org.springframework.web.method.annotation.ModelFactory Maven / Gradle / Ivy
/*
* Copyright 2002-2019 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.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.springframework.beans.BeanUtils;
import org.springframework.core.Conventions;
import org.springframework.core.GenericTypeResolver;
import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.validation.BindingResult;
import org.springframework.web.HttpSessionRequiredException;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.method.support.InvocableHandlerMethod;
import org.springframework.web.method.support.ModelAndViewContainer;
/**
* Assist with initialization of the {@link Model} before controller method
* invocation and with updates to it after the invocation.
*
* On initialization the model is populated with attributes temporarily stored
* in the session and through the invocation of {@code @ModelAttribute} methods.
*
*
On update model attributes are synchronized with the session and also
* {@link BindingResult} attributes are added if missing.
*
* @author Rossen Stoyanchev
* @since 3.1
*/
public final class ModelFactory {
private final List modelMethods = new ArrayList<>();
private final WebDataBinderFactory dataBinderFactory;
private final SessionAttributesHandler sessionAttributesHandler;
/**
* Create a new instance with the given {@code @ModelAttribute} methods.
* @param handlerMethods the {@code @ModelAttribute} methods to invoke
* @param binderFactory for preparation of {@link BindingResult} attributes
* @param attributeHandler for access to session attributes
*/
public ModelFactory(@Nullable List handlerMethods,
WebDataBinderFactory binderFactory, SessionAttributesHandler attributeHandler) {
if (handlerMethods != null) {
for (InvocableHandlerMethod handlerMethod : handlerMethods) {
this.modelMethods.add(new ModelMethod(handlerMethod));
}
}
this.dataBinderFactory = binderFactory;
this.sessionAttributesHandler = attributeHandler;
}
/**
* Populate the model in the following order:
*
* - Retrieve "known" session attributes listed as {@code @SessionAttributes}.
*
- Invoke {@code @ModelAttribute} methods
*
- Find {@code @ModelAttribute} method arguments also listed as
* {@code @SessionAttributes} and ensure they're present in the model raising
* an exception if necessary.
*
* @param request the current request
* @param container a container with the model to be initialized
* @param handlerMethod the method for which the model is initialized
* @throws Exception may arise from {@code @ModelAttribute} methods
*/
public void initModel(NativeWebRequest request, ModelAndViewContainer container, HandlerMethod handlerMethod)
throws Exception {
Map sessionAttributes = this.sessionAttributesHandler.retrieveAttributes(request);
container.mergeAttributes(sessionAttributes);
invokeModelAttributeMethods(request, container);
for (String name : findSessionAttributeArguments(handlerMethod)) {
if (!container.containsAttribute(name)) {
Object value = this.sessionAttributesHandler.retrieveAttribute(request, name);
if (value == null) {
throw new HttpSessionRequiredException("Expected session attribute '" + name + "'", name);
}
container.addAttribute(name, value);
}
}
}
/**
* Invoke model attribute methods to populate the model.
* Attributes are added only if not already present in the model.
*/
private void invokeModelAttributeMethods(NativeWebRequest request, ModelAndViewContainer container)
throws Exception {
while (!this.modelMethods.isEmpty()) {
InvocableHandlerMethod modelMethod = getNextModelMethod(container).getHandlerMethod();
ModelAttribute ann = modelMethod.getMethodAnnotation(ModelAttribute.class);
Assert.state(ann != null, "No ModelAttribute annotation");
if (container.containsAttribute(ann.name())) {
if (!ann.binding()) {
container.setBindingDisabled(ann.name());
}
continue;
}
Object returnValue = modelMethod.invokeForRequest(request, container);
if (!modelMethod.isVoid()){
String returnValueName = getNameForReturnValue(returnValue, modelMethod.getReturnType());
if (!ann.binding()) {
container.setBindingDisabled(returnValueName);
}
if (!container.containsAttribute(returnValueName)) {
container.addAttribute(returnValueName, returnValue);
}
}
}
}
private ModelMethod getNextModelMethod(ModelAndViewContainer container) {
for (ModelMethod modelMethod : this.modelMethods) {
if (modelMethod.checkDependencies(container)) {
this.modelMethods.remove(modelMethod);
return modelMethod;
}
}
ModelMethod modelMethod = this.modelMethods.get(0);
this.modelMethods.remove(modelMethod);
return modelMethod;
}
/**
* Find {@code @ModelAttribute} arguments also listed as {@code @SessionAttributes}.
