DATAJDBC-286 - Fixes one-to-one relationships for immutable entities.

Original pull request: #99.

Author: maciejwalkowiak

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/EntityRowMapper.java

@@ -38,6 +38,7 @@
  * @author Jens Schauder
  * @author Oliver Gierke
  * @author Mark Paluch
+ * @author Maciej Walkowiak
  */
 public class EntityRowMapper<T> implements RowMapper<T> {
 
@@ -76,7 +77,7 @@ public T mapRow(ResultSet resultSet, int rowNumber) {
 			idValue = readFrom(resultSet, idProperty, prefix);
 		}
 
-		T result = createInstance(entity, resultSet, idValue);
+		T result = createInstance(entity, resultSet, idValue, prefix);
 
 		return entity.requiresPropertyPopulation() //
 				? populateProperties(result, resultSet) //
@@ -97,21 +98,21 @@ private T populateProperties(T result, ResultSet resultSet) {
 				continue;
 			}
 
-			propertyAccessor.setProperty(property, readOrLoadProperty(resultSet, id, property));
+			propertyAccessor.setProperty(property, readOrLoadProperty(resultSet, id, property, ""));
 		}
 
 		return propertyAccessor.getBean();
 	}
 
 	@Nullable
-	private Object readOrLoadProperty(ResultSet resultSet, @Nullable Object id, RelationalPersistentProperty property) {
+	private Object readOrLoadProperty(ResultSet resultSet, @Nullable Object id, RelationalPersistentProperty property, String prefix) {
 
 		if (property.isCollectionLike() && id != null) {
 			return accessStrategy.findAllByProperty(id, property);
 		} else if (property.isMap() && id != null) {
 			return ITERABLE_OF_ENTRY_TO_MAP_CONVERTER.convert(accessStrategy.findAllByProperty(id, property));
 		} else {
-			return readFrom(resultSet, property, "");
+			return readFrom(resultSet, property, prefix);
 		}
 	}
 
@@ -159,7 +160,7 @@ private <S> S readEntityFrom(ResultSet rs, RelationalPersistentProperty property
 			return null;
 		}
 
-		S instance = createInstance(entity, rs, idValue);
+		S instance = createInstance(entity, rs, idValue, prefix);
 
 		PersistentPropertyAccessor<S> accessor = converter.getPropertyAccessor(entity, instance);
 
@@ -180,7 +181,7 @@ private Object getObjectFromResultSet(ResultSet rs, String backreferenceName) {
 		}
 	}
 
-	private <S> S createInstance(RelationalPersistentEntity<S> entity, ResultSet rs, @Nullable Object idValue) {
+	private <S> S createInstance(RelationalPersistentEntity<S> entity, ResultSet rs, @Nullable Object idValue, String prefix) {
 
 		return converter.createInstance(entity, parameter -> {
 
@@ -190,7 +191,7 @@ private <S> S createInstance(RelationalPersistentEntity<S> entity, ResultSet rs,
 
 			RelationalPersistentProperty property = entity.getRequiredPersistentProperty(parameterName);
 
-			return readOrLoadProperty(rs, idValue, property);
+			return readOrLoadProperty(rs, idValue, property, prefix);
 		});
 	}
 }

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/EntityRowMapperUnitTests.java

@@ -58,6 +58,7 @@
  *
  * @author Jens Schauder
  * @author Mark Paluch
+ * @author Maciej Walkowiak
  */
 public class EntityRowMapperUnitTests {
 
@@ -131,6 +132,21 @@ public void simpleOneToOneGetsProperlyExtracted() throws SQLException {
 				.containsExactly(ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha", 24L, "beta");
 	}
 
+	@Test // DATAJDBC-286
+	public void immutableOneToOneGetsProperlyExtracted() throws SQLException {
+
+		ResultSet rs = mockResultSet(asList("id", "name", "child_id", "child_name"), //
+				ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha", 24L, "beta");
+		rs.next();
+
+		OneToOneImmutable extracted = createRowMapper(OneToOneImmutable.class).mapRow(rs, 1);
+
+		assertThat(extracted) //
+				.isNotNull() //
+				.extracting(e -> e.id, e -> e.name, e -> e.child.id, e -> e.child.name) //
+				.containsExactly(ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha", 24L, "beta");
+	}
+
 	@Test // DATAJDBC-113
 	public void collectionReferenceGetsLoadedWithAdditionalSelect() throws SQLException {
 
@@ -371,6 +387,15 @@ static class OneToOne {
 		Trivial child;
 	}
 
+	@RequiredArgsConstructor
+	@Wither
+	static class OneToOneImmutable {
+
+		private final @Id Long id;
+		private final String name;
+		private final TrivialImmutable child;
+	}
+
 	static class OneToSet {
 
 		@Id Long id;