/*
* Copyright 2002-2017 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
*
* http://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.reactive.result.method.annotation;
import java.beans.ConstructorProperties;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import reactor.core.publisher.Mono;
import reactor.core.publisher.MonoProcessor;
import org.springframework.beans.BeanUtils;
import org.springframework.core.Conventions;
import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.core.MethodParameter;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.core.ReactiveAdapter;
import org.springframework.core.ReactiveAdapterRegistry;
import org.springframework.core.ResolvableType;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.ui.Model;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
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.WebExchangeBindException;
import org.springframework.web.bind.support.WebExchangeDataBinder;
import org.springframework.web.reactive.BindingContext;
import org.springframework.web.reactive.result.method.HandlerMethodArgumentResolverSupport;
import org.springframework.web.server.ServerWebExchange;
/**
* Resolve {@code @ModelAttribute} annotated method arguments.
*
* <p>Model attributes are sourced from the model, or created using a default
* constructor and then added to the model. Once created the attribute is
* populated via data binding to the request (form data, query params).
* Validation also 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 useDefaultResolution=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
* @since 5.0
*/
public class ModelAttributeMethodArgumentResolver extends HandlerMethodArgumentResolverSupport {
private static final ParameterNameDiscoverer parameterNameDiscoverer = new DefaultParameterNameDiscoverer();
private final boolean useDefaultResolution;
/**
* Class constructor with a default resolution mode flag.
* @param adapterRegistry for adapting to other reactive types from and to Mono
* @param useDefaultResolution if "true", non-simple method arguments and
* return values are considered model attributes with or without a
* {@code @ModelAttribute} annotation present.
*/
public ModelAttributeMethodArgumentResolver(ReactiveAdapterRegistry adapterRegistry,
boolean useDefaultResolution) {
super(adapterRegistry);
this.useDefaultResolution = useDefaultResolution;
}
@Override
public boolean supportsParameter(MethodParameter parameter) {
if (parameter.hasParameterAnnotation(ModelAttribute.class)) {
return true;
}
else if (this.useDefaultResolution) {
return checkParameterType(parameter, type -> !BeanUtils.isSimpleProperty(type));
}
return false;
}
@Override
public Mono<Object> resolveArgument(
MethodParameter parameter, BindingContext context, ServerWebExchange exchange) {
ResolvableType type = ResolvableType.forMethodParameter(parameter);
ReactiveAdapter adapter = getAdapterRegistry().getAdapter(type.resolve());
ResolvableType valueType = (adapter != null ? type.getGeneric(0) : type);
Assert.state(adapter == null || !adapter.isMultiValue(),
() -> getClass().getSimpleName() + " doesn't support multi-value reactive type wrapper: " +
parameter.getGenericParameterType());
String name = getAttributeName(parameter);
Mono<?> valueMono = prepareAttributeMono(name, valueType, context, exchange);
Map<String, Object> model = context.getModel().asMap();
MonoProcessor<BindingResult> bindingResultMono = MonoProcessor.create();
model.put(BindingResult.MODEL_KEY_PREFIX + name, bindingResultMono);
return valueMono.flatMap(value -> {
WebExchangeDataBinder binder = context.createDataBinder(exchange, value, name);
return binder.bind(exchange)
.doOnError(bindingResultMono::onError)
.doOnSuccess(aVoid -> {
validateIfApplicable(binder, parameter);
BindingResult errors = binder.getBindingResult();
model.put(BindingResult.MODEL_KEY_PREFIX + name, errors);
model.put(name, value);
bindingResultMono.onNext(errors);
})
.then(Mono.fromCallable(() -> {
BindingResult errors = binder.getBindingResult();
if (adapter != null) {
return adapter.fromPublisher(errors.hasErrors() ?
