/*
* Copyright 2002-2018 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.web.method.annotation;
import java.beans.ConstructorProperties;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.TypeMismatchException;
import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.core.MethodParameter;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.validation.BindException;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.validation.SmartValidator;
import org.springframework.validation.Validator;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.bind.support.WebRequestDataBinder;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
import org.springframework.web.method.support.ModelAndViewContainer;
/**
* Resolve {@code @ModelAttribute} annotated method arguments and handle
* return values from {@code @ModelAttribute} annotated methods.
*
* <p>Model attributes are obtained from the model or created with a default
* constructor (and then added to the model). Once created the attribute is
* populated via data binding to Servlet request parameters. Validation may be
* applied if the argument is annotated with {@code @javax.validation.Valid}.
* or Spring's own {@code @org.springframework.validation.annotation.Validated}.
*
* <p>When this handler is created with {@code annotationNotRequired=true}
* any non-simple type argument and return value is regarded as a model
* attribute with or without the presence of an {@code @ModelAttribute}.
*
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @author Sebastien Deleuze
* @since 3.1
*/
public class ModelAttributeMethodProcessor implements HandlerMethodArgumentResolver, HandlerMethodReturnValueHandler {
private static final ParameterNameDiscoverer parameterNameDiscoverer = new DefaultParameterNameDiscoverer();
protected final Log logger = LogFactory.getLog(getClass());
private final boolean annotationNotRequired;
/**
* Class constructor.
* @param annotationNotRequired if "true", non-simple method arguments and
* return values are considered model attributes with or without a
* {@code @ModelAttribute} annotation
*/
public ModelAttributeMethodProcessor(boolean annotationNotRequired) {
this.annotationNotRequired = annotationNotRequired;
}
/**
* Returns {@code true} if the parameter is annotated with
* {@link ModelAttribute} or, if in default resolution mode, for any
* method parameter that is not a simple type.
*/
@Override
public boolean supportsParameter(MethodParameter parameter) {
return (parameter.hasParameterAnnotation(ModelAttribute.class) ||
(this.annotationNotRequired && !BeanUtils.isSimpleProperty(parameter.getParameterType())));
}
/**
* Resolve the argument from the model or if not found instantiate it with
* its default if it is available. The model attribute is then populated
* with request values via data binding and optionally validated
* if {@code @java.validation.Valid} is present on the argument.
* @throws BindException if data binding and validation result in an error
* and the next method parameter is not of type {@link Errors}
* @throws Exception if WebDataBinder initialization fails
*/
@Override
@Nullable
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
Assert.state(mavContainer != null, "ModelAttributeMethodProcessor requires ModelAndViewContainer");
Assert.state(binderFactory != null, "ModelAttributeMethodProcessor requires WebDataBinderFactory");
String name = ModelFactory.getNameForParameter(parameter);
ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
if (ann != null) {
mavContainer.setBinding(name, ann.binding());
}
Object attribute = null;
BindingResult bindingResult = null;
if (mavContainer.containsAttribute(name)) {
attribute = mavContainer.getModel().get(name);
}
else {
// Create attribute instance
try {
attribute = createAttribute(name, parameter, binderFactory, webRequest);
}
catch (BindException ex) {
if (isBindExceptionRequired(parameter)) {
// No BindingResult parameter -> fail with BindException
throw ex;
}
// Otherwise, expose null/empty value and associated BindingResult
if (parameter.getParameterType() == Optional.class) {
attribute = Optional.empty();
}
bindingResult = ex.getBindingResult();
}
}
if (bindingResult == null) {
// Bean property binding and validation;
// skipped in case of binding failure on construction.
WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
if (binder.getTarget() != null) {
if (!mavContainer.isBindingDisabled(name)) {
bindRequestParameters(binder, webRequest);
}
validateIfApplicable(binder, parameter);
if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
throw new BindException(binder.getBindingResult());
}
}
// Value type adaptation, also covering java.util.Optional
if (!parameter.getParameterType().isInstance(attribute)) {
attribute = binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);
}
bindingResult = binder.getBindingResult();
}
// Add resolved attribute and BindingResult at the end of the model
Map<String, Object> bindingResultModel = bindingResult.getModel();
mavContainer.removeAttributes(bindingResultModel);
mavContainer.addAllAttributes(bindingResultModel);
return attribute;
}
/**
* Extension point to create the model attribute if not found in the model,
* with subsequent parameter binding through bean properties (unless suppressed).
