Improve method validation for container elements

This change moves container element properties from ParameterErrors
to base class ParameterValidationResult, and makes that support
independent of whether violations are nested within a container
element bean or through constraints on container elements, e.g.
`List<@NotBlank String>`.

Closes gh-31887

spring-context/src/main/java/org/springframework/validation/beanvalidation/MethodValidationAdapter.java

@@ -301,8 +301,8 @@ public class MethodValidationAdapter implements MethodValidator {
 			Function<Integer, MethodParameter> parameterFunction,
 			Function<Integer, Object> argumentFunction) {
 
-		Map<MethodParameter, ParamResultBuilder> paramViolations = new LinkedHashMap<>();
+		Map<Path.Node, ParamValidationResultBuilder> paramViolations = new LinkedHashMap<>();
-		Map<Path.Node, BeanResultBuilder> beanViolations = new LinkedHashMap<>();
+		Map<Path.Node, ParamErrorsBuilder> nestedViolations = new LinkedHashMap<>();
 
 		for (ConstraintViolation<Object> violation : violations) {
 			Iterator<Path.Node> itr = violation.getPropertyPath().iterator();
@@ -322,59 +322,62 @@ public class MethodValidationAdapter implements MethodValidator {
 				}
 
 				Object arg = argumentFunction.apply(parameter.getParameterIndex());
-				if (!itr.hasNext()) {
-					paramViolations
-							.computeIfAbsent(parameter, p -> new ParamResultBuilder(target, parameter, arg))
-							.addViolation(violation);
-				}
-				else {
 
+				// If the arg is a container, we need to element, but the only way to extract it
+				// is to check for and use a container index or key on the next node:
 				// https://github.com/jakartaee/validation/issues/194
-					// If the argument is a container of elements, we need the element, but
-					// the only option is to see if the next part of the property path has
-					// a container index/key for its parent and use it.
 
-					Path.Node paramNode = node;
+				Path.Node parameterNode = node;
+				if (itr.hasNext()) {
 					node = itr.next();
+				}
 
-					Object bean;
+				Object value;
 				Object container;
-					Integer containerIndex = node.getIndex();
+				Integer index = node.getIndex();
-					Object containerKey = node.getKey();
+				Object key = node.getKey();
-					if (containerIndex != null && arg instanceof List<?> list) {
+				if (index != null && arg instanceof List<?> list) {
-						bean = list.get(containerIndex);
+					value = list.get(index);
 					container = list;
 				}
-					else if (containerIndex != null && arg instanceof Object[] array) {
+				else if (index != null && arg instanceof Object[] array) {
-						bean = array[containerIndex];
+					value = array[index];
 					container = array;
 				}
-					else if (containerKey != null && arg instanceof Map<?, ?> map) {
+				else if (key != null && arg instanceof Map<?, ?> map) {
-						bean = map.get(containerKey);
+					value = map.get(key);
 					container = map;
 				}
 				else if (arg instanceof Optional<?> optional) {
-						bean = optional.orElse(null);
+					value = optional.orElse(null);
 					container = optional;
 				}
 				else {
 					Assert.state(!node.isInIterable(), "No way to unwrap Iterable without index");
-						bean = arg;
+					value = arg;
 					container = null;
 				}
 
-					beanViolations
+				if (node.getKind().equals(ElementKind.PROPERTY)) {
-							.computeIfAbsent(paramNode, k ->
+					nestedViolations
-									new BeanResultBuilder(parameter, bean, container, containerIndex, containerKey))
+							.computeIfAbsent(parameterNode, k ->
+									new ParamErrorsBuilder(parameter, value, container, index, key))
 							.addViolation(violation);
 				}
+				else {
+					paramViolations
+							.computeIfAbsent(parameterNode, p ->
+									new ParamValidationResultBuilder(target, parameter, value, container, index, key))
+							.addViolation(violation);
+				}
+
 				break;
 			}
 		}
 
