DATACMNS-89 - ChainingConverter now eagerly returns values.

The ChainingConverter now returns values as soon as one converter in the chain produces an instance that's compatible to the target type. This allows ResourceProcessor clients to provide a Converter to take care of the complete conversion themselves.

src/test/java/org/springframework/data/repository/query/ResultProcessorUnitTests.java

@@ -28,6 +28,7 @@ import java.util.Map;
 
 import org.junit.Test;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageImpl;
 import org.springframework.data.domain.Pageable;
@@ -61,7 +62,7 @@ public class ResultProcessorUnitTests {
 	@Test
 	public void createsProjectionFromProperties() throws Exception {
 
-		ResultProcessor information = getFactory("findOneProjection");
+		ResultProcessor information = getProcessor("findOneProjection");
 
 		SampleProjection result = information.processResult(Arrays.asList("Matthews"));
 
@@ -75,7 +76,7 @@ public class ResultProcessorUnitTests {
 	@SuppressWarnings("unchecked")
 	public void createsListOfProjectionsFormNestedLists() throws Exception {
 
-		ResultProcessor information = getFactory("findAllProjection");
+		ResultProcessor information = getProcessor("findAllProjection");
 
 		List<String> columns = Arrays.asList("Matthews");
 		List<List<String>> source = new ArrayList<List<String>>(Arrays.asList(columns));
@@ -93,7 +94,7 @@ public class ResultProcessorUnitTests {
 	@SuppressWarnings("unchecked")
 	public void createsListOfProjectionsFromMaps() throws Exception {
 
-		ResultProcessor information = getFactory("findAllProjection");
+		ResultProcessor information = getProcessor("findAllProjection");
 
 		List<Map<String, Object>> source = new ArrayList<Map<String, Object>>(
 				Arrays.asList(Collections.<String, Object> singletonMap("lastname", "Matthews")));
@@ -110,7 +111,7 @@ public class ResultProcessorUnitTests {
 	@Test
 	public void createsListOfProjectionsFromEntity() throws Exception {
 
-		ResultProcessor information = getFactory("findAllProjection");
+		ResultProcessor information = getProcessor("findAllProjection");
 
 		List<Sample> source = new ArrayList<Sample>(Arrays.asList(new Sample("Dave", "Matthews")));
 		List<SampleProjection> result = information.processResult(source);
@@ -125,7 +126,7 @@ public class ResultProcessorUnitTests {
 	@Test
 	public void createsPageOfProjectionsFromEntity() throws Exception {
 
-		ResultProcessor information = getFactory("findPageProjection", Pageable.class);
+		ResultProcessor information = getProcessor("findPageProjection", Pageable.class);
 
 		Page<Sample> source = new PageImpl<Sample>(Arrays.asList(new Sample("Dave", "Matthews")));
 		Page<SampleProjection> result = information.processResult(source);
@@ -140,7 +141,7 @@ public class ResultProcessorUnitTests {
 	@Test
 	public void createsDynamicProjectionFromEntity() throws Exception {
 
-		ResultProcessor information = getFactory("findOneOpenProjection");
+		ResultProcessor information = getProcessor("findOneOpenProjection");
 
 		OpenProjection result = information.processResult(new Sample("Dave", "Matthews"));
 
@@ -156,7 +157,7 @@ public class ResultProcessorUnitTests {
 
 		ParameterAccessor accessor = mock(ParameterAccessor.class);
 
-		ResultProcessor factory = getFactory("findOneDynamic", Class.class);
+		ResultProcessor factory = getProcessor("findOneDynamic", Class.class);
 		assertThat(factory.withDynamicProjection(null), is(factory));
 		assertThat(factory.withDynamicProjection(accessor), is(factory));
 
@@ -166,7 +167,26 @@ public class ResultProcessorUnitTests {
 		assertThat(processor.getReturnedType().getReturnedType(), is(typeCompatibleWith(SampleProjection.class)));
 	}
 
-	private static ResultProcessor getFactory(String methodName, Class<?>... parameters) throws Exception {
+	/**
+	 * @see DATACMNS-89
+	 */
+	@Test
+	public void refrainsFromProjectingIfThePreparingConverterReturnsACompatibleInstance() throws Exception {
+
+		ResultProcessor processor = getProcessor("findAllDtos");
+
+		Object result = processor.processResult(new Sample("Dave", "Matthews"), new Converter<Object, Object>() {
+
+			@Override
+			public Object convert(Object source) {
+				return new SampleDTO();
+			}
+		});
+
+		assertThat(result, is(instanceOf(SampleDTO.class)));
+	}
+
+	private static ResultProcessor getProcessor(String methodName, Class<?>... parameters) throws Exception {
 		return getQueryMethod(methodName, parameters).getResultProcessor();
 	}