* <p>The default implementation typically uses the unique public no-arg constructor
* if available but also handles a "primary constructor" approach for data classes:
* It understands the JavaBeans {@link ConstructorProperties} annotation as well as
* runtime-retained parameter names in the bytecode, associating request parameters
* with constructor arguments by name. If no such constructor is found, the default
* constructor will be used (even if not public), assuming subsequent bean property
* bindings through setter methods.
* @param attributeName the name of the attribute (never {@code null})
* @param parameter the method parameter declaration
* @param binderFactory for creating WebDataBinder instance
* @param webRequest the current request
* @return the created model attribute (never {@code null})
* @throws BindException in case of constructor argument binding failure
* @throws Exception in case of constructor invocation failure
* @see #constructAttribute(Constructor, String, MethodParameter, WebDataBinderFactory, NativeWebRequest)
* @see BeanUtils#findPrimaryConstructor(Class)
*/
protected Object createAttribute(String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest webRequest) throws Exception {
MethodParameter nestedParameter = parameter.nestedIfOptional();
Class<?> clazz = nestedParameter.getNestedParameterType();
Constructor<?> ctor = BeanUtils.findPrimaryConstructor(clazz);
if (ctor == null) {
Constructor<?>[] ctors = clazz.getConstructors();
if (ctors.length == 1) {
ctor = ctors[0];
}
else {
try {
ctor = clazz.getDeclaredConstructor();
}
catch (NoSuchMethodException ex) {
throw new IllegalStateException("No primary or default constructor found for " + clazz, ex);
}
}
}
Object attribute = constructAttribute(ctor, attributeName, parameter, binderFactory, webRequest);
if (parameter != nestedParameter) {
attribute = Optional.of(attribute);
}
return attribute;
}
/**
* Construct a new attribute instance with the given constructor.
* <p>Called from
* {@link #createAttribute(String, MethodParameter, WebDataBinderFactory, NativeWebRequest)}
* after constructor resolution.
* @param ctor the constructor to use
* @param attributeName the name of the attribute (never {@code null})
* @param binderFactory for creating WebDataBinder instance
* @param webRequest the current request
* @return the created model attribute (never {@code null})
* @throws BindException in case of constructor argument binding failure
* @throws Exception in case of constructor invocation failure
* @since 5.1
*/
@SuppressWarnings("deprecation")
protected Object constructAttribute(Constructor<?> ctor, String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest webRequest) throws Exception {
Object constructed = constructAttribute(ctor, attributeName, binderFactory, webRequest);
if (constructed != null) {
return constructed;
}
if (ctor.getParameterCount() == 0) {
// A single default constructor -> clearly a standard JavaBeans arrangement.
return BeanUtils.instantiateClass(ctor);
}
// A single data class constructor -> resolve constructor arguments from request parameters.
