/*
 * 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.validation;

import org.springframework.beans.ConfigurablePropertyAccessor;
import org.springframework.beans.PropertyAccessorFactory;
import org.springframework.lang.Nullable;

Special implementation of the Errors and BindingResult interfaces,
supporting registration and evaluation of binding errors on value objects.
Performs direct field access instead of going through JavaBean getters.
Since Spring 4.1 this implementation is able to traverse nested fields.
Author:
Juergen Hoeller
See Also:
DataBinder.getBindingResult()
DataBinder.initDirectFieldAccess()
BeanPropertyBindingResult
Since:
2.0/**
 * Special implementation of the Errors and BindingResult interfaces,
 * supporting registration and evaluation of binding errors on value objects.
 * Performs direct field access instead of going through JavaBean getters.
 *
 * <p>Since Spring 4.1 this implementation is able to traverse nested fields.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @see DataBinder#getBindingResult()
 * @see DataBinder#initDirectFieldAccess()
 * @see BeanPropertyBindingResult
 */
@SuppressWarnings("serial")
public class DirectFieldBindingResult extends AbstractPropertyBindingResult {

	@Nullable
	private final Object target;

	private final boolean autoGrowNestedPaths;

	@Nullable
	private transient ConfigurablePropertyAccessor directFieldAccessor;


	
Create a new DirectFieldBindingResult instance.
Params:
target – the target object to bind onto
objectName – the name of the target object/**
	 * Create a new DirectFieldBindingResult instance.
	 * @param target the target object to bind onto
	 * @param objectName the name of the target object
	 */
	public DirectFieldBindingResult(@Nullable Object target, String objectName) {
		this(target, objectName, true);
	}

	
Create a new DirectFieldBindingResult instance.
Params:
target – the target object to bind onto
objectName – the name of the target object
autoGrowNestedPaths – whether to "auto-grow" a nested path that contains a null value/**
	 * Create a new DirectFieldBindingResult instance.
	 * @param target the target object to bind onto
	 * @param objectName the name of the target object
	 * @param autoGrowNestedPaths whether to "auto-grow" a nested path that contains a null value
	 */
	public DirectFieldBindingResult(@Nullable Object target, String objectName, boolean autoGrowNestedPaths) {
		super(objectName);
		this.target = target;
		this.autoGrowNestedPaths = autoGrowNestedPaths;
	}


	@Override
	@Nullable
	public final Object getTarget() {
		return this.target;
	}

	
Returns the DirectFieldAccessor that this instance uses.
Creates a new one if none existed before.
See Also:
createDirectFieldAccessor()/**
	 * Returns the DirectFieldAccessor that this instance uses.
	 * Creates a new one if none existed before.
	 * @see #createDirectFieldAccessor()
	 */
	@Override
	public final ConfigurablePropertyAccessor getPropertyAccessor() {
		if (this.directFieldAccessor == null) {
			this.directFieldAccessor = createDirectFieldAccessor();
			this.directFieldAccessor.setExtractOldValueForEditor(true);
			this.directFieldAccessor.setAutoGrowNestedPaths(this.autoGrowNestedPaths);
		}
		return this.directFieldAccessor;
	}

	
Create a new DirectFieldAccessor for the underlying target object.
See Also:
getTarget()/**
	 * Create a new DirectFieldAccessor for the underlying target object.
	 * @see #getTarget()
	 */
	protected ConfigurablePropertyAccessor createDirectFieldAccessor() {
		if (this.target == null) {
			throw new IllegalStateException("Cannot access fields on null target instance '" + getObjectName() + "'");
		}
		return PropertyAccessorFactory.forDirectFieldAccess(this.target);
	}

}