can use the http.Request.PathValue method to read route variables when using go1.22 and above

Author: hidu

.github/workflows/security.yml

@@ -12,7 +12,7 @@ jobs:
   scan:
     strategy:
       matrix:
-        go: ['1.20','1.21']
+        go: ['1.20','1.21','1.22']
       fail-fast: true
     runs-on: ubuntu-latest
     steps:

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
   unit:
     strategy:
       matrix:
-        go: ['1.20','1.21']
+        go: ['1.20','1.21','1.22']
         os: [ubuntu-latest, macos-latest, windows-latest]
       fail-fast: true
     runs-on: ${{ matrix.os }}

.github/workflows/verify.yml

@@ -12,7 +12,7 @@ jobs:
   lint:
     strategy:
       matrix:
-        go: ['1.20','1.21']
+        go: ['1.20','1.21','1.22']
       fail-fast: true
     runs-on: ubuntu-latest
     steps:

README.md

@@ -79,6 +79,14 @@ func ArticlesCategoryHandler(w http.ResponseWriter, r *http.Request) {
 }
 ```
 
+When using Go 1.22 and above, you also can use the `http.Request.PathValue` method to read route variables:
+```go
+func ArticlesCategoryHandler(w http.ResponseWriter, r *http.Request) {
+    w.WriteHeader(http.StatusOK)
+    fmt.Fprintf(w, "Category: %v\n", r.PathValue("category"))
+}
+```
+
 And this is all you need to know about the basic usage. More advanced options are explained below.
 
 ### Matching Routes

doc.go

@@ -62,6 +62,11 @@ this, convert any capturing groups to non-capturing, e.g. change "/{sort:(asc|de
 "/{sort:(?:asc|desc)}". This is a change from prior versions which behaved unpredictably
 when capturing groups were present.
 
+When using Go 1.22 and above, you also can use the `http.Request.PathValue` method to
+read route variables:
+
+	r.PathValue("category")
+
 And this is all you need to know about the basic usage. More advanced options
 are explained below.
 

mux.go

@@ -494,17 +494,36 @@ func requestWithVars(r *http.Request, vars map[string]string) *http.Request {
 	if len(vars) == 0 {
 		return r
 	}
+	var ro any = r
+	if rr, ok := ro.(canSetPathValue); ok {
+		for k, v := range vars {
+			rr.SetPathValue(k, v)
+		}
+	}
 	ctx := context.WithValue(r.Context(), varsKey, vars)
 	return r.WithContext(ctx)
 }
 
+// canSetPathValue is an interface introduced in Go 1.22.0.
+// The http.Request type added methods PathValue and SetPathValue,
+// which are used to handle named path wildcards in URL routes.
+type canSetPathValue interface {
+	SetPathValue(name, value string)
+}
+
 // requestWithRouteAndVars adds the matched route and vars to the request ctx.
 // It saves extra allocations in cloning the request once and skipping the
 //
 //	population of empty vars, which in turn mux.Vars can handle gracefully.
 func requestWithRouteAndVars(r *http.Request, route *Route, vars map[string]string) *http.Request {
 	ctx := context.WithValue(r.Context(), routeKey, route)
 	if len(vars) > 0 {
+		var ro any = r
+		if rr, ok := ro.(canSetPathValue); ok {
+			for k, v := range vars {
+				rr.SetPathValue(k, v)
+			}
+		}
 		ctx = context.WithValue(ctx, varsKey, vars)
 	}
 	return r.WithContext(ctx)

mux_test.go

@@ -2970,17 +2970,28 @@ func TestContextMiddleware(t *testing.T) {
 
 	r := NewRouter()
 	r.Handle("/path/{foo}", withTimeout(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		vars := Vars(r)
-		if vars["foo"] != "bar" {
-			t.Fatal("Expected foo var to be set")
-		}
+		checkRouteVar(t, r, "foo", "bar")
 	})))
 
 	rec := NewRecorder()
 	req := newRequest("GET", "/path/bar")
 	r.ServeHTTP(rec, req)
 }
 
+func checkRouteVar(t *testing.T, r *http.Request, name string, want string) {
+	t.Helper()
+	vars := Vars(r)
+	if vars[name] != want {
+		t.Fatalf("Expected var %s = %q, but got %q", name, want, vars[name])
+	}
+	var ro any = r
+	if rr, ok := ro.(interface{ PathValue(string) string }); ok {
+		if val := rr.PathValue(name); val != want {
+			t.Fatalf("Expected r.PathValue(%s) = %q, but got %q", name, want, val)
+		}
+	}
+}
+
 func TestGetVarNames(t *testing.T) {
 	r := NewRouter()