DATAREST-1121 - Skip last modified detection for query methods that project.

For an execution of a projecting query method we now skip the last modified detection as it actually doesn't make sense if applied to non-aggregates.

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/HttpHeadersPreparer.java

@@ -73,6 +73,9 @@ public class HttpHeadersPreparer {
 	 */
 	public HttpHeaders prepareHeaders(PersistentEntity<?, ?> entity, Object value) {
 
+		Assert.notNull(entity, "PersistentEntity must not be null!");
+		Assert.notNull(value, "Entity value must not be null!");
+
 		// Add ETag
 		HttpHeaders headers = ETag.from(entity, value).addTo(new HttpHeaders());
 

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/RepositorySearchController.java

@@ -213,6 +213,11 @@ class RepositorySearchController extends AbstractRepositoryRestController {
 
 			PersistentEntity<?, ?> entity = information.getPersistentEntity();
 
+			// Returned value is not of the aggregates type - probably some projection
+			if (!entity.getType().isInstance(it)) {
+				return ResponseEntity.ok(it);
+			}
+
 			return resourceStatus.getStatusAndHeaders(headers, it, entity).toResponseEntity(//
 					() -> assembler.toFullResource(it));
 

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/ResourceStatus.java

@@ -29,6 +29,7 @@ import org.springframework.hateoas.Resource;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.util.Assert;
 
 /**
  * Simple abstraction to capture the status of a resource to determine whether it has been modified or not and produce
@@ -41,6 +42,8 @@ import org.springframework.http.ResponseEntity;
 @RequiredArgsConstructor(staticName = "of")
 class ResourceStatus {
 
+	private static final String INVALID_DOMAIN_OBJECT = "Domain object %s is not an instance of the given PersistentEntity of type %s!";
+
 	private final @NonNull HttpHeadersPreparer preparer;
 
 	/**
@@ -49,12 +52,18 @@ class ResourceStatus {
 	 * 
 	 * @param requestHeaders must not be {@literal null}.
 	 * @param domainObject must not be {@literal null}.
-	 * @param information
+	 * @param entity must not be {@literal null}.
 	 * @return
 	 */
 	public StatusAndHeaders getStatusAndHeaders(HttpHeaders requestHeaders, Object domainObject,
 			PersistentEntity<?, ?> entity) {
 
+		Assert.notNull(requestHeaders, "Request headers must not be null!");
+		Assert.notNull(domainObject, "Domain object must not be null!");
+		Assert.notNull(entity, "PersistentEntity must not be null!");
+		Assert.isTrue(entity.getType().isInstance(domainObject),
+				String.format(INVALID_DOMAIN_OBJECT, domainObject, entity.getType()));
+
 		// Check ETag for If-Non-Match
 
 		List<String> ifNoneMatch = requestHeaders.getIfNoneMatch();
@@ -64,7 +73,8 @@ class ResourceStatus {
 		// Check last modification for If-Modified-Since
 
 		return eTag.matches(entity, domainObject) || preparer.isObjectStillValid(domainObject, requestHeaders)
-				? StatusAndHeaders.notModified(responseHeaders) : StatusAndHeaders.modified(responseHeaders);
+				? StatusAndHeaders.notModified(responseHeaders)
+				: StatusAndHeaders.modified(responseHeaders);
 	}
 
 	@RequiredArgsConstructor(access = AccessLevel.PRIVATE)

spring-data-rest-webmvc/src/test/java/org/springframework/data/rest/webmvc/ResourceStatusUnitTests.java

@@ -21,10 +21,13 @@ import static org.mockito.Mockito.*;
 
 import lombok.Value;
 
+import java.util.Date;
 import java.util.function.Supplier;
 
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.junit.MockitoJUnitRunner;
@@ -49,6 +52,8 @@ public class ResourceStatusUnitTests {
 	@Mock HttpHeadersPreparer preparer;
 	@Mock Supplier<PersistentEntityResource> supplier;
 
+	public @Rule ExpectedException exception = ExpectedException.none();
+
 	@Before
 	public void setUp() {
 
@@ -87,6 +92,15 @@ public class ResourceStatusUnitTests {
 		assertNotModified(status.getStatusAndHeaders(new HttpHeaders(), new Sample(0), entity));
 	}
 
+	@Test // DATAREST-1121
+	public void rejectsInvalidPersistentEntityDomainObjectCombination() {
+
+		exception.expect(IllegalArgumentException.class);
+		exception.expectMessage(entity.getType().getName());
+
+		assertModified(status.getStatusAndHeaders(new HttpHeaders(), new Date(), entity));
+	}
+
 	private void assertModified(StatusAndHeaders statusAndHeaders) {
 
 		assertThat(statusAndHeaders.isModified()).isTrue();