Enhance constructor binding for List/Map/Array

Support List/Map/Array of simple values, or values supported
by type conversion.

Closes gh-34305

spring-context/src/main/java/org/springframework/validation/DataBinder.java

@@ -964,7 +964,7 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 						value = createMap(paramPath, paramType, resolvableType, valueResolver);
 					}
 					else if (paramType.isArray()) {
-						value = createArray(paramPath, resolvableType, valueResolver);
+						value = createArray(paramPath, paramType, resolvableType, valueResolver);
 					}
 				}
 
@@ -981,11 +981,9 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 						}
 					}
 					catch (TypeMismatchException ex) {
-						ex.initPropertyName(paramPath);
 						args[i] = null;
 						failedParamNames.add(paramPath);
-						getBindingResult().recordFieldValue(paramPath, paramType, value);
-						getBindingErrorProcessor().processPropertyAccessException(ex, getBindingResult());
+						handleTypeMismatchException(ex, paramPath, paramType, value);
 					}
 				}
 			}
@@ -1048,9 +1046,8 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 		return false;
 	}
 
-	@SuppressWarnings("unchecked")
 	@Nullable
-	private <V> List<V> createList(
+	private List<?> createList(
 			String paramPath, Class<?> paramType, ResolvableType type, ValueResolver valueResolver) {
 
 		ResolvableType elementType = type.getNested(2);
@@ -1058,18 +1055,21 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 		if (indexes == null) {
 			return null;
 		}
+
 		int size = (indexes.last() < this.autoGrowCollectionLimit ? indexes.last() + 1 : 0);
-		List<V> list = (List<V>) CollectionFactory.createCollection(paramType, size);
+		List<?> list = (List<?>) CollectionFactory.createCollection(paramType, size);
 		for (int i = 0; i < size; i++) {
 			list.add(null);
 		}
+
 		for (int index : indexes) {
-			list.set(index, (V) createObject(elementType, paramPath + "[" + index + "].", valueResolver));
+			String indexedPath = paramPath + "[" + index + "]";
+			list.set(index, createIndexedValue(paramPath, paramType, elementType, indexedPath, valueResolver));
 		}
+
 		return list;
 	}
 
-	@SuppressWarnings("unchecked")
 	@Nullable
 	private <V> Map<String, V> createMap(
 			String paramPath, Class<?> paramType, ResolvableType type, ValueResolver valueResolver) {
@@ -1080,34 +1080,42 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 			if (!name.startsWith(paramPath + "[")) {
 				continue;
 			}
+
 			int startIdx = paramPath.length() + 1;
 			int endIdx = name.indexOf(']', startIdx);
-			String nestedPath = name.substring(0, endIdx + 2);
 			boolean quoted = (endIdx - startIdx > 2 && name.charAt(startIdx) == '\'' && name.charAt(endIdx - 1) == '\'');
 			String key = (quoted ? name.substring(startIdx + 1, endIdx - 1) : name.substring(startIdx, endIdx));
+
 			if (map == null) {
 				map = CollectionFactory.createMap(paramType, 16);
 			}
-			if (!map.containsKey(key)) {
-				map.put(key, (V) createObject(elementType, nestedPath, valueResolver));
-			}
+
+			String indexedPath = name.substring(0, endIdx + 1);
+			map.put(key, createIndexedValue(paramPath, paramType, elementType, indexedPath, valueResolver));
 		}
+
 		return map;
 	}
 
 	@SuppressWarnings("unchecked")
 	@Nullable
-	private <V> V[] createArray(String paramPath, ResolvableType type, ValueResolver valueResolver) {
+	private <V> V[] createArray(
+			String paramPath, Class<?> paramType, ResolvableType type, ValueResolver valueResolver) {
+
 		ResolvableType elementType = type.getNested(2);
 		SortedSet<Integer> indexes = getIndexes(paramPath, valueResolver);
 		if (indexes == null) {
 			return null;
 		}
+
 		int size = (indexes.last() < this.autoGrowCollectionLimit ? indexes.last() + 1: 0);
 		V[] array = (V[]) Array.newInstance(elementType.resolve(), size);
+
 		for (int index : indexes) {
-			array[index] = (V) createObject(elementType, paramPath + "[" + index + "].", valueResolver);
+			String indexedPath = paramPath + "[" + index + "]";
+			array[index] = createIndexedValue(paramPath, paramType, elementType, indexedPath, valueResolver);
 		}
+
 		return array;
 	}
 
