/*
* 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 reactor.core.publisher.Mono;
import org.springframework.core.Conventions;
import org.springframework.core.MethodParameter;
import org.springframework.core.ReactiveAdapter;
import org.springframework.core.ReactiveAdapterRegistry;
import org.springframework.core.ResolvableType;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.reactive.BindingContext;
import org.springframework.web.reactive.result.method.HandlerMethodArgumentResolverSupport;
import org.springframework.web.server.ServerWebExchange;
/**
* Resolve {@link Errors} or {@link BindingResult} method arguments.
* An {@code Errors} argument is expected to appear immediately after the
* model attribute in the method signature.
*
* @author Rossen Stoyanchev
* @since 5.0
*/
public class ErrorsMethodArgumentResolver extends HandlerMethodArgumentResolverSupport {
public ErrorsMethodArgumentResolver(ReactiveAdapterRegistry registry) {
super(registry);
}
@Override
public boolean supportsParameter(MethodParameter parameter) {
return checkParameterTypeNoReactiveWrapper(parameter, Errors.class::isAssignableFrom);
}
@Override
public Mono<Object> resolveArgument(
MethodParameter parameter, BindingContext context, ServerWebExchange exchange) {
String name = getModelAttributeName(parameter);
Object errors = context.getModel().asMap().get(BindingResult.MODEL_KEY_PREFIX + name);
Mono<?> errorsMono;
if (Mono.class.isAssignableFrom(errors.getClass())) {
errorsMono = (Mono<?>) errors;
}
else if (Errors.class.isAssignableFrom(errors.getClass())) {
errorsMono = Mono.just(errors);
}
else {
throw new IllegalStateException(
"Unexpected Errors/BindingResult type: " + errors.getClass().getName());
}
return errorsMono.cast(Object.class);
}
private String getModelAttributeName(MethodParameter parameter) {
Assert.isTrue(parameter.getParameterIndex() > 0,
"Errors argument must be immediately after a model attribute argument");
int index = parameter.getParameterIndex() - 1;
MethodParameter attributeParam = new MethodParameter(parameter.getMethod(), index);
ResolvableType type = ResolvableType.forMethodParameter(attributeParam);
ReactiveAdapter adapter = getAdapterRegistry().getAdapter(type.resolve());
Assert.isNull(adapter, "Errors/BindingResult cannot be used with an async model attribute. " +
"Either declare the model attribute without the async wrapper type " +
"or handle WebExchangeBindException through the async type.");
ModelAttribute annot = parameter.getParameterAnnotation(ModelAttribute.class);
if (annot != null && StringUtils.hasText(annot.value())) {
return annot.value();
}
return Conventions.getVariableNameForParameter(attributeParam);
}
}