Initial functionality for default function routing

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/config/DefaultFunctionConfiguration.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2013-2025 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
+ *
+ *      https://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.cloud.gateway.server.mvc.config;
+
+import static org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions.route;
+import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.fn;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.function.RouterFunction;
+import org.springframework.web.servlet.function.ServerResponse;
+
+@Configuration
+@ConditionalOnClass(name = "org.springframework.cloud.function.context.FunctionCatalog")
+@ConditionalOnProperty(name = "spring.cloud.gateway.function.enabled", havingValue = "true", matchIfMissing = true)
+public class DefaultFunctionConfiguration {
+
+	@Bean
+	RouterFunction<ServerResponse> gatewayToFunctionRouter() {
+		// @formatter:off
+		return route("functionroute")
+				.POST("/{path}/{name}", fn("{path}/{name}"))
+				.POST("/{path}", fn("{path}"))
+				.GET("/{path}/{name}", fn("{path}/{name}"))
+				.GET("/{path}", fn("{path}"))
+			.build();
+		// @formatter:on
+	}
+
+}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/handler/HandlerFunctions.java

@@ -26,8 +26,11 @@
 
 import jakarta.servlet.ServletException;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.cloud.function.context.FunctionCatalog;
 import org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry.FunctionInvocationWrapper;
+import org.springframework.cloud.gateway.server.mvc.GatewayMvcClassPathWarningAutoConfiguration;
 import org.springframework.cloud.gateway.server.mvc.common.MvcUtils;
 import org.springframework.cloud.gateway.server.mvc.config.RouteProperties;
 import org.springframework.cloud.stream.function.StreamOperations;
@@ -43,6 +46,8 @@
 
 public abstract class HandlerFunctions {
 
+	private static final Log log = LogFactory.getLog(GatewayMvcClassPathWarningAutoConfiguration.class);
+
 	private HandlerFunctions() {
 
 	}
@@ -56,12 +61,29 @@ public static HandlerFunction<ServerResponse> fn(RouteProperties routeProperties
 	public static HandlerFunction<ServerResponse> fn(String functionName) {
 		Assert.hasText(functionName, "'functionName' must not be empty");
 		return request -> {
-			String expandedFunctionName = MvcUtils.expand(request, functionName);
 			FunctionCatalog functionCatalog = MvcUtils.getApplicationContext(request).getBean(FunctionCatalog.class);
-			FunctionInvocationWrapper function = functionCatalog.lookup(expandedFunctionName,
-					request.headers().accept().stream().map(MimeType::toString).toArray(String[]::new));
+			String expandedFunctionName = MvcUtils.expand(request, functionName);
+			FunctionInvocationWrapper function;
+			Object body = null;
+			if (expandedFunctionName.contains("/")) {
+				String[] functionBodySplit = expandedFunctionName.split("/");
+				function = functionCatalog.lookup(functionBodySplit[0],
+						request.headers().accept().stream().map(MimeType::toString).toArray(String[]::new));
+				if (function != null && function.isSupplier()) {
+					log.warn("Supplier must not have any arguments. Supplier: '" + function.getFunctionDefinition()
+							+ "' has '" + functionBodySplit[1] + "' as an argument which is ignored.");
+				}
+				body = functionBodySplit[1];
+			}
+			else {
+				function = functionCatalog.lookup(expandedFunctionName,
+						request.headers().accept().stream().map(MimeType::toString).toArray(String[]::new));
+			}
+
 			if (function != null) {
-				Object body = function.isSupplier() ? null : request.body(function.getRawInputType());
+				if (body == null) {
+					body = function.isSupplier() ? null : request.body(function.getRawInputType());
+				}
 				return processRequest(request, function, body, false, Collections.emptyList(), Collections.emptyList());
 			}
 			return ServerResponse.notFound().build();

spring-cloud-gateway-server-mvc/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -1,4 +1,5 @@
 org.springframework.cloud.gateway.server.mvc.GatewayServerMvcAutoConfiguration
 org.springframework.cloud.gateway.server.mvc.GatewayMvcClassPathWarningAutoConfiguration
 org.springframework.cloud.gateway.server.mvc.handler.GatewayMultipartAutoConfiguration
-org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration
+org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration
+org.springframework.cloud.gateway.server.mvc.config.DefaultFunctionConfiguration

spring-cloud-gateway-server-mvc/src/test/java/org/springframework/cloud/gateway/server/mvc/handler/DefaultRouteFunctionHandlerTests.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2013-2025 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
+ *
+ *      https://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.cloud.gateway.server.mvc.handler;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Locale;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.gateway.server.mvc.test.client.TestRestClient;
+import org.springframework.context.annotation.Bean;
+import org.springframework.http.MediaType;
+
+@SpringBootTest(properties = {}, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class DefaultRouteFunctionHandlerTests {
+
+	@Autowired
+	private TestRestClient restClient;
+
+	@Test
+	public void testSupplierWorks() {
+		restClient.get()
+			.uri("/hello")
+			.accept(MediaType.TEXT_PLAIN)
+			.exchange()
+			.expectStatus()
+			.isOk()
+			.expectBody(String.class)
+			.isEqualTo("hello");
+	}
+
+	@Test
+	public void testFunctionWorksGET() {
+		restClient.get()
+			.uri("/upper/bob")
+			.accept(MediaType.TEXT_PLAIN)
+			.exchange()
+			.expectStatus()
+			.isOk()
+			.expectBody(String.class)
+			.isEqualTo("BOB");
+	}
+
+	@Test
+	public void testFunctionWorksPOST() {
+		restClient.post()
+			.uri("/upper")
+			.accept(MediaType.APPLICATION_JSON)
+			.bodyValue("bob")
+			.exchange()
+			.expectStatus()
+			.isOk()
+			.expectBody(String.class)
+			.isEqualTo("BOB");
+	}
+
+	@Test
+	public void testConsumerWorksGET() {
+		restClient.get().uri("/consume/hello").accept(MediaType.TEXT_PLAIN).exchange().expectStatus().isAccepted();
+		assertThat(TestConfiguration.consumerInvoked).isTrue();
+	}
+
+	@Test
+	public void testConsumerWorksPOST() {
+		restClient.post()
+			.uri("/consume")
+			.accept(MediaType.APPLICATION_JSON)
+			.bodyValue("hello")
+			.exchange()
+			.expectStatus()
+			.isAccepted();
+		assertThat(TestConfiguration.consumerInvoked).isTrue();
+	}
+
+	@SpringBootConfiguration
+	@EnableAutoConfiguration
+	protected static class TestConfiguration {
+
+		static boolean consumerInvoked;
+
+		@Bean
+		Function<String, String> upper() {
+			return s -> s.toUpperCase(Locale.ROOT);
+		}
+
+		@Bean
+		Consumer<String> consume() {
+			return s -> {
+				consumerInvoked = false;
+				assertThat(s).isEqualTo("hello");
+				consumerInvoked = true;
+			};
+		}
+
+		@Bean
+		Supplier<String> hello() {
+			return () -> "hello";
+		}
+
+	}
+
+}