 		List<ParameterValidationResult> resultList = new ArrayList<>();
 		paramViolations.forEach((param, builder) -> resultList.add(builder.build()));
-		beanViolations.forEach((key, builder) -> resultList.add(builder.build()));
+		nestedViolations.forEach((key, builder) -> resultList.add(builder.build()));
 		resultList.sort(resultComparator);
 
 		return MethodValidationResult.create(target, method, resultList);
@@ -430,21 +433,35 @@ public class MethodValidationAdapter implements MethodValidator {
 	 * Builds a validation result for a value method parameter with constraints
 	 * declared directly on it.
 	 */
-	private final class ParamResultBuilder {
+	private final class ParamValidationResultBuilder {
 
 		private final Object target;
 
 		private final MethodParameter parameter;
 
 		@Nullable
-		private final Object argument;
+		private final Object value;
+
+		@Nullable
+		private final Object container;
+
+		@Nullable
+		private final Integer containerIndex;
+
+		@Nullable
+		private final Object containerKey;
 
 		private final List<MessageSourceResolvable> resolvableErrors = new ArrayList<>();
 
-		public ParamResultBuilder(Object target, MethodParameter parameter, @Nullable Object argument) {
+		public ParamValidationResultBuilder(
+				Object target, MethodParameter parameter, @Nullable Object value, @Nullable Object container,
+				@Nullable Integer containerIndex, @Nullable Object containerKey) {
 			this.target = target;
 			this.parameter = parameter;
-			this.argument = argument;
+			this.value = value;
+			this.container = container;
+			this.containerIndex = containerIndex;
+			this.containerKey = containerKey;
 		}
 
 		public void addViolation(ConstraintViolation<Object> violation) {
@@ -452,7 +469,9 @@ public class MethodValidationAdapter implements MethodValidator {
 		}
 
 		public ParameterValidationResult build() {
-			return new ParameterValidationResult(this.parameter, this.argument, this.resolvableErrors);
+			return new ParameterValidationResult(
+					this.parameter, this.value, this.resolvableErrors, this.container,
+					this.containerIndex, this.containerKey);
 		}
 
 	}
@@ -462,7 +481,7 @@ public class MethodValidationAdapter implements MethodValidator {
 	 * Builds a validation result for an {@link jakarta.validation.Valid @Valid}
 	 * annotated bean method parameter with cascaded constraints.
 	 */
-	private final class BeanResultBuilder {
+	private final class ParamErrorsBuilder {
 
 		private final MethodParameter parameter;
 
@@ -482,7 +501,7 @@ public class MethodValidationAdapter implements MethodValidator {
 
 		private final Set<ConstraintViolation<Object>> violations = new LinkedHashSet<>();
 
-		public BeanResultBuilder(
+		public ParamErrorsBuilder(
 				MethodParameter param, @Nullable Object bean, @Nullable Object container,
 				@Nullable Integer containerIndex, @Nullable Object containerKey) {
 

spring-context/src/main/java/org/springframework/validation/method/ParameterErrors.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -32,12 +32,6 @@ import org.springframework.validation.ObjectError;
  * {@link Errors#getAllErrors()}, but this subclass provides access to the same
  * as {@link FieldError}s.
  *
- * <p>When the method parameter is a container such as a {@link List}, array,
- * or {@link java.util.Map}, then a separate {@link ParameterErrors} is created
- * for each element that has errors. In that case, the properties
- * {@link #getContainer() container}, {@link #getContainerIndex() containerIndex},
- * and {@link #getContainerKey() containerKey} provide additional context.
- *
  * @author Rossen Stoyanchev
  * @since 6.1
  */
@@ -45,15 +39,6 @@ public class ParameterErrors extends ParameterValidationResult implements Errors
 
 	private final Errors errors;
 
-	@Nullable
-	private final Object container;
-
-	@Nullable
-	private final Integer containerIndex;
-
-	@Nullable
-	private final Object containerKey;
-
 
 	/**
 	 * Create a {@code ParameterErrors}.
@@ -62,45 +47,8 @@ public class ParameterErrors extends ParameterValidationResult implements Errors
 			MethodParameter parameter, @Nullable Object argument, Errors errors,
 			@Nullable Object container, @Nullable Integer index, @Nullable Object key) {
 
