001/*
002 * Copyright 2002-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.validation;
018
019import org.springframework.beans.ConfigurablePropertyAccessor;
020import org.springframework.beans.PropertyAccessorFactory;
021
022/**
023 * Special implementation of the Errors and BindingResult interfaces,
024 * supporting registration and evaluation of binding errors on value objects.
025 * Performs direct field access instead of going through JavaBean getters.
026 *
027 * <p>Since Spring 4.1 this implementation is able to traverse nested fields.
028 *
029 * @author Juergen Hoeller
030 * @since 2.0
031 * @see DataBinder#getBindingResult()
032 * @see DataBinder#initDirectFieldAccess()
033 * @see BeanPropertyBindingResult
034 */
035@SuppressWarnings("serial")
036public class DirectFieldBindingResult extends AbstractPropertyBindingResult {
037
038        private final Object target;
039
040        private final boolean autoGrowNestedPaths;
041
042        private transient ConfigurablePropertyAccessor directFieldAccessor;
043
044
045        /**
046         * Create a new DirectFieldBindingResult instance.
047         * @param target the target object to bind onto
048         * @param objectName the name of the target object
049         */
050        public DirectFieldBindingResult(Object target, String objectName) {
051                this(target, objectName, true);
052        }
053
054        /**
055         * Create a new DirectFieldBindingResult instance.
056         * @param target the target object to bind onto
057         * @param objectName the name of the target object
058         * @param autoGrowNestedPaths whether to "auto-grow" a nested path that contains a null value
059         */
060        public DirectFieldBindingResult(Object target, String objectName, boolean autoGrowNestedPaths) {
061                super(objectName);
062                this.target = target;
063                this.autoGrowNestedPaths = autoGrowNestedPaths;
064        }
065
066
067        @Override
068        public final Object getTarget() {
069                return this.target;
070        }
071
072        /**
073         * Returns the DirectFieldAccessor that this instance uses.
074         * Creates a new one if none existed before.
075         * @see #createDirectFieldAccessor()
076         */
077        @Override
078        public final ConfigurablePropertyAccessor getPropertyAccessor() {
079                if (this.directFieldAccessor == null) {
080                        this.directFieldAccessor = createDirectFieldAccessor();
081                        this.directFieldAccessor.setExtractOldValueForEditor(true);
082                        this.directFieldAccessor.setAutoGrowNestedPaths(this.autoGrowNestedPaths);
083                }
084                return this.directFieldAccessor;
085        }
086
087        /**
088         * Create a new DirectFieldAccessor for the underlying target object.
089         * @see #getTarget()
090         */
091        protected ConfigurablePropertyAccessor createDirectFieldAccessor() {
092                if (this.target == null) {
093                        throw new IllegalStateException("Cannot access fields on null target instance '" + getObjectName() + "'");
094                }
095                return PropertyAccessorFactory.forDirectFieldAccess(this.target);
096        }
097
098}