Mono.error(new WebExchangeBindException(parameter, errors)) :
valueMono);
}
else {
if (errors.hasErrors() && !hasErrorsArgument(parameter)) {
throw new WebExchangeBindException(parameter, errors);
}
return value;
}
}));
});
}
private String getAttributeName(MethodParameter parameter) {
return Optional.ofNullable(parameter.getParameterAnnotation(ModelAttribute.class))
.filter(ann -> StringUtils.hasText(ann.value()))
.map(ModelAttribute::value)
.orElse(Conventions.getVariableNameForParameter(parameter));
}
private Mono<?> prepareAttributeMono(String attributeName, ResolvableType attributeType,
BindingContext context, ServerWebExchange exchange) {
Object attribute = context.getModel().asMap().get(attributeName);
if (attribute == null) {
attribute = findAndRemoveReactiveAttribute(context.getModel(), attributeName);
}
if (attribute == null) {
return createAttribute(attributeName, attributeType.getRawClass(), context, exchange);
}
ReactiveAdapter adapterFrom = getAdapterRegistry().getAdapter(null, attribute);
if (adapterFrom != null) {
Assert.isTrue(!adapterFrom.isMultiValue(), "Data binding only supports single-value async types");
return Mono.from(adapterFrom.toPublisher(attribute));
}
else {
return Mono.justOrEmpty(attribute);
}
}
private Object findAndRemoveReactiveAttribute(Model model, String attributeName) {
return model.asMap().entrySet().stream()
.filter(entry -> {
if (!entry.getKey().startsWith(attributeName)) {
return false;
}
ReactiveAdapter adapter = getAdapterRegistry().getAdapter(null, entry.getValue());
if (adapter == null) {
return false;
}
String name = attributeName + ClassUtils.getShortName(adapter.getReactiveType());
return entry.getKey().equals(name);
})
.findFirst()
.map(entry -> {
// Remove since we will be re-inserting the resolved attribute value
model.asMap().remove(entry.getKey());
return entry.getValue();
})
.orElse(null);
}
private Mono<?> createAttribute(
String attributeName, Class<?> attributeType, BindingContext context, ServerWebExchange exchange) {
Constructor<?>[] ctors = attributeType.getConstructors();
if (ctors.length != 1) {
// No standard data class or standard JavaBeans arrangement ->
// defensively go with default constructor, expecting regular bean property bindings.
return Mono.just(BeanUtils.instantiateClass(attributeType));
}
Constructor<?> ctor = ctors[0];
if (ctor.getParameterCount() == 0) {
// A single default constructor -> clearly a standard JavaBeans arrangement.
return Mono.just(BeanUtils.instantiateClass(ctor));
}
// A single data class constructor -> resolve constructor arguments from request parameters.
return WebExchangeDataBinder.extractValuesToBind(exchange).map(bindValues -> {
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 = context.createDataBinder(exchange, null, attributeName);
for (int i = 0; i < paramNames.length; i++) {
Object value = bindValues.get(paramNames[i]);
value = (value != null && value instanceof List ? ((List<?>) value).toArray() : value);
args[i] = binder.convertIfNecessary(value, paramTypes[i], new MethodParameter(ctor, i));
}
return BeanUtils.instantiateClass(ctor, args);
});
}
private boolean hasErrorsArgument(MethodParameter parameter) {
int i = parameter.getParameterIndex();
Class<?>[] paramTypes = parameter.getMethod().getParameterTypes();
return (paramTypes.length > i + 1 && Errors.class.isAssignableFrom(paramTypes[i + 1]));
}
private void validateIfApplicable(WebExchangeDataBinder binder, MethodParameter parameter) {
Annotation[] annotations = parameter.getParameterAnnotations();
for (Annotation ann : annotations) {
Validated validAnnot = AnnotationUtils.getAnnotation(ann, Validated.class);
if (validAnnot != null || ann.annotationType().getSimpleName().startsWith("Valid")) {
Object hints = (validAnnot != null ? validAnnot.value() : AnnotationUtils.getValue(ann));
Object hintArray = (hints instanceof Object[] ? (Object[]) hints : new Object[] {hints});
binder.validate(hintArray);
}
}
}
}