-		super(parameter, argument, errors.getAllErrors());
+		super(parameter, argument, errors.getAllErrors(), container, index, key);
 		this.errors = errors;
-		this.container = container;
-		this.containerIndex = index;
-		this.containerKey = key;
-	}
-
-
-	/**
-	 * When {@code @Valid} is declared on a container of elements such as
-	 * {@link java.util.Collection}, {@link java.util.Map},
-	 * {@link java.util.Optional}, and others, this method returns the container
-	 * of the validated {@link #getArgument() argument}, while
-	 * {@link #getContainerIndex()} and {@link #getContainerKey()} provide
-	 * information about the index or key if applicable.
-	 */
-	@Nullable
-	public Object getContainer() {
-		return this.container;
-	}
-
-	/**
-	 * When {@code @Valid} is declared on an indexed container of elements such as
-	 * {@link List} or array, this method returns the index of the validated
-	 * {@link #getArgument() argument}.
-	 */
-	@Nullable
-	public Integer getContainerIndex() {
-		return this.containerIndex;
-	}
-
-	/**
-	 * When {@code @Valid} is declared on a container of elements referenced by
-	 * key such as {@link java.util.Map}, this method returns the key of the
-	 * validated {@link #getArgument() argument}.
-	 */
-	@Nullable
-	public Object getContainerKey() {
-		return this.containerKey;
 	}
 
 

spring-context/src/main/java/org/springframework/validation/method/ParameterValidationResult.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -35,6 +35,12 @@ import org.springframework.util.ObjectUtils;
  * {@link ParameterErrors}.
  * </ul>
  *
+ * <p>When the method parameter is a container such as a {@link List}, array,
+ * or {@link java.util.Map}, then a separate {@link ParameterValidationResult}
+ * is created for each element with errors. In that case, the properties
+ * {@link #getContainer() container}, {@link #getContainerIndex() containerIndex},
+ * and {@link #getContainerKey() containerKey} provide additional context.
+ *
  * @author Rossen Stoyanchev
  * @since 6.1
  */
@@ -47,18 +53,43 @@ public class ParameterValidationResult {
 
 	private final List<MessageSourceResolvable> resolvableErrors;
 
+	@Nullable
+	private final Object container;
+
+	@Nullable
+	private final Integer containerIndex;
+
+	@Nullable
+	private final Object containerKey;
+
 
 	/**
 	 * Create a {@code ParameterValidationResult}.
 	 */
 	public ParameterValidationResult(
-			MethodParameter param, @Nullable Object arg, Collection<? extends MessageSourceResolvable> errors) {
+			MethodParameter param, @Nullable Object arg, Collection<? extends MessageSourceResolvable> errors,
+			@Nullable Object container, @Nullable Integer index, @Nullable Object key) {
 
 		Assert.notNull(param, "MethodParameter is required");
 		Assert.notEmpty(errors, "`resolvableErrors` must not be empty");
 		this.methodParameter = param;
 		this.argument = arg;
 		this.resolvableErrors = List.copyOf(errors);
+		this.container = container;
+		this.containerIndex = index;
+		this.containerKey = key;
+	}
+
+	/**
+	 * Create a {@code ParameterValidationResult}.
+	 * @deprecated in favor of
+	 * {@link ParameterValidationResult#ParameterValidationResult(MethodParameter, Object, Collection, Object, Integer, Object)}
+	 */
+	@Deprecated(since = "6.1.3", forRemoval = true)
+	public ParameterValidationResult(
+			MethodParameter param, @Nullable Object arg, Collection<? extends MessageSourceResolvable> errors) {
+
+		this(param, arg, errors, null, null, null);
 	}
 
 
@@ -100,6 +131,39 @@ public class ParameterValidationResult {
 		return this.resolvableErrors;
 	}
 
+	/**
+	 * When {@code @Valid} is declared on a container of elements such as
+	 * {@link java.util.Collection}, {@link java.util.Map},
+	 * {@link java.util.Optional}, and others, this method returns the container
+	 * of the validated {@link #getArgument() argument}, while
+	 * {@link #getContainerIndex()} and {@link #getContainerKey()} provide
+	 * information about the index or key if applicable.
+	 */
+	@Nullable
+	public Object getContainer() {
+		return this.container;
+	}
+
+	/**
+	 * When {@code @Valid} is declared on an indexed container of elements such as
+	 * {@link List} or array, this method returns the index of the validated
+	 * {@link #getArgument() argument}.
+	 */
+	@Nullable
+	public Integer getContainerIndex() {
+		return this.containerIndex;
+	}
+
+	/**
+	 * When {@code @Valid} is declared on a container of elements referenced by
+	 * key such as {@link java.util.Map}, this method returns the key of the
+	 * validated {@link #getArgument() argument}.
+	 */
+	@Nullable
+	public Object getContainerKey() {
+		return this.containerKey;
+	}
+
 
