DATAJDBC-259 - Reading and writing to SQL array types.

Currently works for HsqlDb and Postgres, since the others do not support an array column type.

Original pull request: #113.

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

@@ -18,6 +18,8 @@ package org.springframework.data.jdbc.core;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 
+import java.sql.Connection;
+import java.sql.JDBCType;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -301,13 +303,30 @@ public class DefaultDataAccessStrategy implements DataAccessStrategy {
 			} else {
 
 				Object value = propertyAccessor.getProperty(property);
-				Object convertedValue = converter.writeValue(value, ClassTypeInformation.from(property.getColumnType()));
+				Object convertedValue = convertForWrite(property, value);
+
 				parameters.addValue(prefix + property.getColumnName(), convertedValue, JdbcUtil.sqlTypeFor(property.getColumnType()));
 			}
 		});
 
 		return parameters;
 	}
+	@Nullable
+	private Object convertForWrite(RelationalPersistentProperty property, @Nullable Object value) {
+
+		Object convertedValue = converter.writeValue(value, ClassTypeInformation.from(property.getColumnType()));
+
+		if (convertedValue == null || !convertedValue.getClass().isArray()) {
+			return convertedValue;
+		}
+
+		Class<?> componentType = convertedValue.getClass().getComponentType();
+		String typeName = JDBCType.valueOf(JdbcUtil.sqlTypeFor(componentType)).getName();
+
+		return operations.getJdbcOperations().execute(
+				(Connection c) -> c.createArrayOf(typeName, (Object[]) convertedValue)
+		);
+	}
 
 	@SuppressWarnings("unchecked")
 	@Nullable

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

@@ -110,7 +110,7 @@ public class EntityRowMapper<T> implements RowMapper<T> {
 	private Object readOrLoadProperty(ResultSet resultSet, @Nullable Object id, RelationalPersistentProperty property,
 			String prefix) {
 
-		if (property.isCollectionLike() && id != null) {
+		if (property.isCollectionOfEntitiesLike() && 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));

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

@@ -15,6 +15,9 @@
  */
 package org.springframework.data.jdbc.core.convert;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.core.convert.ConverterNotFoundException;
 import org.springframework.data.convert.CustomConversions;
 import org.springframework.data.jdbc.core.mapping.AggregateReference;
 import org.springframework.data.mapping.context.MappingContext;
@@ -26,6 +29,9 @@ import org.springframework.data.relational.core.mapping.RelationalPersistentProp
 import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
 
+import java.sql.Array;
+import java.sql.SQLException;
+
 /**
  * {@link RelationalConverter} that uses a {@link MappingContext} to apply basic conversion of relational values to
  * property values.
@@ -40,6 +46,8 @@ import org.springframework.lang.Nullable;
  */
 public class BasicJdbcConverter extends BasicRelationalConverter {
 
+	private static final Logger LOG = LoggerFactory.getLogger(BasicJdbcConverter.class);
+
 	/**
 	 * Creates a new {@link BasicRelationalConverter} given {@link MappingContext}.
 	 *
@@ -85,6 +93,14 @@ public class BasicJdbcConverter extends BasicRelationalConverter {
 			return AggregateReference.to(readValue(value, idType));
 		}
 
+		if (value instanceof Array) {
+			try {
+				return readValue(((Array) value).getArray(), type);
+			} catch (SQLException | ConverterNotFoundException e ) {
+				LOG.info("Failed to extract a value of type %s from an Array. Attempting to use standard conversions.", e);
+			}
+		}
+
 		return super.readValue(value, type);
 	}
 

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

@@ -63,6 +63,10 @@ public class JdbcMappingContext extends RelationalMappingContext {
 
 	@Override
 	protected boolean shouldCreatePersistentEntityFor(TypeInformation<?> type) {
-		return super.shouldCreatePersistentEntityFor(type) && !AggregateReference.class.isAssignableFrom(type.getType());
+
+		return super.shouldCreatePersistentEntityFor(type) //
+				&& !AggregateReference.class.isAssignableFrom(type.getType()) //
+				&& !type.isCollectionLike();
 	}
+
 }

