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

Original pull request: spring-projects#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;