 	@Override
 	public boolean equals(@Nullable Object other) {
@@ -111,7 +175,9 @@ public class ParameterValidationResult {
 		}
 		ParameterValidationResult otherResult = (ParameterValidationResult) other;
 		return (getMethodParameter().equals(otherResult.getMethodParameter()) &&
-				ObjectUtils.nullSafeEquals(getArgument(), otherResult.getArgument()));
+				ObjectUtils.nullSafeEquals(getArgument(), otherResult.getArgument()) &&
+				ObjectUtils.nullSafeEquals(getContainerIndex(), otherResult.getContainerIndex()) &&
+				ObjectUtils.nullSafeEquals(getContainerKey(), otherResult.getContainerKey()));
 	}
 
 	@Override
@@ -119,14 +185,18 @@ public class ParameterValidationResult {
 		int hashCode = super.hashCode();
 		hashCode = 29 * hashCode + getMethodParameter().hashCode();
 		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getArgument());
+		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getContainerIndex());
+		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getContainerKey());
 		return hashCode;
 	}
 
 	@Override
 	public String toString() {
-		return "Validation results for method parameter '" + this.methodParameter +
+		return getClass().getSimpleName() + " for " + this.methodParameter +
-				"': argument [" + ObjectUtils.nullSafeConciseToString(this.argument) + "]; " +
+				", argument value '" + ObjectUtils.nullSafeConciseToString(this.argument) + "'," +
-				getResolvableErrors();
+				(this.containerIndex != null ? "containerIndex[" + this.containerIndex + "]," : "") +
+				(this.containerKey != null ? "containerKey['" + this.containerKey + "']," : "") +
+				" errors: " + getResolvableErrors();
 	}
 
 }

spring-context/src/test/java/org/springframework/validation/beanvalidation/MethodValidationAdapterTests.java

@@ -161,7 +161,7 @@ class MethodValidationAdapterTests {
 	}
 
 	@Test
-	void validateListArgument() {
+	void validateBeanListArgument() {
 		MyService target = new MyService();
 		Method method = getMethod(target, "addPeople");
 
@@ -195,6 +195,24 @@ class MethodValidationAdapterTests {
 		});
 	}
 
+	@Test
+	void validateValueListArgument() {
+		MyService target = new MyService();
+		Method method = getMethod(target, "addHobbies");
+
+		testArgs(target, method, new Object[] {List.of("   ")}, ex -> {
+
+			assertThat(ex.getAllValidationResults()).hasSize(1);
+
+			assertValueResult(ex.getValueResults().get(0), 0, "   ", List.of("""
+				org.springframework.context.support.DefaultMessageSourceResolvable: \
+				codes [NotBlank.myService#addHobbies.hobbies,NotBlank.hobbies,NotBlank.java.util.List,NotBlank]; \
+				arguments [org.springframework.context.support.DefaultMessageSourceResolvable: \
+				codes [myService#addHobbies.hobbies,hobbies]; \
+				arguments []; default message [hobbies]]; default message [must not be blank]"""));
+		});
+	}
+
 	private void testArgs(Object target, Method method, Object[] args, Consumer<MethodValidationResult> consumer) {
 		consumer.accept(this.validationAdapter.validateArguments(target, method, null, args, new Class<?>[0]));
 	}
@@ -250,6 +268,9 @@ class MethodValidationAdapterTests {
 		public void addPeople(@Valid List<Person> people) {
 		}
 
+		public void addHobbies(List<@NotBlank String> hobbies) {
+		}
+
 	}
 
 

spring-web/src/test/java/org/springframework/web/method/support/HandlerMethodValidationExceptionTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -128,7 +128,7 @@ public class HandlerMethodValidationExceptionTests {
 							}
 							else {
 								MessageSourceResolvable error = new DefaultMessageSourceResolvable("Size");
-								return new ParameterValidationResult(param, "123", List.of(error));
+								return new ParameterValidationResult(param, "123", List.of(error), null, null, null);
 							}
 						})
 						.toList());