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

@@ -21,9 +21,13 @@ import static org.assertj.core.api.Assertions.*;
 import lombok.Data;
 
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import org.assertj.core.api.SoftAssertions;
+import org.junit.Assume;
 import org.junit.ClassRule;
 import org.junit.Rule;
 import org.junit.Test;
@@ -38,8 +42,10 @@ import org.springframework.data.jdbc.testing.TestConfiguration;
 import org.springframework.data.relational.core.conversion.RelationalConverter;
 import org.springframework.data.relational.core.mapping.Column;
 import org.springframework.data.relational.core.mapping.RelationalMappingContext;
+import org.springframework.data.relational.core.mapping.Table;
 import org.springframework.test.annotation.IfProfileValue;
 import org.springframework.test.annotation.ProfileValueSourceConfiguration;
+import org.springframework.test.annotation.ProfileValueUtils;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.rules.SpringClassRule;
 import org.springframework.test.context.junit4.rules.SpringMethodRule;
@@ -318,6 +324,102 @@ public class JdbcAggregateTemplateIntegrationTests {
 		assertThat(reloaded.content).extracting(e -> e.content).containsExactly("content");
 	}
 
+	@Test // DATAJDBC-259
+	public void saveAndLoadAnEntityWithArray() {
+
+		// MySQL and other do not support array datatypes. See
+		// https://dev.mysql.com/doc/refman/8.0/en/data-type-overview.html
+		assumeNot("mysql");
+		assumeNot("mariadb");
+		assumeNot("mssql");
+
+		ArrayOwner arrayOwner = new ArrayOwner();
+		arrayOwner.digits = new String[] { "one", "two", "three" };
+
+		ArrayOwner saved = template.save(arrayOwner);
+
+		assertThat(saved.id).isNotNull();
+
+		ArrayOwner reloaded = template.findById(saved.id, ArrayOwner.class);
+
+		assertThat(reloaded).isNotNull();
+		assertThat(reloaded.id).isEqualTo(saved.id);
+		assertThat(reloaded.digits).isEqualTo(new String[] { "one", "two", "three" });
+	}
+
+	@Test // DATAJDBC-259
+	public void saveAndLoadAnEntityWithList() {
+
+		// MySQL and others do not support array datatypes. See
+		// https://dev.mysql.com/doc/refman/8.0/en/data-type-overview.html
+		assumeNot("mysql");
+		assumeNot("mariadb");
+		assumeNot("mssql");
+
+		ListOwner arrayOwner = new ListOwner();
+		arrayOwner.digits.addAll(Arrays.asList("one", "two", "three"));
+
+		ListOwner saved = template.save(arrayOwner);
+
+		assertThat(saved.id).isNotNull();
+
+		ListOwner reloaded = template.findById(saved.id, ListOwner.class);
+
+		assertThat(reloaded).isNotNull();
+		assertThat(reloaded.id).isEqualTo(saved.id);
+		assertThat(reloaded.digits).isEqualTo(Arrays.asList("one", "two", "three"));
+	}
+
+	@Test // DATAJDBC-259
+	public void saveAndLoadAnEntityWithSet() {
+
+		// MySQL and others do not support array datatypes. See
+		// https://dev.mysql.com/doc/refman/8.0/en/data-type-overview.html
+		assumeNot("mysql");
+		assumeNot("mariadb");
+		assumeNot("mssql");
+
+		SetOwner setOwner = new SetOwner();
+		setOwner.digits.addAll(Arrays.asList("one", "two", "three"));
+
+		SetOwner saved = template.save(setOwner);
+
+		assertThat(saved.id).isNotNull();
+
+		SetOwner reloaded = template.findById(saved.id, SetOwner.class);
+
+		assertThat(reloaded).isNotNull();
+		assertThat(reloaded.id).isEqualTo(saved.id);
+		assertThat(reloaded.digits).isEqualTo(new HashSet<>(Arrays.asList("one", "two", "three")));
+	}
+
+	private static void assumeNot(String dbProfileName) {
+
+		Assume.assumeTrue("true"
+				.equalsIgnoreCase(ProfileValueUtils.retrieveProfileValueSource(JdbcAggregateTemplateIntegrationTests.class)
+						.get("current.database.is.not." + dbProfileName)));
+	}
+
+	private static class ArrayOwner {
+		@Id Long id;
+
+		String[] digits;
+	}
+
+	@Table("ARRAY_OWNER")
+	private static class ListOwner {
+		@Id Long id;
+
+		List<String> digits = new ArrayList<>();
+	}
+
+	@Table("ARRAY_OWNER")
+	private static class SetOwner {
+		@Id Long id;
+
+		Set<String> digits = new HashSet<>();
+	}
+
 	private static LegoSet createLegoSet() {
 
