DATACMNS-596 - Introduced PersistentPropertyAccessor.

To be able to customize the lookup of bean properties by persistent store we now expose a getPropertyAccessor(Object entity) method on PersistentEntity. It returns a PersistentPropertyAccessor which is basically an interface with a simplified API of BeanWrapper.

Reduced the plain BeanWrapper to not perform any type conversion to be able to drop the ConversionService dependency. To compensate for that we introduced a ConvertingPropertyAccessor that takes a ConversionService and delegates to a standard PersistentPropertyAccessor and applies conversions if necessary.

Refactored client APIs to use the PersistentPropertyAccessor instead of referring to BeanWrapper directly. Deprecated BeanWrapper.create(…) for removal in RC1.

src/test/java/org/springframework/data/mapping/model/BasicPersistentEntityUnitTests.java

@@ -37,6 +37,7 @@ import org.springframework.data.annotation.TypeAlias;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentEntitySpec;
 import org.springframework.data.mapping.PersistentProperty;
+import org.springframework.data.mapping.PersistentPropertyAccessor;
 import org.springframework.data.mapping.Person;
 import org.springframework.data.mapping.context.SampleMappingContext;
 import org.springframework.data.mapping.context.SamplePersistentProperty;
@@ -169,6 +170,46 @@ public class BasicPersistentEntityUnitTests<T extends PersistentProperty<T>> {
 		assertThat(entity.getPersistentProperty(CreatedDate.class), is(nullValue()));
 	}
 
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test
+	public void returnsBeanWrapperForPropertyAccessor() {
+
+		SampleMappingContext context = new SampleMappingContext();
+		PersistentEntity<Object, SamplePersistentProperty> entity = context.getPersistentEntity(Entity.class);
+
+		Entity value = new Entity();
+		PersistentPropertyAccessor accessor = entity.getPropertyAccessor(value);
+
+		assertThat(accessor, is(instanceOf(BeanWrapper.class)));
+		assertThat(accessor.getBean(), is((Object) value));
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullBeanForPropertyAccessor() {
+
+		SampleMappingContext context = new SampleMappingContext();
+		PersistentEntity<Object, SamplePersistentProperty> entity = context.getPersistentEntity(Entity.class);
+
+		entity.getPropertyAccessor(null);
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNonMatchingBeanForPropertyAccessor() {
+
+		SampleMappingContext context = new SampleMappingContext();
+		PersistentEntity<Object, SamplePersistentProperty> entity = context.getPersistentEntity(Entity.class);
+
+		entity.getPropertyAccessor("foo");
+	}
+
 	private BasicPersistentEntity<Person, T> createEntity(Comparator<T> comparator) {
 		return new BasicPersistentEntity<Person, T>(ClassTypeInformation.from(Person.class), comparator);
 	}

src/test/java/org/springframework/data/mapping/model/ConvertingPropertyAccessorUnitTests.java

@@ -0,0 +1,149 @@
+/*
+ * Copyright 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.
+ * 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.data.mapping.model;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
+
+import org.junit.Test;
+import org.springframework.core.convert.ConversionService;
+import org.springframework.data.mapping.PersistentPropertyAccessor;
+import org.springframework.data.mapping.context.SampleMappingContext;
+import org.springframework.data.mapping.context.SamplePersistentProperty;
+import org.springframework.format.support.DefaultFormattingConversionService;
+
+/**
+ * Unit tests for {@link ConvertingPropertyAccessor}.
+ * 
+ * @author Oliver Gierke
+ */
+public class ConvertingPropertyAccessorUnitTests {
+
+	static final ConversionService CONVERSION_SERVICE = new DefaultFormattingConversionService();
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullPropertyAccessorDelegate() {
+		new ConvertingPropertyAccessor(null, CONVERSION_SERVICE);
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullConversionService() {
+		new ConvertingPropertyAccessor(new BeanWrapper<Object>(new Object()), null);
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test
+	public void returnsBeanFromDelegate() {
+
+		Object entity = new Entity();
+		assertThat(getAccessor(entity, CONVERSION_SERVICE).getBean(), is(entity));
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test
+	public void convertsPropertyValueToExpectedType() {
+
+		Entity entity = new Entity();
+		entity.id = 1L;
+
+		ConvertingPropertyAccessor accessor = getAccessor(entity, CONVERSION_SERVICE);
+
+		assertThat(accessor.getProperty(getIdProperty(), String.class), is("1"));
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test
+	public void doesNotInvokeConversionForNullValues() {
+
+		ConversionService conversionService = mock(ConversionService.class);
+		ConvertingPropertyAccessor accessor = getAccessor(new Entity(), conversionService);
+
+		assertThat(accessor.getProperty(getIdProperty(), Number.class), is(nullValue()));
+		verify(conversionService, times(0)).convert(1L, Number.class);
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test
+	public void doesNotInvokeConversionIfTypeAlreadyMatches() {
+
+		Entity entity = new Entity();
+		entity.id = 1L;
+
+		ConversionService conversionService = mock(ConversionService.class);
+		ConvertingPropertyAccessor accessor = getAccessor(entity, conversionService);
+
+		assertThat(accessor.getProperty(getIdProperty(), Number.class), is((Number) 1L));
+		verify(conversionService, times(0)).convert(1L, Number.class);
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test
+	public void convertsValueOnSetIfTypesDontMatch() {
+
+		Entity entity = new Entity();
+		ConvertingPropertyAccessor accessor = getAccessor(entity, CONVERSION_SERVICE);
+
+		accessor.setProperty(getIdProperty(), "1");
+
+		assertThat(entity.id, is(1L));
+	}
+
+	/**
+	 * @see DATACMNS-596
+	 */
+	@Test
+	public void doesNotInvokeConversionIfTypeAlreadyMatchesOnSet() {
+
+		ConvertingPropertyAccessor accessor = getAccessor(new Entity(), mock(ConversionService.class));
+
+		accessor.setProperty(getIdProperty(), 1L);
+		verify(mock(ConversionService.class), times(0)).convert(1L, Long.class);
+	}
+
+	private static ConvertingPropertyAccessor getAccessor(Object entity, ConversionService conversionService) {
+
+		PersistentPropertyAccessor wrapper = new BeanWrapper<Object>(entity);
+		return new ConvertingPropertyAccessor(wrapper, conversionService);
+	}
+
+	private static SamplePersistentProperty getIdProperty() {
+
+		SampleMappingContext mappingContext = new SampleMappingContext();
+		BasicPersistentEntity<Object, SamplePersistentProperty> entity = mappingContext.getPersistentEntity(Entity.class);
+		return entity.getPersistentProperty("id");
+	}
+
+	static class Entity {
+		Long id;
+	}
+}