Fix for @version field value ignored when updating data.

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

@@ -65,6 +65,7 @@
  * @author Mathias Düsterhöft
  * @author Thomas Mrozinski
  * @author Lars Vierbergen
+ * @author Steve Rutherford
  * @since 2.2
  */
 @SuppressWarnings("NullAway")
@@ -282,7 +283,13 @@ <T> T doMerge(ObjectNode root, T target, ObjectMapper mapper) throws Exception {
 
 			if (!mappedProperties.isWritableField(fieldName)) {
 
-				i.remove();
+				// Allow the version field to pass through so that the underlying store's optimistic locking
+				// mechanism can detect version mismatches (GH-1689). The id field is still stripped to
+				// prevent clients from changing the identity of the resource.
+				PersistentProperty<?> nonWritable = mappedProperties.getPersistentProperty(fieldName);
+				if (nonWritable == null || !nonWritable.isVersionProperty()) {
+					i.remove();
+				}
 				continue;
 			}
 

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

@@ -73,6 +73,7 @@
  * @author Mathias Düsterhöft
  * @author Ken Dombeck
  * @author Thomas Mrozinski
+ * @author Steve Rutherford
  */
 @ExtendWith(MockitoExtension.class)
 class DomainObjectReaderUnitTests {
@@ -208,6 +209,42 @@ void doesNotWipeIdAndVersionPropertyForPut() throws Exception {
 		assertThat(result.version).isEqualTo(1L);
 	}
 
+	@Test // GH-1689
+	void appliesVersionFromClientForPatch() throws Exception {
+
+		VersionedType existing = new VersionedType();
+		existing.id = 1L;
+		existing.version = 1L;
+		existing.firstname = "Dave";
+
+		ObjectMapper mapper = new ObjectMapper();
+		ObjectNode node = (ObjectNode) mapper.readTree("{ \"version\" : 2, \"lastname\" : \"Matthews\" }");
+
+		VersionedType result = reader.doMerge(node, existing, mapper);
+
+		assertThat(result.lastname).isEqualTo("Matthews");
+		assertThat(result.id).isEqualTo(1L);
+		assertThat(result.version).isEqualTo(2L);
+	}
+
+	@Test // GH-1689
+	void doesNotAllowMutatingVersionViaPutBody() throws Exception {
+
+		VersionedType existing = new VersionedType();
+		existing.id = 1L;
+		existing.version = 1L;
+		existing.firstname = "Dave";
+
+		ObjectMapper mapper = new ObjectMapper();
+		ObjectNode node = (ObjectNode) mapper.readTree("{ \"version\" : 9999, \"lastname\" : \"Matthews\" }");
+
+		VersionedType result = reader.readPut(node, existing, mapper);
+
+		assertThat(result.lastname).isEqualTo("Matthews");
+		assertThat(result.id).isEqualTo(1L);
+		assertThat(result.version).isEqualTo(1L);
+	}
+
 	@Test // GH-59
 	void doesNotAllowMutatingIdAndVersionViaPutBody() throws Exception {