DATAJDBC-428 - Fixes BasicJdbcConverter readValue for immutable entity with AggregateReference field.

Original pull request: #172.

Author: mhyeon-lee

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

@@ -57,6 +57,7 @@
  * @author Mark Paluch
  * @author Jens Schauder
  * @author Christoph Strobl
+ * @author Myeonghyeon Lee
  * @since 1.1
  * @see MappingContext
  * @see SimpleTypeHolder
@@ -130,6 +131,9 @@ public Object readValue(@Nullable Object value, TypeInformation<?> type) {
 		}
 
 		if (AggregateReference.class.isAssignableFrom(type.getType())) {
+			if (type.getType().isAssignableFrom(value.getClass())) {
+				return value;
+			}
 
 			return readAggregateReference(value, type);
 		}

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

@@ -51,6 +51,7 @@
 
 import org.springframework.data.annotation.Id;
 import org.springframework.data.annotation.PersistenceConstructor;
+import org.springframework.data.jdbc.core.mapping.AggregateReference;
 import org.springframework.data.jdbc.core.mapping.JdbcMappingContext;
 import org.springframework.data.mapping.PersistentPropertyPath;
 import org.springframework.data.relational.core.mapping.Embedded;
@@ -71,6 +72,7 @@
  * @author Maciej Walkowiak
  * @author Bastian Wilhelm
  * @author Christoph Strobl
+ * @author Myeonghyeon Lee
  */
 public class EntityRowMapperUnitTests {
 
@@ -129,6 +131,21 @@ public void namingStrategyGetsHonoredForConstructor() throws SQLException {
 				.containsExactly(ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha");
 	}
 
+	@Test   // DATAJDBC-427
+	public void simpleWithReferenceGetProperlyExtracted() throws SQLException {
+
+		ResultSet rs = mockResultSet(asList("id", "name", "trivial_id"), //
+			ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha", 100L);
+		rs.next();
+
+		WithReference extracted = createRowMapper(WithReference.class).mapRow(rs, 1);
+
+		assertThat(extracted) //
+			.isNotNull() //
+			.extracting(e -> e.id, e -> e.name, e -> e.trivialId) //
+			.containsExactly(ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha", AggregateReference.to(100L));
+	}
+
 	@Test // DATAJDBC-113
 	public void simpleOneToOneGetsProperlyExtracted() throws SQLException {
 
@@ -159,6 +176,21 @@ public void immutableOneToOneGetsProperlyExtracted() throws SQLException {
 				.containsExactly(ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha", 24L, "beta");
 	}
 
+	@Test   // DATAJDBC-427
+	public void immutableWithReferenceGetsProperlyExtracted() throws SQLException {
+
+		ResultSet rs = mockResultSet(asList("id", "name", "trivial_id"), //
+			ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha", 100L);
+		rs.next();
+
+		WithReferenceImmutable extracted = createRowMapper(WithReferenceImmutable.class).mapRow(rs, 1);
+
+		assertThat(extracted) //
+			.isNotNull() //
+			.extracting(e -> e.id, e -> e.name, e -> e.trivialId) //
+			.containsExactly(ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha", AggregateReference.to(100L));
+	}
+
 	// TODO add additional test for multilevel embeddables
 	@Test // DATAJDBC-111
 	public void simpleEmbeddedGetsProperlyExtracted() throws SQLException {
@@ -440,6 +472,26 @@ static class Trivial {
 		String name;
 	}
 
+	@EqualsAndHashCode
+	@NoArgsConstructor
+	@AllArgsConstructor
+	@Getter
+	static class WithReference {
+
+		@Id Long id;
+		String name;
+		AggregateReference<Trivial, Long> trivialId;
+	}
+
+	@Wither
+	@RequiredArgsConstructor
+	static class WithReferenceImmutable {
+
+		@Id private final Long id;
+		private final String name;
+		private final AggregateReference<TrivialImmutable, Long> trivialId;
+	}
+
 	static class OneToOne {
 
 		@Id Long id;