id param if your middleware is at the top level (* route). Try this instead:
v1Router := chi.NewRouter()
v1Router.Route("/test/{id}", func(r chi.Router) {
r.Use(Middleware)
r.Get("/", handler.getHandler)
r.Patch("/", handler.updateHandler)
r.Delete("/", handler.deleteHandler)
})
Thanks! That works but is super optimal. I need to repeat the middleware call for every endpoint group.
Example:
v1Router := chi.NewRouter()
v1Router.Route("/test/{id}", func(r chi.Router) {
r.Use(Middleware)
r.Get("/", handler.getHandler)
r.Patch("/", handler.updateHandler)
r.Delete("/", handler.deleteHandler)
})
v1Router := chi.NewRouter()
v1Router.Route("/another-test/{id}", func(r chi.Router) {
r.Use(Middleware)
r.Get("/", handler.getHandler)
r.Patch("/", handler.updateHandler)
r.Delete("/", handler.deleteHandler)
})
That is a problem because I want to ensure that the middleware (authZ) is called on every request. Do I miss anything here or is there a better way to get the URL params in the middleware (I need the params to make a call on the authZ).
