/*
* Copyright 2002-2012 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.method.annotation;
import java.util.ArrayList;
import org.springframework.core.MethodParameter;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
/**
* Resolves {@link Errors} method arguments.
*
* <p>An {@code Errors} method argument is expected to appear immediately after
* the model attribute in the method signature. It is resolved by expecting the
* last two attributes added to the model to be the model attribute and its
* {@link BindingResult}.
*
* @author Rossen Stoyanchev
* @since 3.1
*/
public class ErrorsMethodArgumentResolver implements HandlerMethodArgumentResolver {
public boolean supportsParameter(MethodParameter parameter) {
Class<?> paramType = parameter.getParameterType();
return Errors.class.isAssignableFrom(paramType);
}
public Object resolveArgument(
MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, WebDataBinderFactory binderFactory)
throws Exception {
ModelMap model = mavContainer.getModel();
if (model.size() > 0) {
int lastIndex = model.size()-1;
String lastKey = new ArrayList<String>(model.keySet()).get(lastIndex);
if (lastKey.startsWith(BindingResult.MODEL_KEY_PREFIX)) {
return model.get(lastKey);
}
}
throw new IllegalStateException(
"An Errors/BindingResult argument is expected to be declared immediately after the model attribute, " +
"the @RequestBody or the @RequestPart arguments to which they apply: " + parameter.getMethod());
}
}