GH-602 Ensure collections with converted items are not converted again

Resolves #602

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistry.java

@@ -61,6 +61,7 @@ import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.converter.CompositeMessageConverter;
 import org.springframework.messaging.support.MessageBuilder;
 import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
@@ -356,7 +357,7 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 		 * @return the type of the item if wrapped otherwise the provided type.
 		 */
 		public Type getItemType(Type type) {
-			if (FunctionTypeUtils.isPublisher(type) || FunctionTypeUtils.isMessage(type)) {
+			if (FunctionTypeUtils.isPublisher(type) || FunctionTypeUtils.isMessage(type) || FunctionTypeUtils.isTypeCollection(type)) {
 				type = FunctionTypeUtils.getGenericType(type);
 			}
 			return type;
@@ -784,19 +785,6 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 						? input
 						: new OriginalMessageHolder(((Message) input).getPayload(), (Message<?>) input);
 			}
-//			else if (FunctionTypeUtils.isMultipleArgumentType(type)) {
-//				Type[] inputTypes = ((ParameterizedType) type).getActualTypeArguments();
-//				Object[] multipleValueArguments = this.parseMultipleValueArguments(input, inputTypes.length);
-//				Object[] convertedInputs = new Object[inputTypes.length];
-//				for (int i = 0; i < multipleValueArguments.length; i++) {
-//					Object cInput = this.convertInputIfNecessary(multipleValueArguments[i], inputTypes[i]);
-//					convertedInputs[i] = cInput;
-//				}
-//				convertedInput = Tuples.fromArray(convertedInputs);
-//			}
-//			else if (input instanceof Publisher) {
-//				convertedInput = this.convertInputPublisherIfNecessary((Publisher) input, type);
-//			}
 			else if (input instanceof Message) {
 				convertedInput = this.convertInputMessageIfNecessary((Message) input, type);
 				if (convertedInput == null) { // give ConversionService a chance
@@ -949,6 +937,14 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 			if (message.getPayload() instanceof Optional) {
 				return message;
 			}
+			if (message.getPayload() instanceof Collection<?>) {
+				Type itemType = FunctionTypeUtils.getImmediateGenericType(type, 0);
+				Type collectionType = CollectionUtils.findCommonElementType((Collection<?>) message.getPayload());
+				if (collectionType == itemType) {
+					return message.getPayload();
+				}
+			}
+			//if (message.getPayload().getClass().isAss) {
 
 			Object convertedInput = message;
 			type = this.extractActualValueTypeIfNecessary(type);
@@ -973,7 +969,6 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 					convertedInput = MessageBuilder.withPayload(convertedInput).copyHeaders(message.getHeaders()).build();
 				}
 			}
-//			convertedInput = convertedInput == null ? message.getPayload() : convertedInput;
 			return convertedInput;
 		}
 

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/JsonMessageConverter.java

@@ -18,6 +18,7 @@ package org.springframework.cloud.function.context.config;
 
 import java.lang.reflect.Type;
 import java.nio.charset.StandardCharsets;
+import java.util.Collection;
 
 import org.springframework.cloud.function.json.JsonMapper;
 import org.springframework.lang.Nullable;
@@ -73,12 +74,9 @@ public class JsonMessageConverter extends AbstractMessageConverter {
 
 	@Override
 	protected Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
-		if (targetClass.isInstance(message.getPayload())) {
+		if (targetClass.isInstance(message.getPayload()) && !(message.getPayload() instanceof Collection<?>)) {
 			return message.getPayload();
 		}
-
-
-
 		Type convertToType = conversionHint == null ? targetClass : (Type) conversionHint;
 		try {
 			return this.jsonMapper.fromJson(message.getPayload(), convertToType);

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/json/GsonMapper.java

@@ -46,7 +46,7 @@ public class GsonMapper extends JsonMapper {
 	}
 
 	@Override
-	public <T> T fromJson(Object json, Type type) {
+	protected <T> T doFromJson(Object json, Type type) {
 		T convertedValue = null;
 		if (json instanceof byte[]) {
 			convertedValue = this.gson.fromJson(new String(((byte[]) json), StandardCharsets.UTF_8), type);

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/json/JacksonMapper.java

@@ -42,7 +42,7 @@ public class JacksonMapper extends JsonMapper {
 	}
 
 	@Override
-	public <T> T fromJson(Object json, Type type) {
+	protected <T> T doFromJson(Object json, Type type) {
 		T convertedValue = null;
 		JavaType constructType = TypeFactory.defaultInstance().constructType(type);
 

