/* * 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 * * 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.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 checkParameterType(parameter, Errors.class::isAssignableFrom); } @Override public Mono<Object> resolveArgument( MethodParameter parameter, BindingContext context, ServerWebExchange exchange) { Object errors = getErrors(parameter, context); if (Mono.class.isAssignableFrom(errors.getClass())) { return ((Mono<?>) errors).cast(Object.class); } else if (Errors.class.isAssignableFrom(errors.getClass())) { return Mono.just(errors); } else { throw new IllegalStateException("Unexpected Errors/BindingResult type: " + errors.getClass().getName()); } } private Object getErrors(MethodParameter parameter, BindingContext context) { Assert.isTrue(parameter.getParameterIndex() > 0, "Errors argument must be declared immediately after a model attribute argument"); int index = parameter.getParameterIndex() - 1; MethodParameter attributeParam = MethodParameter.forExecutable(parameter.getExecutable(), index); ReactiveAdapter adapter = getAdapterRegistry().getAdapter(attributeParam.getParameterType()); Assert.state(adapter == null, "An @ModelAttribute and an Errors/BindingResult argument " + "cannot both be declared with an async type wrapper. " + "Either declare the @ModelAttribute without an async wrapper type or " + "handle a WebExchangeBindException error signal through the async type."); ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class); String name = (ann != null && StringUtils.hasText(ann.value()) ? ann.value() : Conventions.getVariableNameForParameter(attributeParam)); Object errors = context.getModel().asMap().get(BindingResult.MODEL_KEY_PREFIX + name); Assert.state(errors != null, () -> "An Errors/BindingResult argument is expected " + "immediately after the @ModelAttribute argument to which it applies. " + "For @RequestBody and @RequestPart arguments, please declare them with a reactive " + "type wrapper and use its onError operators to handle WebExchangeBindException: " + parameter.getMethod()); return errors; } }