From b84fe99d07f9cb1261950121e8da7133bc645302 Mon Sep 17 00:00:00 2001
From: Arjen Poutsma <poutsmaa@vmware.com>
Date: Fri, 3 Dec 2021 12:00:23 +0100
Subject: [PATCH] Polish "Throw 404 ResponseStatusException when no routes
 found"

See gh-25358
---
 .../web/reactive/function/server/RouterFunctions.java      | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java b/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java
index 8b241f70cd..739fc17a1c 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java
@@ -1248,7 +1248,7 @@ public abstract class RouterFunctions {
 				ServerRequest request = new DefaultServerRequest(exchange, this.strategies.messageReaders());
 				addAttributes(exchange, request);
 				return this.routerFunction.route(request)
-						.switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND)))
+						.switchIfEmpty(createNotFoundError())
 						.flatMap(handlerFunction -> wrapException(() -> handlerFunction.handle(request)))
 						.flatMap(response -> wrapException(() -> response.writeTo(exchange,
 								new HandlerStrategiesResponseContext(this.strategies))));
@@ -1260,6 +1260,11 @@ public abstract class RouterFunctions {
 			attributes.put(REQUEST_ATTRIBUTE, request);
 		}
 
+		private <R> Mono<R> createNotFoundError() {
+			return Mono.defer(() -> Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND,
+					"No matching router function")));
+		}
+
 		private static <T> Mono<T> wrapException(Supplier<Mono<T>> supplier) {
 			try {
 				return supplier.get();