GH-249, Add full HTTP support to SpringBootApiGatewayRequestHandler

* Add support for handling APIGatewayProxyRequestEvent objects with
empty body (should apply to all GET and DELETE requests, which
comply with recommandation of RFC-7231)

* Add support ReSTful APIs: path and query string parameters as well
as the HTTP method are now extracted from the
APIGatewayProxyRequestEvent object and forwarded to the function
as message headers

* Extend unit tests accordingly

spring-cloud-function-adapters/spring-cloud-function-adapter-aws/src/main/java/org/springframework/cloud/function/adapter/aws/SpringBootApiGatewayRequestHandler.java

@@ -18,6 +18,7 @@ package org.springframework.cloud.function.adapter.aws;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Optional;
 
 import com.amazonaws.services.lambda.runtime.Context;
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
@@ -36,6 +37,7 @@ import org.springframework.messaging.support.GenericMessage;
  * @author Dave Syer
  * @author Oleg Zhurakousky
  * @author Semyon Fishman
+ * @author Markus Gulden
  */
 public class SpringBootApiGatewayRequestHandler extends
 		SpringBootRequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
@@ -56,12 +58,22 @@ public class SpringBootApiGatewayRequestHandler extends
 
 	@Override
 	protected Object convertEvent(APIGatewayProxyRequestEvent event) {
-		Object body = deserializeBody(event.getBody());
-		if (functionAcceptsMessage()) {
-			return new GenericMessage<>(body, getHeaders(event));
+
+		if (event.getBody() != null) {
+			if (functionAcceptsMessage()) {
+				return new GenericMessage<>(deserializeBody(event.getBody()), getHeaders(event));
+			}
+			else {
+				return deserializeBody(event.getBody());
+			}
 		}
 		else {
-			return body;
+			if (functionAcceptsMessage()) {
+				return new GenericMessage<Optional<Void>>(Optional.empty(), getHeaders(event));
+			}
+			else {
+				return Optional.empty();
+			}
 		}
 	}
 
@@ -83,6 +95,13 @@ public class SpringBootApiGatewayRequestHandler extends
 		if (event.getHeaders() != null) {
 			headers.putAll(event.getHeaders());
 		}
+		if (event.getQueryStringParameters() != null) {
+			headers.putAll(event.getQueryStringParameters());
+		}
+		if (event.getPathParameters() != null) {
+			headers.putAll(event.getPathParameters());
+		}
+		headers.put("httpMethod", event.getHttpMethod());
 		headers.put("request", event);
 		return new MessageHeaders(headers);
 	}

spring-cloud-function-adapters/spring-cloud-function-adapter-aws/src/test/java/org/springframework/cloud/function/adapter/aws/SpringBootApiGatewayRequestHandlerTests.java

@@ -17,6 +17,7 @@
 package org.springframework.cloud.function.adapter.aws;
 
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Consumer;
 import java.util.function.Function;
@@ -37,7 +38,8 @@ import org.springframework.messaging.support.GenericMessage;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- *
+ * @author Dimitry Declercq
+ * @author Markus Gulden
  */
 public class SpringBootApiGatewayRequestHandlerTests {
 
@@ -102,6 +104,47 @@ public class SpringBootApiGatewayRequestHandlerTests {
 				.isEqualTo("{\"value\":\"FOO\"}");
 	}
 
+
+	@Test
+	public void functionMessageBeanWithRequestParameters() {
+		this.handler = new SpringBootApiGatewayRequestHandler(
+				FunctionMessageEchoReqParametersConfig.class);
+		APIGatewayProxyRequestEvent request = new APIGatewayProxyRequestEvent();
+		request.setPathParameters(Collections.singletonMap("path", "pathValue"));
+		request.setQueryStringParameters(Collections.singletonMap("query", "queryValue"));
+		request.setHeaders(Collections.singletonMap("test-header", "headerValue"));
+		request.setHttpMethod("GET");
+
+		Object output = this.handler.handleRequest(request, null);
+		assertThat(output).isInstanceOf(APIGatewayProxyResponseEvent.class);
+		assertThat(((APIGatewayProxyResponseEvent) output).getStatusCode())
+				.isEqualTo(200);
+		assertThat(((APIGatewayProxyResponseEvent) output).getHeaders().get("path"))
+				.isEqualTo("pathValue");
+		assertThat(((APIGatewayProxyResponseEvent) output).getHeaders().get("query"))
+				.isEqualTo("queryValue");
+		assertThat(
+				((APIGatewayProxyResponseEvent) output).getHeaders().get("test-header"))
+						.isEqualTo("headerValue");
+		assertThat(((APIGatewayProxyResponseEvent) output).getHeaders().get("httpMethod"))
+				.isEqualTo("GET");
+		assertThat(((APIGatewayProxyResponseEvent) output).getBody())
+				.isEqualTo("{\"value\":\"body\"}");
+	}
+
+	@Test
+	public void functionMessageBeanWithEmptyResponse() {
+		this.handler = new SpringBootApiGatewayRequestHandler(
+				FunctionMessageConsumerConfig.class);
+		APIGatewayProxyRequestEvent request = new APIGatewayProxyRequestEvent();
+
+		Object output = this.handler.handleRequest(request, null);
+		assertThat(output).isInstanceOf(APIGatewayProxyResponseEvent.class);
+		assertThat(((APIGatewayProxyResponseEvent) output).getStatusCode())
+				.isEqualTo(200);
+		assertThat(((APIGatewayProxyResponseEvent) output).getBody()).isNull();
+	}
+
 	@Configuration
 	@Import({ ContextFunctionCatalogAutoConfiguration.class,
 			JacksonAutoConfiguration.class })
@@ -140,6 +183,38 @@ public class SpringBootApiGatewayRequestHandlerTests {
 
 	}
 
+	@Configuration
+	@Import({ ContextFunctionCatalogAutoConfiguration.class,
+			JacksonAutoConfiguration.class })
+	protected static class FunctionMessageEchoReqParametersConfig {
+
+		@Bean
+		public Function<Message<Foo>, Message<Bar>> function() {
+			return (message -> {
+				Map<String, Object> headers = new HashMap<>();
+				headers.put("path", message.getHeaders().get("path"));
+				headers.put("query", message.getHeaders().get("query"));
+				headers.put("test-header", message.getHeaders().get("test-header"));
+				headers.put("httpMethod", message.getHeaders().get("httpMethod"));
+				return new GenericMessage<>(new Bar("body"), headers);
+			});
+		}
+
+	}
+
+	@Configuration
+	@Import({ ContextFunctionCatalogAutoConfiguration.class,
+			JacksonAutoConfiguration.class })
+	protected static class FunctionMessageConsumerConfig {
+
+		@Bean
+		public Consumer<Message<Foo>> function() {
+			return (foo -> {
+			});
+		}
+
+	}
+
 	protected static class Foo {
 
 		private String value;