snapshot of https://github.com/go-chi/chi.git (master, 2026-09-15; blobs > 131072B omitted)

middleware/url_format.go

@@ -0,0 +1,77 @@
+package middleware
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"github.com/go-chi/chi/v5"
+)
+
+var (
+	// URLFormatCtxKey is the context.Context key to store the URL format data
+	// for a request.
+	URLFormatCtxKey = &contextKey{"URLFormat"}
+)
+
+// URLFormat is a middleware that parses the url extension from a request path and stores it
+// on the context as a string under the key `middleware.URLFormatCtxKey`. The middleware will
+// trim the suffix from the routing path and continue routing.
+//
+// Routers should not include a url parameter for the suffix when using this middleware.
+//
+// Sample usage for url paths `/articles/1`, `/articles/1.json` and `/articles/1.xml`:
+//
+//	func routes() http.Handler {
+//		r := chi.NewRouter()
+//		r.Use(middleware.URLFormat)
+//
+//		r.Get("/articles/{id}", ListArticles)
+//
+//		return r
+//	}
+//
+//	func ListArticles(w http.ResponseWriter, r *http.Request) {
+//		urlFormat, _ := r.Context().Value(middleware.URLFormatCtxKey).(string)
+//
+//		switch urlFormat {
+//		case "json":
+//			render.JSON(w, r, articles)
+//		case "xml:"
+//			render.XML(w, r, articles)
+//		default:
+//			render.JSON(w, r, articles)
+//		}
+//	}
+func URLFormat(next http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		ctx := r.Context()
+
+		var format string
+		path := r.URL.Path
+
+		rctx := chi.RouteContext(r.Context())
+		if rctx != nil && rctx.RoutePath != "" {
+			path = rctx.RoutePath
+		}
+
+		if strings.Index(path, ".") > 0 {
+			base := strings.LastIndex(path, "/")
+			idx := strings.LastIndex(path[base:], ".")
+
+			if idx > 0 {
+				idx += base
+				format = path[idx+1:]
+
+				if rctx != nil {
+					rctx.RoutePath = path[:idx]
+				}
+			}
+		}
+
+		r = r.WithContext(context.WithValue(ctx, URLFormatCtxKey, format))
+
+		next.ServeHTTP(w, r)
+	}
+	return http.HandlerFunc(fn)
+}