GH-596 Add support for handling conversion of complex types

Resolves #596

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

@@ -676,11 +676,7 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 				}
 			}
 			else {
-				Class<?> inputType = this.isTypePublisher(type) || this.isInputTypeMessage()
-						? TypeResolver.resolveRawClass(FunctionTypeUtils.getImmediateGenericType(type, 0), null)
-						: this.getRawClassFor(type);
-
-				convertedInput = this.convertNonMessageInputIfNecessary(inputType, input);
+				convertedInput = this.convertNonMessageInputIfNecessary(type, input);
 			}
 			// wrap in Message if necessary
 			if (this.isWrapConvertedInputInMessage(convertedInput)) {
@@ -721,18 +717,25 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 		/*
 		 *
 		 */
-		private Object convertNonMessageInputIfNecessary(Class<?> inputType, Object input) {
+		private Object convertNonMessageInputIfNecessary(Type inputType, Object input) {
 			Object convertedInput = input;
-			if (!inputType.isAssignableFrom(input.getClass())) {
-				if (inputType != input.getClass()
-						&& SimpleFunctionRegistry.this.conversionService != null
-						&& SimpleFunctionRegistry.this.conversionService.canConvert(input.getClass(), inputType)) {
-					convertedInput = SimpleFunctionRegistry.this.conversionService.convert(input, inputType);
+			Class<?> rawInputType = this.isTypePublisher(inputType) || this.isInputTypeMessage()
+					? TypeResolver.resolveRawClass(FunctionTypeUtils.getImmediateGenericType(inputType, 0), null)
+					: this.getRawClassFor(inputType);
+
+			if (JsonMapper.isJsonString(input) && !Message.class.isAssignableFrom(rawInputType)) {
+				if (FunctionTypeUtils.isMessage(inputType)) {
+					inputType = FunctionTypeUtils.getGenericType(inputType);
 				}
-				else {
+				if (Object.class != inputType) {
 					convertedInput = SimpleFunctionRegistry.this.jsonMapper.fromJson(input, inputType);
 				}
 			}
+			else if (SimpleFunctionRegistry.this.conversionService != null
+					&& !rawInputType.equals(input.getClass())
+					&& SimpleFunctionRegistry.this.conversionService.canConvert(input.getClass(), rawInputType)) {
+				convertedInput = SimpleFunctionRegistry.this.conversionService.convert(input, rawInputType);
+			}
 			return convertedInput;
 		}
 
@@ -764,6 +767,10 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 			return type;
 		}
 
+		private boolean isConversionHintRequired(Object actualType, Class<?> rawType) {
+			return rawType != actualType;
+		}
+
 		/*
 		 *
 		 */
@@ -778,7 +785,7 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 			Object convertedInput = message;
 			type = this.extractActualValueTypeIfNecessary(type);
 			Class rawType = TypeResolver.resolveRawClass(type, null);
-			convertedInput = FunctionTypeUtils.isTypeCollection(type)
+			convertedInput = this.isConversionHintRequired(type, rawType)
 					? SimpleFunctionRegistry.this.messageConverter.fromMessage(message, rawType, type)
 					: SimpleFunctionRegistry.this.messageConverter.fromMessage(message, rawType);
 

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

@@ -98,12 +98,16 @@ public abstract class JsonMapper {
 	 */
 	public static boolean isJsonString(Object value) {
 		boolean isJson = false;
+		if (value instanceof byte[]) {
+			value = new String((byte[]) value, StandardCharsets.UTF_8);
+		}
 		if (value instanceof String) {
 			String str = ((String) value).trim();
 			isJson = (str.startsWith("\"") && str.endsWith("\"")) ||
 					(str.startsWith("{") && str.endsWith("}")) ||
 					(str.startsWith("[") && str.endsWith("]"));
 		}
+
 		return isJson;
 	}
 }

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistryTests.java

@@ -269,6 +269,29 @@ public class BeanFactoryAwareFunctionRegistryTests {
 		assertThat(block).isNull();
 	}
 
+	@SuppressWarnings({ "rawtypes", "unchecked" })
+	@Test
+	public void textTypeConversionWithComplexInputType() {
+		FunctionCatalog catalog = this.configureCatalog(ComplexTypeFunctionConfiguration.class);
+		Function function = catalog.lookup("function");
+
+		// as String
+		String result = (String) function.apply("{\"key\":\"purchase\",\"data\":{\"name\":\"bike\"}}");
+		assertThat(result).isEqualTo("BIKE");
+
+		// as byte[]
+		result = (String) function.apply("{\"key\":\"purchase\",\"data\":{\"name\":\"bike\"}}".getBytes());
+		assertThat(result).isEqualTo("BIKE");
+
+		// as Message<String>
+		result = (String) function.apply(MessageBuilder.withPayload("{\"key\":\"purchase\",\"data\":{\"name\":\"bike\"}}").build());
+		assertThat(result).isEqualTo("BIKE");
+
+		// as Message<BYTE[]>
+		result = (String) function.apply(MessageBuilder.withPayload("{\"key\":\"purchase\",\"data\":{\"name\":\"bike\"}}".getBytes()).build());
+		assertThat(result).isEqualTo("BIKE");
+	}
+
 	// MULTI INPUT/OUTPUT
 
 
@@ -919,4 +942,48 @@ public class BeanFactoryAwareFunctionRegistryTests {
 		}
 
 	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	public static class ComplexTypeFunctionConfiguration {
+		@Bean
+		public Function<Event<String, Product>, String> function() {
+			return v -> v.getData().getName().toUpperCase();
+		}
+	}
+
+	private static class Product {
+		private String name;
+
+		public String getName() {
+			return name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+	}
+
+	private static class Event<K, V> {
+
+		private K key;
+
+		public K getKey() {
+			return key;
+		}
+
+		public void setKey(K key) {
+			this.key = key;
+		}
+
+		private V data;
+
+		public V getData() {
+			return data;
+		}
+
+		public void setData(V data) {
+			this.data = data;
+		}
+	}
 }

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistryTests.java

@@ -127,6 +127,8 @@ public class SimpleFunctionRegistryTests {
 		assertThat(lookedUpFunction).isNull();
 	}
 
+
+
 	@Test
 	public void testFunctionComposition() {
 		FunctionRegistration<UpperCase> upperCaseRegistration = new FunctionRegistration<>(
@@ -500,5 +502,4 @@ public class SimpleFunctionRegistryTests {
 				.map(lst -> lst.stream().map(Person::getName).collect(Collectors.toList()));
 		}
 	}
-
 }