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/json/JsonMapper.java

@@ -19,11 +19,14 @@ package org.springframework.cloud.function.json;
 import java.lang.reflect.Type;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
 import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.cloud.function.context.catalog.FunctionTypeUtils;
 import org.springframework.core.ResolvableType;
 
 /**
@@ -60,7 +63,25 @@ public abstract class JsonMapper {
 	@Deprecated
 	abstract <T> T toObject(String json, Type type);
 
-	public abstract <T> T fromJson(Object json, Type type);
+	@SuppressWarnings("unchecked")
+	public <T> T fromJson(Object json, Type type) {
+		if (json instanceof Collection<?>) {
+			Collection<?> inputs = (Collection<?>) json;
+			Type itemType = FunctionTypeUtils.getImmediateGenericType(type, 0);
+			Collection<?> results = FunctionTypeUtils.getRawType(type).isAssignableFrom(List.class)
+					? new ArrayList<>()
+					: new HashSet<>();
+			for (Object input : inputs) {
+				results.add(this.doFromJson(input, itemType));
+			}
+			return (T) results;
+		}
+		else {
+			return this.doFromJson(json, type);
+		}
+	}
+
+	protected abstract <T> T doFromJson(Object json, Type type);
 
 	public byte[] toJson(Object value) {
 		byte[] result = null;

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/userissues/UserIssuesTests.java

@@ -0,0 +1,122 @@
+/*
+ * Copyright 2020-2020 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.function.userissues;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Function;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.cloud.function.context.FunctionCatalog;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.support.GenericMessage;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ *
+ * @author Oleg Zhurakousky
+ *
+ */
+public class UserIssuesTests {
+
+	private FunctionCatalog configureCatalog(Class<?>... configClass) {
+		ApplicationContext context = new SpringApplicationBuilder(configClass).run(
+				"--logging.level.org.springframework.cloud.function=DEBUG", "--spring.main.lazy-initialization=true");
+		FunctionCatalog catalog = context.getBean(FunctionCatalog.class);
+		return catalog;
+	}
+
+	@BeforeEach
+	public void before() {
+		System.clearProperty("spring.cloud.function.definition");
+	}
+
+	@Test
+	public void testIssue602() throws Exception {
+		FunctionCatalog catalog = this.configureCatalog(Issue602Configuration.class);
+		Function<Message<String>, Integer> function = catalog.lookup("consumer");
+		int result = function.apply(
+				new GenericMessage<String>("[{\"name\":\"julien\"},{\"name\":\"ricky\"},{\"name\":\"bubbles\"}]"));
+		assertThat(result).isEqualTo(3);
+	}
+
+	@Test
+	public void testIssue602asPOJO() throws Exception {
+		FunctionCatalog catalog = this.configureCatalog(Issue602Configuration.class);
+		Function<Message<List<Product>>, Integer> function = catalog.lookup("consumer");
+		ArrayList<Product> products = new ArrayList<>();
+		Product p = new Product();
+		p.setName("julien");
+		products.add(p);
+		p = new Product();
+		p.setName("ricky");
+		products.add(p);
+		p = new Product();
+		p.setName("bubbles");
+		products.add(p);
+		int result = function.apply(new GenericMessage<List<Product>>(products));
+		assertThat(result).isEqualTo(3);
+
+	}
+
+	@Test
+	public void testIssue602asCollectionOfUnconvertedItems() throws Exception {
+		FunctionCatalog catalog = this.configureCatalog(Issue602Configuration.class);
+		Function<Message<List<String>>, Integer> function = catalog.lookup("consumer");
+		ArrayList<String> products = new ArrayList<>();
+		products.add("{\"name\":\"julien\"}");
+		products.add("{\"name\":\"ricky\"}");
+		products.add("{\"name\":\"bubbles\"}");
+		int result = function.apply(new GenericMessage<List<String>>(products));
+		assertThat(result).isEqualTo(3);
+
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	public static class Issue602Configuration {
+		@Bean
+		public Function<List<Product>, Integer> consumer() {
+			return v -> {
+				assertThat(v.get(0).getName()).isEqualTo("julien");
+				assertThat(v.get(1).getName()).isEqualTo("ricky");
+				assertThat(v.get(2).getName()).isEqualTo("bubbles");
+				return v.size();
+			};
+		}
+	}
+
+	public static class Product {
+		private String name;
+
+		public String getName() {
+			return name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+	}
+}