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Support nested constructors in DataBinder
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Closes gh-20806
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@rstoyanchev
rstoyanchev committed Jun 26, 2023
1 parent 11a4161 commit d4ac90d
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Showing 2 changed files with 328 additions and 51 deletions.
130 changes: 80 additions & 50 deletions spring-context/src/main/java/org/springframework/validation/DataBinder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -850,106 +850,136 @@ public final void construct(ValueResolver valueResolver) {
Assert.state(this.target == null, "Target instance already available");
Assert.state(this.targetType != null, "Target type not set");

Class<?> clazz = this.targetType.resolve();
clazz = (Optional.class.equals(clazz) ? this.targetType.resolveGeneric(0) : clazz);
Assert.state(clazz != null, "Unknown data binding target type");
this.target = createObject(this.targetType, "", valueResolver);

if (!getBindingResult().hasErrors()) {
this.bindingResult = null;
if (this.typeConverter != null) {
this.typeConverter.registerCustomEditors(getPropertyAccessor());
}
}
}

@Nullable
private Object createObject(ResolvableType objectType, String nestedPath, ValueResolver valueResolver) {
Class<?> clazz = objectType.resolve();
boolean isOptional = (clazz == Optional.class);
clazz = (isOptional ? objectType.resolveGeneric(0) : clazz);
if (clazz == null) {
throw new IllegalStateException(
"Insufficient type information to create instance of " + objectType);
}

Object result = null;
Constructor<?> ctor = BeanUtils.getResolvableConstructor(clazz);

if (ctor.getParameterCount() == 0) {
// A single default constructor -> clearly a standard JavaBeans arrangement.
this.target = BeanUtils.instantiateClass(ctor);
result = BeanUtils.instantiateClass(ctor);
}
else {
// A single data class constructor -> resolve constructor arguments from request parameters.
String[] paramNames = BeanUtils.getParameterNames(ctor);
Class<?>[] paramTypes = ctor.getParameterTypes();
Object[] args = new Object[paramTypes.length];
Set<String> failedParamNames = new HashSet<>(4);
boolean bindFailure = false;

for (int i = 0; i < paramNames.length; i++) {
String paramName = paramNames[i];
String paramPath = nestedPath + paramNames[i];
Class<?> paramType = paramTypes[i];
Object value = valueResolver.resolveValue(paramName, paramType);
try {
MethodParameter methodParam = MethodParameter.forFieldAwareConstructor(ctor, i, paramName);
if (value == null && methodParam.isOptional()) {
args[i] = (methodParam.getParameterType() == Optional.class ? Optional.empty() : null);
Object value = valueResolver.resolveValue(paramPath, paramType);

MethodParameter param = MethodParameter.forFieldAwareConstructor(ctor, i, paramNames[i]);
if (value == null && !BeanUtils.isSimpleValueType(param.nestedIfOptional().getNestedParameterType())) {
ResolvableType type = ResolvableType.forMethodParameter(param);
args[i] = createObject(type, paramPath + ".", valueResolver);
}
else {
try {
if (value == null && (param.isOptional() || getBindingResult().hasErrors())) {
args[i] = (param.getParameterType() == Optional.class ? Optional.empty() : null);
}
else {
args[i] = convertIfNecessary(value, paramType, param);
}
}
else {
args[i] = convertIfNecessary(value, paramType, methodParam);
catch (TypeMismatchException ex) {
ex.initPropertyName(paramPath);
args[i] = null;
failedParamNames.add(paramPath);
getBindingResult().recordFieldValue(paramPath, paramType, value);
getBindingErrorProcessor().processPropertyAccessException(ex, getBindingResult());
}
}
catch (TypeMismatchException ex) {
ex.initPropertyName(paramName);
args[i] = null;
failedParamNames.add(paramName);
getBindingResult().recordFieldValue(paramName, paramType, value);
getBindingErrorProcessor().processPropertyAccessException(ex, getBindingResult());
bindFailure = true;
}
}

if (bindFailure) {
if (getBindingResult().hasErrors()) {
for (int i = 0; i < paramNames.length; i++) {
String paramName = paramNames[i];
if (!failedParamNames.contains(paramName)) {
String paramPath = nestedPath + paramNames[i];
if (!failedParamNames.contains(paramPath)) {
Object value = args[i];
getBindingResult().recordFieldValue(paramName, paramTypes[i], value);
validateArgument(ctor.getDeclaringClass(), paramName, value);
getBindingResult().recordFieldValue(paramPath, paramTypes[i], value);
validateConstructorArgument(ctor.getDeclaringClass(), nestedPath, paramNames[i], value);
}
}
if (!(this.targetType.getSource() instanceof MethodParameter param && param.isOptional())) {
if (!(objectType.getSource() instanceof MethodParameter param && param.isOptional())) {
try {
this.target = BeanUtils.instantiateClass(ctor, args);
result = BeanUtils.instantiateClass(ctor, args);
}
catch (BeanInstantiationException ex) {
// swallow and proceed without target instance
}
}
return;
}

try {
this.target = BeanUtils.instantiateClass(ctor, args);
}
catch (BeanInstantiationException ex) {
if (KotlinDetector.isKotlinType(clazz) && ex.getCause() instanceof NullPointerException cause) {
ObjectError error = new ObjectError(ctor.getName(), cause.getMessage());
getBindingResult().addError(error);
return;
else {
try {
result = BeanUtils.instantiateClass(ctor, args);
}
catch (BeanInstantiationException ex) {
if (KotlinDetector.isKotlinType(clazz) && ex.getCause() instanceof NullPointerException cause) {
ObjectError error = new ObjectError(ctor.getName(), cause.getMessage());
getBindingResult().addError(error);
}
else {
throw ex;
}
}
throw ex;
}
}

// Now that target is set, add PropertyEditor's to PropertyAccessor
if (this.typeConverter != null) {
this.typeConverter.registerCustomEditors(getPropertyAccessor());
}
return (isOptional && !nestedPath.isEmpty() ? Optional.ofNullable(result) : result);
}

private void validateArgument(Class<?> constructorClass, String name, @Nullable Object value) {
Object[] validationHints = null;
private void validateConstructorArgument(
Class<?> constructorClass, String nestedPath, String name, @Nullable Object value) {

Object[] hints = null;
if (this.targetType.getSource() instanceof MethodParameter parameter) {
for (Annotation ann : parameter.getParameterAnnotations()) {
validationHints = ValidationAnnotationUtils.determineValidationHints(ann);
if (validationHints != null) {
hints = ValidationAnnotationUtils.determineValidationHints(ann);
if (hints != null) {
break;
}
}
}
if (validationHints == null) {
if (hints == null) {
return;
}
for (Validator validator : getValidatorsToApply()) {
if (validator instanceof SmartValidator smartValidator) {
boolean isNested = !nestedPath.isEmpty();
if (isNested) {
getBindingResult().pushNestedPath(nestedPath.substring(0, nestedPath.length() - 1));
}
try {
smartValidator.validateValue(
constructorClass, name, value, getBindingResult(), validationHints);
smartValidator.validateValue(constructorClass, name, value, getBindingResult(), hints);
}
catch (IllegalArgumentException ex) {
// No corresponding field on the target class...
}
if (isNested) {
getBindingResult().popNestedPath();
}
}
}
}
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