@@ -1118,14 +1126,46 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 			if (name.startsWith(paramPath + "[")) {
 				int endIndex = name.indexOf(']', paramPath.length() + 2);
 				String rawIndex = name.substring(paramPath.length() + 1, endIndex);
-				int index = Integer.parseInt(rawIndex);
-				indexes = (indexes != null ? indexes : new TreeSet<>());
-				indexes.add(index);
+				if (StringUtils.hasLength(rawIndex)) {
+					int index = Integer.parseInt(rawIndex);
+					indexes = (indexes != null ? indexes : new TreeSet<>());
+					indexes.add(index);
+				}
 			}
 		}
 		return indexes;
 	}
 
+	@SuppressWarnings("unchecked")
+	private <V> @Nullable V createIndexedValue(
+			String paramPath, Class<?> paramType, ResolvableType elementType,
+			String indexedPath, ValueResolver valueResolver) {
+
+		Object value = null;
+		Class<?> elementClass = elementType.resolve(Object.class);
+		Object rawValue = valueResolver.resolveValue(indexedPath, elementClass);
+		if (rawValue != null) {
+			try {
+				value = convertIfNecessary(rawValue, elementClass);
+			}
+			catch (TypeMismatchException ex) {
+				handleTypeMismatchException(ex, paramPath, paramType, rawValue);
+			}
+		}
+		else {
+			value = createObject(elementType, indexedPath + ".", valueResolver);
+		}
+		return (V) value;
+	}
+
+	private void handleTypeMismatchException(
+			TypeMismatchException ex, String paramPath, Class<?> paramType, @Nullable Object value) {
+
+		ex.initPropertyName(paramPath);
+		getBindingResult().recordFieldValue(paramPath, paramType, value);
+		getBindingErrorProcessor().processPropertyAccessException(ex, getBindingResult());
+	}
+
 	private void validateConstructorArgument(
 			Class<?> constructorClass, String nestedPath, String name, @Nullable Object value) {
 

spring-context/src/test/java/org/springframework/validation/DataBinderConstructTests.java

@@ -103,17 +103,17 @@ class DataBinderConstructTests {
 	}
 
 	@Test
-	void listBinding() {
+	void dataClassWithListBinding() {
 		MapValueResolver valueResolver = new MapValueResolver(Map.of(
 				"dataClassList[0].param1", "value1", "dataClassList[0].param2", "true",
 				"dataClassList[1].param1", "value2", "dataClassList[1].param2", "true",
 				"dataClassList[2].param1", "value3", "dataClassList[2].param2", "true"));
 
-		DataBinder binder = initDataBinder(ListDataClass.class);
+		DataBinder binder = initDataBinder(DataClassListRecord.class);
 		binder.construct(valueResolver);
 
-		ListDataClass dataClass = getTarget(binder);
-		List<DataClass> list = dataClass.dataClassList();
+		DataClassListRecord target = getTarget(binder);
+		List<DataClass> list = target.dataClassList();
 
 		assertThat(list).hasSize(3);
 		assertThat(list.get(0).param1()).isEqualTo("value1");
@@ -122,17 +122,17 @@ class DataBinderConstructTests {
 	}
 
 	@Test // gh-34145
-	void listBindingWithNonconsecutiveIndices() {
+	void dataClassWithListBindingWithNonconsecutiveIndices() {
 		MapValueResolver valueResolver = new MapValueResolver(Map.of(
 				"dataClassList[0].param1", "value1", "dataClassList[0].param2", "true",
 				"dataClassList[1].param1", "value2", "dataClassList[1].param2", "true",
 				"dataClassList[3].param1", "value3", "dataClassList[3].param2", "true"));
 
-		DataBinder binder = initDataBinder(ListDataClass.class);
+		DataBinder binder = initDataBinder(DataClassListRecord.class);
 		binder.construct(valueResolver);
 
-		ListDataClass dataClass = getTarget(binder);
-		List<DataClass> list = dataClass.dataClassList();
+		DataClassListRecord target = getTarget(binder);
+		List<DataClass> list = target.dataClassList();
 
 		assertThat(list.get(0).param1()).isEqualTo("value1");
 		assertThat(list.get(1).param1()).isEqualTo("value2");
@@ -140,17 +140,17 @@ class DataBinderConstructTests {
 	}
 