ConstructorProperties cp = ctor.getAnnotation(ConstructorProperties.class);
String[] paramNames = (cp != null ? cp.value() : parameterNameDiscoverer.getParameterNames(ctor));
Assert.state(paramNames != null, () -> "Cannot resolve parameter names for constructor " + ctor);
Class<?>[] paramTypes = ctor.getParameterTypes();
Assert.state(paramNames.length == paramTypes.length,
() -> "Invalid number of parameter names: " + paramNames.length + " for constructor " + ctor);
Object[] args = new Object[paramTypes.length];
WebDataBinder binder = binderFactory.createBinder(webRequest, null, attributeName);
String fieldDefaultPrefix = binder.getFieldDefaultPrefix();
String fieldMarkerPrefix = binder.getFieldMarkerPrefix();
boolean bindingFailure = false;
Set<String> failedParams = new HashSet<>(4);
for (int i = 0; i < paramNames.length; i++) {
String paramName = paramNames[i];
Class<?> paramType = paramTypes[i];
Object value = webRequest.getParameterValues(paramName);
if (value == null) {
if (fieldDefaultPrefix != null) {
value = webRequest.getParameter(fieldDefaultPrefix + paramName);
}
if (value == null && fieldMarkerPrefix != null) {
if (webRequest.getParameter(fieldMarkerPrefix + paramName) != null) {
value = binder.getEmptyValue(paramType);
}
}
}
try {
MethodParameter methodParam = new FieldAwareConstructorParameter(ctor, i, paramName);
if (value == null && methodParam.isOptional()) {
args[i] = (methodParam.getParameterType() == Optional.class ? Optional.empty() : null);
}
else {
args[i] = binder.convertIfNecessary(value, paramType, methodParam);
}
}
catch (TypeMismatchException ex) {
ex.initPropertyName(paramName);
args[i] = value;
failedParams.add(paramName);
binder.getBindingResult().recordFieldValue(paramName, paramType, value);
binder.getBindingErrorProcessor().processPropertyAccessException(ex, binder.getBindingResult());
bindingFailure = true;
}
}
if (bindingFailure) {
BindingResult result = binder.getBindingResult();
for (int i = 0; i < paramNames.length; i++) {
String paramName = paramNames[i];
if (!failedParams.contains(paramName)) {
Object value = args[i];
result.recordFieldValue(paramName, paramTypes[i], value);
validateValueIfApplicable(binder, parameter, ctor.getDeclaringClass(), paramName, value);
}
}
throw new BindException(result);
}
return BeanUtils.instantiateClass(ctor, args);
}
/**
* Construct a new attribute instance with the given constructor.
* @since 5.0
* @deprecated as of 5.1, in favor of
* {@link #constructAttribute(Constructor, String, MethodParameter, WebDataBinderFactory, NativeWebRequest)}
*/
@Deprecated
@Nullable
protected Object constructAttribute(Constructor<?> ctor, String attributeName,
WebDataBinderFactory binderFactory, NativeWebRequest webRequest) throws Exception {
return null;
}
/**
* Extension point to bind the request to the target object.
* @param binder the data binder instance to use for the binding
* @param request the current request
*/
protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest request) {
((WebRequestDataBinder) binder).bind(request);
}
/**
* Validate the model attribute if applicable.
* <p>The default implementation checks for {@code @javax.validation.Valid},
* Spring's {@link org.springframework.validation.annotation.Validated},
* and custom annotations whose name starts with "Valid".
* @param binder the DataBinder to be used
* @param parameter the method parameter declaration
* @see WebDataBinder#validate(Object...)
* @see SmartValidator#validate(Object, Errors, Object...)
*/
protected void validateIfApplicable(WebDataBinder binder, MethodParameter parameter) {
for (Annotation ann : parameter.getParameterAnnotations()) {
Object[] validationHints = determineValidationHints(ann);
if (validationHints != null) {
binder.validate(validationHints);
break;
}
}
}
/**
* Validate the specified candidate value if applicable.
* <p>The default implementation checks for {@code @javax.validation.Valid},
* Spring's {@link org.springframework.validation.annotation.Validated},
* and custom annotations whose name starts with "Valid".
* @param binder the DataBinder to be used
* @param parameter the method parameter declaration
* @param targetType the target type
* @param fieldName the name of the field
* @param value the candidate value
* @since 5.1
* @see #validateIfApplicable(WebDataBinder, MethodParameter)
* @see SmartValidator#validateValue(Class, String, Object, Errors, Object...)
*/
protected void validateValueIfApplicable(WebDataBinder binder, MethodParameter parameter,
Class<?> targetType, String fieldName, @Nullable Object value) {
for (Annotation ann : parameter.getParameterAnnotations()) {
Object[] validationHints = determineValidationHints(ann);
if (validationHints != null) {
for (Validator validator : binder.getValidators()) {
if (validator instanceof SmartValidator) {
try {
((SmartValidator) validator).validateValue(targetType, fieldName, value,
binder.getBindingResult(), validationHints);
}
catch (IllegalArgumentException ex) {
// No corresponding field on the target class...