*/
private List findSessionAttributeArguments(HandlerMethod handlerMethod) {
List result = new ArrayList<>();
for (MethodParameter parameter : handlerMethod.getMethodParameters()) {
if (parameter.hasParameterAnnotation(ModelAttribute.class)) {
String name = getNameForParameter(parameter);
Class paramType = parameter.getParameterType();
if (this.sessionAttributesHandler.isHandlerSessionAttribute(name, paramType)) {
result.add(name);
}
}
}
return result;
}
/**
* Promote model attributes listed as {@code @SessionAttributes} to the session.
* Add {@link BindingResult} attributes where necessary.
* @param request the current request
* @param container contains the model to update
* @throws Exception if creating BindingResult attributes fails
*/
public void updateModel(NativeWebRequest request, ModelAndViewContainer container) throws Exception {
ModelMap defaultModel = container.getDefaultModel();
if (container.getSessionStatus().isComplete()){
this.sessionAttributesHandler.cleanupAttributes(request);
}
else {
this.sessionAttributesHandler.storeAttributes(request, defaultModel);
}
if (!container.isRequestHandled() && container.getModel() == defaultModel) {
updateBindingResult(request, defaultModel);
}
}
/**
* Add {@link BindingResult} attributes to the model for attributes that require it.
*/
private void updateBindingResult(NativeWebRequest request, ModelMap model) throws Exception {
List keyNames = new ArrayList<>(model.keySet());
for (String name : keyNames) {
Object value = model.get(name);
if (value != null && isBindingCandidate(name, value)) {
String bindingResultKey = BindingResult.MODEL_KEY_PREFIX + name;
if (!model.containsAttribute(bindingResultKey)) {
WebDataBinder dataBinder = this.dataBinderFactory.createBinder(request, value, name);
model.put(bindingResultKey, dataBinder.getBindingResult());
}
}
}
}
/**
* Whether the given attribute requires a {@link BindingResult} in the model.
*/
private boolean isBindingCandidate(String attributeName, Object value) {
if (attributeName.startsWith(BindingResult.MODEL_KEY_PREFIX)) {
return false;
}
if (this.sessionAttributesHandler.isHandlerSessionAttribute(attributeName, value.getClass())) {
return true;
}
return (!value.getClass().isArray() && !(value instanceof Collection) &&
!(value instanceof Map) && !BeanUtils.isSimpleValueType(value.getClass()));
}
/**
* Derive the model attribute name for the given method parameter based on
* a {@code @ModelAttribute} parameter annotation (if present) or falling
* back on parameter type based conventions.
* @param parameter a descriptor for the method parameter
* @return the derived name
* @see Conventions#getVariableNameForParameter(MethodParameter)
*/
public static String getNameForParameter(MethodParameter parameter) {
ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
String name = (ann != null ? ann.value() : null);
return (StringUtils.hasText(name) ? name : Conventions.getVariableNameForParameter(parameter));
}
/**
* Derive the model attribute name for the given return value. Results will be
* based on:
*
* - the method {@code ModelAttribute} annotation value
*
- the declared return type if it is more specific than {@code Object}
*
- the actual return value type
*
* @param returnValue the value returned from a method invocation
* @param returnType a descriptor for the return type of the method
* @return the derived name (never {@code null} or empty String)
*/
public static String getNameForReturnValue(@Nullable Object returnValue, MethodParameter returnType) {
ModelAttribute ann = returnType.getMethodAnnotation(ModelAttribute.class);
if (ann != null && StringUtils.hasText(ann.value())) {
return ann.value();
}
else {
Method method = returnType.getMethod();
Assert.state(method != null, "No handler method");
Class containingClass = returnType.getContainingClass();
Class resolvedType = GenericTypeResolver.resolveReturnType(method, containingClass);
return Conventions.getVariableNameForReturnType(method, resolvedType, returnValue);
}
}
private static class ModelMethod {
private final InvocableHandlerMethod handlerMethod;
private final Set dependencies = new HashSet<>();
public ModelMethod(InvocableHandlerMethod handlerMethod) {
this.handlerMethod = handlerMethod;
for (MethodParameter parameter : handlerMethod.getMethodParameters()) {
if (parameter.hasParameterAnnotation(ModelAttribute.class)) {
this.dependencies.add(getNameForParameter(parameter));
}
}
}
public InvocableHandlerMethod getHandlerMethod() {
return this.handlerMethod;
}
public boolean checkDependencies(ModelAndViewContainer mavContainer) {
for (String name : this.dependencies) {
if (!mavContainer.containsAttribute(name)) {
return false;
}
}
return true;
}
@Override
public String toString() {
return this.handlerMethod.getMethod().toGenericString();
}
}
}