autoGrow support in DataBinder for field access

This commit harmonizes the autoGrow feature for both regular bean
property and direct field access.

Issue: SPR-8692

Author: snicoll

spring-context/src/main/java/org/springframework/validation/DataBinder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -246,7 +246,7 @@ public void initBeanPropertyAccess() {
 	public void initDirectFieldAccess() {
 		Assert.state(this.bindingResult == null,
 				"DataBinder is already initialized - call initDirectFieldAccess before other configuration methods");
-		this.bindingResult = new DirectFieldBindingResult(getTarget(), getObjectName());
+		this.bindingResult = new DirectFieldBindingResult(getTarget(), getObjectName(), isAutoGrowNestedPaths());
 		if (this.conversionService != null) {
 			this.bindingResult.initConversion(this.conversionService);
 		}

spring-context/src/main/java/org/springframework/validation/DirectFieldBindingResult.java

@@ -38,6 +38,8 @@ public class DirectFieldBindingResult extends AbstractPropertyBindingResult {
 
 	private final Object target;
 
+	private final boolean autoGrowNestedPaths;
+
 	private transient ConfigurablePropertyAccessor directFieldAccessor;
 
 
@@ -47,8 +49,19 @@ public class DirectFieldBindingResult extends AbstractPropertyBindingResult {
 	 * @param objectName the name of the target object
 	 */
 	public DirectFieldBindingResult(Object target, String objectName) {
+		this(target, objectName, true);
+	}
+
+	/**
+	 * 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(Object target, String objectName, boolean autoGrowNestedPaths) {
 		super(objectName);
 		this.target = target;
+		this.autoGrowNestedPaths = autoGrowNestedPaths;
 	}
 
 
@@ -67,6 +80,7 @@ public final ConfigurablePropertyAccessor getPropertyAccessor() {
 		if (this.directFieldAccessor == null) {
 			this.directFieldAccessor = createDirectFieldAccessor();
 			this.directFieldAccessor.setExtractOldValueForEditor(true);
+			this.directFieldAccessor.setAutoGrowNestedPaths(this.autoGrowNestedPaths);
 		}
 		return this.directFieldAccessor;
 	}

spring-context/src/test/java/org/springframework/tests/sample/beans/FieldAccessBean.java

@@ -28,10 +28,6 @@ public class FieldAccessBean {
 
 	private TestBean spouse;
 
-	public FieldAccessBean() {
-		this.spouse = new TestBean();
-	}
-
 	public String getName() {
 		return name;
 	}

spring-context/src/test/java/org/springframework/validation/DataBinderFieldAccessTests.java

@@ -16,11 +16,16 @@
 
 package org.springframework.validation;
 
+import static org.junit.Assert.*;
+
 import java.beans.PropertyEditorSupport;
 import java.util.Map;
 
-import junit.framework.TestCase;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
+import org.springframework.beans.NullValueInNestedPathException;
 import org.springframework.tests.sample.beans.FieldAccessBean;
 import org.springframework.beans.MutablePropertyValues;
 import org.springframework.beans.NotWritablePropertyException;
@@ -32,9 +37,13 @@
  * @author Stephane Nicoll
  * @since 07.03.2006
  */
-public class DataBinderFieldAccessTests extends TestCase {
+public class DataBinderFieldAccessTests {
+
+	@Rule
+	public final ExpectedException thrown = ExpectedException.none();
 
-	public void testBindingNoErrors() throws Exception {
+	@Test
+	public void bindingNoErrors() throws Exception {
 		FieldAccessBean rod = new FieldAccessBean();
 		DataBinder binder = new DataBinder(rod, "person");
 		assertTrue(binder.isIgnoreUnknownFields());
@@ -56,7 +65,8 @@ public void testBindingNoErrors() throws Exception {
 		assertTrue("Same object", tb.equals(rod));
 	}
 
-	public void testBindingNoErrorsNotIgnoreUnknown() throws Exception {
+	@Test
+	public void bindingNoErrorsNotIgnoreUnknown() throws Exception {
 		FieldAccessBean rod = new FieldAccessBean();
 		DataBinder binder = new DataBinder(rod, "person");
 		binder.initDirectFieldAccess();
@@ -75,7 +85,8 @@ public void testBindingNoErrorsNotIgnoreUnknown() throws Exception {
 		}
 	}
 
-	public void testBindingWithErrors() throws Exception {
+	@Test
+	public void bindingWithErrors() throws Exception {
 		FieldAccessBean rod = new FieldAccessBean();
 		DataBinder binder = new DataBinder(rod, "person");
 		binder.initDirectFieldAccess();
@@ -110,7 +121,8 @@ public void testBindingWithErrors() throws Exception {
 		}
 	}
 
-	public void testedNestedBindingWithDefaultConversionNoErrors() throws Exception {
+	@Test
+	public void nestedBindingWithDefaultConversionNoErrors() throws Exception {
 		FieldAccessBean rod = new FieldAccessBean();
 		DataBinder binder = new DataBinder(rod, "person");
 		assertTrue(binder.isIgnoreUnknownFields());
@@ -126,7 +138,21 @@ public void testedNestedBindingWithDefaultConversionNoErrors() throws Exception
 		assertTrue((rod.getSpouse()).isJedi());
 	}
 
-	public void testBindingWithErrorsAndCustomEditors() throws Exception {
+	@Test
+	public void nestedBindingWithDisabledAutoGrow() throws Exception {
+		FieldAccessBean rod = new FieldAccessBean();
+		DataBinder binder = new DataBinder(rod, "person");
+		binder.setAutoGrowNestedPaths(false);
+		binder.initDirectFieldAccess();
+		MutablePropertyValues pvs = new MutablePropertyValues();
+		pvs.addPropertyValue(new PropertyValue("spouse.name", "Kerry"));
+
+		thrown.expect(NullValueInNestedPathException.class);
+		binder.bind(pvs);
+	}
+
+	@Test
+	public void bindingWithErrorsAndCustomEditors() throws Exception {
 		FieldAccessBean rod = new FieldAccessBean();
 		DataBinder binder = new DataBinder(rod, "person");
 		binder.initDirectFieldAccess();