add example for simple http.Handler wrapper

README.md

@@ -13,7 +13,7 @@
 
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_examples/README.md

@@ -70,7 +70,8 @@
         * Convert net/http Handlers
             * [From func(w http.ResponseWriter, r *http.Request, next http.HandlerFunc)](convert-handlers/negroni-like/main.go)
             * [From http.Handler or http.HandlerFunc](convert-handlers/nethttp/main.go)
-            * [From func(http.HandlerFunc) http.HandlerFunc](convert-handlers/real-usecase-raven/writing-middleware/main.go)
+            * [From func(http.Handler) http.Handler](convert-handlers/wrapper/main.go)
+            * [Convert by your own: sentry/raven middleware](convert-handlers/real-usecase-raven/writing-middleware/main.go)
     * [Rewrite Middleware](routing/rewrite/main.go)
     * [Route State](routing/route-state/main.go)
     * [Remove Route](routing/remove-route/main.go)

_examples/convert-handlers/nethttp/wrapper/main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/kataras/iris/v12"
+)
+
+func main() {
+	app := iris.New()
+
+	httpThirdPartyWrapper := StandardWrapper(Options{
+		Message: "test_value",
+	})
+
+	// This case
+	app.WrapRouter(func(w http.ResponseWriter, r *http.Request, router http.HandlerFunc) {
+		httpThirdPartyWrapper(router).ServeHTTP(w, r)
+		// If was func(http.HandlerFunc) http.HandlerFunc:
+		// httpThirdPartyWrapper(router.ServeHTTP).ServeHTTP(w, r)
+	})
+
+	app.Get("/", index)
+	app.Listen(":8080")
+}
+
+func index(ctx iris.Context) {
+	ctx.Writef("Message: %s\n", ctx.Value(msgContextKey))
+}
+
+type Options struct {
+	Message string
+}
+
+type contextKey uint8
+
+var (
+	msgContextKey contextKey = 1
+)
+
+func StandardWrapper(opts Options) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// ...
+			req := r.WithContext(context.WithValue(r.Context(), msgContextKey, opts.Message))
+			next.ServeHTTP(w, req)
+		})
+	}
+}

core/handlerconv/from_std.go

@@ -32,6 +32,17 @@ func FromStd(handler interface{}) context.Handler {
 		// handlerFunc(w,r, http.HandlerFunc)
 		//
 		return FromStdWithNext(h)
+	case func(http.Handler) http.Handler:
+		panic(fmt.Errorf(`
+			Passed handler cannot be converted directly:
+			- http.Handler(http.Handler)
+			---------------------------------------------------------------------
+			Please use the Application.WrapRouter method instead, example code:
+			app := iris.New()
+			// ...
+			app.WrapRouter(func(w http.ResponseWriter, r *http.Request, router http.HandlerFunc) {
+			    httpThirdPartyHandler(router).ServeHTTP(w, r)
+			})`))
 	default:
 		// No valid handler passed
 		panic(fmt.Errorf(`