Ability to extend default function result handling

Fixes #757

spring-cloud-function-samples/function-sample-azure/src/main/java/example/Config.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -19,16 +19,20 @@ package example;
 import java.util.Map;
 import java.util.function.Function;
 
+import com.microsoft.azure.functions.ExecutionContext;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.cloud.function.json.JsonMapper;
 import org.springframework.context.annotation.Bean;
 import org.springframework.messaging.Message;
 
-import com.microsoft.azure.functions.ExecutionContext;
-
-import reactor.core.publisher.Mono;
-
+/**
+ * @author Oleg Zhurakousky
+ * @author Chris Bono
+ */
 @SpringBootApplication
 public class Config {
 
@@ -67,13 +71,14 @@ public class Config {
 		};
 	}
 
-
 	@Bean
 	public Function<Mono<String>, Mono<String>> uppercaseReactive() {
-		return mono -> mono.map(value -> {
-			return value.toUpperCase();
-		});
+		return mono -> mono.map(value -> value.toUpperCase());
 	}
 
+	@Bean
+	public Function<Flux<String>, Flux<String>> echoStream() {
+		return flux -> flux.map(value -> value.toUpperCase());
+	}
 }
 

spring-cloud-function-samples/function-sample-azure/src/main/java/example/ReactiveEchoCustomResultHandler.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2022-2022 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 example;
+
+import java.util.List;
+
+import com.microsoft.azure.functions.ExecutionContext;
+import com.microsoft.azure.functions.HttpMethod;
+import com.microsoft.azure.functions.HttpRequestMessage;
+import com.microsoft.azure.functions.annotation.AuthorizationLevel;
+import com.microsoft.azure.functions.annotation.FunctionName;
+import com.microsoft.azure.functions.annotation.HttpTrigger;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import reactor.core.publisher.Flux;
+
+import org.springframework.cloud.function.adapter.azure.FunctionInvoker;
+import org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry.FunctionInvocationWrapper;
+
+/**
+ * Sample that shows how to customize the default function result handling by operating on the {@link Flux} returned
+ * from the {@link Config#echoStream()} echoStream} function.
+ *
+ * @author Chris Bono
+ */
+public class ReactiveEchoCustomResultHandler extends FunctionInvoker<List<String>, String> {
+
+	private static final Log logger = LogFactory.getLog(ReactiveEchoCustomResultHandler.class);
+
+	@FunctionName("echoStream")
+	public String execute(@HttpTrigger(name = "req", methods = {HttpMethod.GET, HttpMethod.POST}, authLevel = AuthorizationLevel.ANONYMOUS)
+			HttpRequestMessage<List<String>> request, ExecutionContext context
+	) {
+		return handleRequest(request.getBody(), context);
+	}
+
+	@Override
+	protected String postProcessFluxFunctionResult(List<String> rawInputs, Object functionInputs, Flux<?> functionResult,
+		FunctionInvocationWrapper function, ExecutionContext executionContext
+	) {
+		functionResult
+			.doFirst(() -> executionContext.getLogger().info("BEGIN echo post-processing work ..."))
+			.mapNotNull((v) -> v.toString().toUpperCase())
+			.doFinally((signalType) -> executionContext.getLogger().info("END echo post-processing work"))
+			.subscribe((v) -> executionContext.getLogger().info("   " + v));
+		return "Kicked off job for " + rawInputs;
+	}
+
+}