}
}
}
break;
}
}
}
/**
* Determine any validation triggered by the given annotation.
* @param ann the annotation (potentially a validation annotation)
* @return the validation hints to apply (possibly an empty array),
* or {@code null} if this annotation does not trigger any validation
* @since 5.1
*/
@Nullable
private Object[] determineValidationHints(Annotation ann) {
Validated validatedAnn = AnnotationUtils.getAnnotation(ann, Validated.class);
if (validatedAnn != null || ann.annotationType().getSimpleName().startsWith("Valid")) {
Object hints = (validatedAnn != null ? validatedAnn.value() : AnnotationUtils.getValue(ann));
if (hints == null) {
return new Object[0];
}
return (hints instanceof Object[] ? (Object[]) hints : new Object[] {hints});
}
return null;
}
/**
* Whether to raise a fatal bind exception on validation errors.
* <p>The default implementation delegates to {@link #isBindExceptionRequired(MethodParameter)}.
* @param binder the data binder used to perform data binding
* @param parameter the method parameter declaration
* @return {@code true} if the next method parameter is not of type {@link Errors}
* @see #isBindExceptionRequired(MethodParameter)
*/
protected boolean isBindExceptionRequired(WebDataBinder binder, MethodParameter parameter) {
return isBindExceptionRequired(parameter);
}
/**
* Whether to raise a fatal bind exception on validation errors.
* @param parameter the method parameter declaration
* @return {@code true} if the next method parameter is not of type {@link Errors}
* @since 5.0
*/
protected boolean isBindExceptionRequired(MethodParameter parameter) {
int i = parameter.getParameterIndex();
Class<?>[] paramTypes = parameter.getExecutable().getParameterTypes();
boolean hasBindingResult = (paramTypes.length > (i + 1) && Errors.class.isAssignableFrom(paramTypes[i + 1]));
return !hasBindingResult;
}
/**
* Return {@code true} if there is a method-level {@code @ModelAttribute}
* or, in default resolution mode, for any return value type that is not
* a simple type.
*/
@Override
public boolean supportsReturnType(MethodParameter returnType) {
return (returnType.hasMethodAnnotation(ModelAttribute.class) ||
(this.annotationNotRequired && !BeanUtils.isSimpleProperty(returnType.getParameterType())));
}
/**
* Add non-null return values to the {@link ModelAndViewContainer}.
*/
@Override
public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType,
ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
if (returnValue != null) {
String name = ModelFactory.getNameForReturnValue(returnValue, returnType);
mavContainer.addAttribute(name, returnValue);
}
}
/**
* {@link MethodParameter} subclass which detects field annotations as well.
* @since 5.1
*/
private static class FieldAwareConstructorParameter extends MethodParameter {
private final String parameterName;
@Nullable
private volatile Annotation[] combinedAnnotations;
public FieldAwareConstructorParameter(Constructor<?> constructor, int parameterIndex, String parameterName) {
super(constructor, parameterIndex);
this.parameterName = parameterName;
}
@Override
public Annotation[] getParameterAnnotations() {
Annotation[] anns = this.combinedAnnotations;
if (anns == null) {
anns = super.getParameterAnnotations();
try {
Field field = getDeclaringClass().getDeclaredField(this.parameterName);
Annotation[] fieldAnns = field.getAnnotations();
if (fieldAnns.length > 0) {
List<Annotation> merged = new ArrayList<>(anns.length + fieldAnns.length);
merged.addAll(Arrays.asList(anns));
for (Annotation fieldAnn : fieldAnns) {
boolean existingType = false;
for (Annotation ann : anns) {
if (ann.annotationType() == fieldAnn.annotationType()) {
existingType = true;
break;
}
}
if (!existingType) {
merged.add(fieldAnn);
}
}
anns = merged.toArray(new Annotation[0]);
}
}
catch (NoSuchFieldException | SecurityException ex) {
// ignore
}
this.combinedAnnotations = anns;
}
return anns;
}
@Override
public String getParameterName() {
return this.parameterName;
}
}
}
