DATACMNS-842 - Projections on repository methods support Slices now.

ResultProcessor now checks for Slice instead of Page as the projection applying method map(…) is available on Slice as well.

src/main/java/org/springframework/data/repository/query/ResultProcessor.java

@@ -26,7 +26,7 @@ import java.util.Map;
 
 import org.springframework.core.CollectionFactory;
 import org.springframework.core.convert.converter.Converter;
-import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Slice;
 import org.springframework.data.projection.ProjectionFactory;
 import org.springframework.util.Assert;
 
@@ -129,8 +129,8 @@ public class ResultProcessor {
 
 		ChainingConverter converter = ChainingConverter.of(type.getReturnedType(), preparingConverter).and(this.converter);
 
-		if (source instanceof Page && method.isPageQuery()) {
-			return (T) ((Page<?>) source).map(converter);
+		if (source instanceof Slice && method.isPageQuery() || method.isSliceQuery()) {
+			return (T) ((Slice<?>) source).map(converter);
 		}
 
 		if (source instanceof Collection && method.isCollectionQuery()) {

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

@@ -32,6 +32,8 @@ 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;
+import org.springframework.data.domain.Slice;
+import org.springframework.data.domain.SliceImpl;
 import org.springframework.data.projection.SpelAwareProxyProjectionFactory;
 import org.springframework.data.repository.Repository;
 import org.springframework.data.repository.core.support.DefaultRepositoryMetadata;
@@ -196,6 +198,23 @@ public class ResultProcessorUnitTests {
 		assertThat(getProcessor("findOneDto").processResult(null), is(nullValue()));
 	}
 
+	/**
+	 * @see DATACMNS-842
+	 */
+	@Test
+	public void supportsSlicesAsReturnWrapper() throws Exception {
+
+		Slice<Sample> slice = new SliceImpl<Sample>(Collections.singletonList(new Sample("Dave", "Matthews")));
+
+		Object result = getProcessor("findSliceProjection", Pageable.class).processResult(slice);
+
+		assertThat(result, is(instanceOf(Slice.class)));
+
+		List<?> content = ((Slice<?>) result).getContent();
+		assertThat(content, is(not(empty())));
+		assertThat(content.get(0), is(instanceOf(SampleProjection.class)));
+	}
+
 	private static ResultProcessor getProcessor(String methodName, Class<?>... parameters) throws Exception {
 		return getQueryMethod(methodName, parameters).getResultProcessor();
 	}
@@ -225,6 +244,8 @@ public class ResultProcessorUnitTests {
 
 		Page<SampleProjection> findPageProjection(Pageable pageable);
 
+		Slice<SampleProjection> findSliceProjection(Pageable pageable);
+
 		<T> T findOneDynamic(Class<T> type);
 	}