Defer evaluation of right-hand route in composed route

Author: poutsma

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunction.java

@@ -47,7 +47,8 @@ public interface RouterFunction<T extends ServerResponse> {
 	 * @see #andOther(RouterFunction)
 	 */
 	default RouterFunction<T> and(RouterFunction<T> other) {
-		return request -> this.route(request).otherwiseIfEmpty(other.route(request));
+		return request -> this.route(request)
+				.otherwiseIfEmpty(Mono.defer(() -> other.route(request)));
 	}
 
 	/**
@@ -62,7 +63,8 @@ default RouterFunction<T> and(RouterFunction<T> other) {
 	default RouterFunction<?> andOther(RouterFunction<?> other) {
 		return request -> this.route(request)
 				.map(RouterFunctions::cast)
-				.otherwiseIfEmpty(other.route(request).map(RouterFunctions::cast));
+				.otherwiseIfEmpty(
+						Mono.defer(() -> other.route(request).map(RouterFunctions::cast)));
 	}
 
 	/**

spring-webflux/src/test/java/org/springframework/web/reactive/function/server/NestedRouteIntegrationTests.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2002-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.reactive.function.server;
+
+import org.junit.Before;
+import org.junit.Ignore;
+import org.junit.Test;
+import reactor.core.publisher.Mono;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.client.RestTemplate;
+
+import static org.junit.Assert.assertEquals;
+import static org.springframework.web.reactive.function.BodyInserters.fromObject;
+import static org.springframework.web.reactive.function.server.RequestPredicates.GET;
+import static org.springframework.web.reactive.function.server.RequestPredicates.pathPrefix;
+import static org.springframework.web.reactive.function.server.RouterFunctions.nest;
+import static org.springframework.web.reactive.function.server.RouterFunctions.route;
+
+/**
+ * @author Arjen Poutsma
+ */
+public class NestedRouteIntegrationTests
+		extends AbstractRouterFunctionIntegrationTests {
+
+	private RestTemplate restTemplate;
+
+	@Before
+	public void createRestTemplate() {
+		this.restTemplate = new RestTemplate();
+	}
+
+	@Override
+	protected RouterFunction<?> routerFunction() {
+		NestedHandler nestedHandler = new NestedHandler();
+		return nest(pathPrefix("/foo"),
+				route(GET("/bar"), nestedHandler::bar)
+				.andRoute(GET("/baz"), nestedHandler::baz));
+	}
+
+
+	@Test
+	public void bar() throws Exception {
+		ResponseEntity<String> result =
+				restTemplate.getForEntity("http://localhost:" + port + "/foo/bar", String.class);
+
+		assertEquals(HttpStatus.OK, result.getStatusCode());
+		assertEquals("bar", result.getBody());
+	}
+
+	@Test
+	@Ignore
+	public void baz() throws Exception {
+		ResponseEntity<String> result =
+				restTemplate.getForEntity("http://localhost:" + port + "/foo/baz", String.class);
+
+		assertEquals(HttpStatus.OK, result.getStatusCode());
+		assertEquals("baz", result.getBody());
+	}
+
+	private static class NestedHandler {
+
+		public Mono<ServerResponse> bar(ServerRequest request) {
+			return ServerResponse.ok().body(fromObject("bar"));
+		}
+
+		public Mono<ServerResponse> baz(ServerRequest request) {
+			return ServerResponse.ok().body(fromObject("baz"));
+		}
+
+	}
+
+}