DATAJDBC-341 - Map NULL values in EntityRowMapper for columns not being fetched in the query.

Original pull request: #170.

Author: THD-Thomas-Lang

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

@@ -59,10 +59,10 @@
  * @author Jens Schauder
  * @author Christoph Strobl
  * @author Myeonghyeon Lee
- * @since 1.1
  * @see MappingContext
  * @see SimpleTypeHolder
  * @see CustomConversions
+ * @since 1.1
  */
 public class BasicJdbcConverter extends BasicRelationalConverter implements JdbcConverter {
 
@@ -401,7 +401,35 @@ private T populateProperties(T instance, @Nullable Object idValue) {
 					continue;
 				}
 
-				propertyAccessor.setProperty(property, readOrLoadProperty(idValue, property));
+				// check if property is in the result set
+				// if not - leave it out
+				// DATAJDBC-341
+				if (property.isEntity() || property.isEmbedded()) {
+					propertyAccessor.setProperty(property, readOrLoadProperty(idValue, property));
+				} else {
+					try {
+						if (resultSet.findColumn(property.getColumnName().getReference(identifierProcessing)) > 0) {
+							propertyAccessor.setProperty(property, readOrLoadProperty(idValue, property));
+						} else {
+							try {
+								propertyAccessor.setProperty(property, readOrLoadProperty(idValue, property));
+							} catch (Exception exception) {
+								LOG.info(
+										"The result set is not corresponding to the target entity. Left out properties will be set to standard values (NULL for reference types, 0 for primitives.");
+							}
+						}
+					} catch (SQLException e) {
+						String columnAlias = path.extendBy(property).getColumnAlias().getReference(identifierProcessing);
+						try {
+							if (resultSet.findColumn(columnAlias) > 0) {
+								propertyAccessor.setProperty(property, readOrLoadProperty(idValue, property));
+							}
+						} catch (SQLException ex) {
+							LOG.info(String.format("Cannot find column named %s within the result set!", property.getColumnName()));
+						}
+					}
+				}
+
 			}
 
 			return propertyAccessor.getBean();
@@ -523,7 +551,8 @@ private Object getObjectFromResultSet(String backreferenceName) {
 			try {
 				return resultSet.getObject(backreferenceName);
 			} catch (SQLException o_O) {
-				throw new MappingException(String.format("Could not read value %s from result set!", backreferenceName), o_O);
+				LOG.info(String.format("Could not read value %s from result set! Use null as value.", backreferenceName), o_O);
+				return null;
 			}
 		}
 

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

@@ -32,11 +32,7 @@
 
 import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -87,6 +83,35 @@ public String getColumnName(RelationalPersistentProperty property) {
 		}
 	};
 
+	@Test // DATAJDBC-341
+	public void mapNotNeededValueTypePropertiesToNull() throws SQLException {
+		ResultSet rs = mockResultSet(singletonList("id"), //
+				ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha");
+		rs.next();
+		Trivial extracted = createRowMapper(Trivial.class).mapRow(rs, 1);
+
+		assertThat(extracted) //
+				.isNotNull() //
+				.extracting(e -> e.id, e -> e.name) //
+				.containsExactly(ID_FOR_ENTITY_NOT_REFERENCING_MAP, null);
+
+	}
+
+	@Test // DATAJDBC-341
+	public void mapNotNeededPrimitiveTypePropertiesToNull() throws SQLException {
+		ResultSet rs = mockResultSet(singletonList("id"), //
+				ID_FOR_ENTITY_NOT_REFERENCING_MAP, "alpha");
+		rs.next();
+		TrivialMapPropertiesToNullIfNotNeeded extracted = createRowMapper(TrivialMapPropertiesToNullIfNotNeeded.class)
+				.mapRow(rs, 1);
+
+		assertThat(extracted) //
+				.isNotNull() //
+				.extracting(e -> e.id, e -> e.age) //
+				.containsExactly(ID_FOR_ENTITY_NOT_REFERENCING_MAP, 0);
+
+	}
+
 	@Test // DATAJDBC-113
 	public void simpleEntitiesGetProperlyExtracted() throws SQLException {
 
@@ -477,6 +502,19 @@ static class Trivial {
 		String name;
 	}
 
+	@EqualsAndHashCode
+	@NoArgsConstructor
+	@AllArgsConstructor
+	@Getter
+	static class TrivialMapPropertiesToNullIfNotNeeded {
+
+		@Id Long id;
+		int age;
+		String phone;
+		Boolean isSupreme;
+		long referenceToCustomer;
+	}
+
 	@EqualsAndHashCode
 	@NoArgsConstructor
 	@AllArgsConstructor
@@ -762,11 +800,18 @@ public Object answer(InvocationOnMock invocation) throws Throwable {
 					return isAfterLast() || isBeforeFirst() ? 0 : index + 1;
 				case "toString":
 					return this.toString();
+				case "findColumn":
+					return isThereAColumnNamed(invocation.getArgument(0));
 				default:
 					throw new OperationNotSupportedException(invocation.getMethod().getName());
 			}
 		}
 
+		private int isThereAColumnNamed(String name) {
+			Optional<Map<String, Object>> first = values.stream().filter(s -> s.equals(name)).findFirst();
+			return (first.isPresent()) ? 1 : 0;
+		}
+
 		private boolean isAfterLast() {
 			return index >= values.size() && !values.isEmpty();
 		}