 	@Test
-	void mapBinding() {
+	void dataClassWithMapBinding() {
 		MapValueResolver valueResolver = new MapValueResolver(Map.of(
 				"dataClassMap[a].param1", "value1", "dataClassMap[a].param2", "true",
 				"dataClassMap[b].param1", "value2", "dataClassMap[b].param2", "true",
 				"dataClassMap['c'].param1", "value3", "dataClassMap['c'].param2", "true"));
 
-		DataBinder binder = initDataBinder(MapDataClass.class);
+		DataBinder binder = initDataBinder(DataClassMapRecord.class);
 		binder.construct(valueResolver);
 
-		MapDataClass dataClass = getTarget(binder);
-		Map<String, DataClass> map = dataClass.dataClassMap();
+		DataClassMapRecord target = getTarget(binder);
+		Map<String, DataClass> map = target.dataClassMap();
 
 		assertThat(map).hasSize(3);
 		assertThat(map.get("a").param1()).isEqualTo("value1");
@@ -159,17 +159,17 @@ class DataBinderConstructTests {
 	}
 
 	@Test
-	void arrayBinding() {
+	void dataClassWithArrayBinding() {
 		MapValueResolver valueResolver = new MapValueResolver(Map.of(
 				"dataClassArray[0].param1", "value1", "dataClassArray[0].param2", "true",
 				"dataClassArray[1].param1", "value2", "dataClassArray[1].param2", "true",
 				"dataClassArray[2].param1", "value3", "dataClassArray[2].param2", "true"));
 
-		DataBinder binder = initDataBinder(ArrayDataClass.class);
+		DataBinder binder = initDataBinder(DataClassArrayRecord.class);
 		binder.construct(valueResolver);
 
-		ArrayDataClass dataClass = getTarget(binder);
-		DataClass[] array = dataClass.dataClassArray();
+		DataClassArrayRecord target = getTarget(binder);
+		DataClass[] array = target.dataClassArray();
 
 		assertThat(array).hasSize(3);
 		assertThat(array[0].param1()).isEqualTo("value1");
@@ -177,6 +177,40 @@ class DataBinderConstructTests {
 		assertThat(array[2].param1()).isEqualTo("value3");
 	}
 
+	@Test
+	void simpleListBinding() {
+		MapValueResolver valueResolver = new MapValueResolver(Map.of("integerList[0]", "1", "integerList[1]", "2"));
+
+		DataBinder binder = initDataBinder(IntegerListRecord.class);
+		binder.construct(valueResolver);
+
+		IntegerListRecord target = getTarget(binder);
+		assertThat(target.integerList()).containsExactly(1, 2);
+	}
+
+	@Test
+	void simpleMapBinding() {
+		MapValueResolver valueResolver = new MapValueResolver(Map.of("integerMap[a]", "1", "integerMap[b]", "2"));
+
+		DataBinder binder = initDataBinder(IntegerMapRecord.class);
+		binder.construct(valueResolver);
+
+		IntegerMapRecord target = getTarget(binder);
+		assertThat(target.integerMap()).hasSize(2).containsEntry("a", 1).containsEntry("b", 2);
+	}
+
+	@Test
+	void simpleArrayBinding() {
+		MapValueResolver valueResolver = new MapValueResolver(Map.of("integerArray[0]", "1", "integerArray[1]", "2"));
+
+		DataBinder binder = initDataBinder(IntegerArrayRecord.class);
+		binder.construct(valueResolver);
+
+		IntegerArrayRecord target = getTarget(binder);
+		assertThat(target.integerArray()).containsExactly(1, 2);
+	}
+
+
 	@SuppressWarnings("SameParameterValue")
 	private static DataBinder initDataBinder(Class<?> targetType) {
 		DataBinder binder = new DataBinder(null);
@@ -248,15 +282,27 @@ class DataBinderConstructTests {
 	}
 
 
-	private record ListDataClass(List<DataClass> dataClassList) {
+	private record DataClassListRecord(List<DataClass> dataClassList) {
+	}
+
+
+	private record DataClassMapRecord(Map<String, DataClass> dataClassMap) {
+	}
+
+
+	private record DataClassArrayRecord(DataClass[] dataClassArray) {
+	}
+
+
+	private record IntegerListRecord(List<Integer> integerList) {
 	}
 
 
-	private record MapDataClass(Map<String, DataClass> dataClassMap) {
+	private record IntegerMapRecord(Map<String, Integer> integerMap) {
 	}
 
 
-	private record ArrayDataClass(DataClass[] dataClassArray) {
+	private record IntegerArrayRecord(Integer[] integerArray) {
 	}