 		LegoSet entity = new LegoSet();
@@ -333,8 +435,7 @@ public class JdbcAggregateTemplateIntegrationTests {
 	@Data
 	static class LegoSet {
 
-		@Column("id1")
-		@Id private Long id;
+		@Column("id1") @Id private Long id;
 
 		private String name;
 
@@ -345,16 +446,14 @@ public class JdbcAggregateTemplateIntegrationTests {
 	@Data
 	static class Manual {
 
-		@Column("id2")
-		@Id private Long id;
+		@Column("id2") @Id private Long id;
 		private String content;
 
 	}
 
 	static class OneToOneParent {
 
-		@Column("id3")
-		@Id private Long id;
+		@Column("id3") @Id private Long id;
 		private String content;
 
 		private ChildNoId child;
@@ -366,8 +465,7 @@ public class JdbcAggregateTemplateIntegrationTests {
 
 	static class ListParent {
 
-		@Column("id4")
-		@Id private Long id;
+		@Column("id4") @Id private Long id;
 		String name;
 		List<ElementNoId> content = new ArrayList<>();
 	}

spring-data-jdbc/src/test/resources/org.springframework.data.jdbc.core/JdbcAggregateTemplateIntegrationTests-hsql.sql

@@ -9,3 +9,5 @@ CREATE TABLE Child_No_Id (ONE_TO_ONE_PARENT INTEGER PRIMARY KEY, content VARCHAR
 
 CREATE TABLE LIST_PARENT ( id4 BIGINT GENERATED BY DEFAULT AS IDENTITY ( START WITH 1 ) PRIMARY KEY, NAME VARCHAR(100));
 CREATE TABLE element_no_id ( content VARCHAR(100), LIST_PARENT_key BIGINT, LIST_PARENT BIGINT);
+
+CREATE TABLE ARRAY_OWNER (ID BIGINT GENERATED BY DEFAULT AS IDENTITY (START WITH 1) PRIMARY KEY, DIGITS VARCHAR(20) ARRAY[10] NOT NULL);

spring-data-jdbc/src/test/resources/org.springframework.data.jdbc.core/JdbcAggregateTemplateIntegrationTests-mariadb.sql

@@ -8,4 +8,4 @@ CREATE TABLE ONE_TO_ONE_PARENT ( id3 BIGINT AUTO_INCREMENT PRIMARY KEY, content
 CREATE TABLE Child_No_Id (ONE_TO_ONE_PARENT INTEGER PRIMARY KEY, content VARCHAR(30));
 
 CREATE TABLE LIST_PARENT ( id4 BIGINT AUTO_INCREMENT PRIMARY KEY, NAME VARCHAR(100));
-CREATE TABLE element_no_id ( content VARCHAR(100), LIST_PARENT_key BIGINT, LIST_PARENT BIGINT);
+CREATE TABLE element_no_id ( content VARCHAR(100), LIST_PARENT_key BIGINT, LIST_PARENT BIGINT);

spring-data-jdbc/src/test/resources/org.springframework.data.jdbc.core/JdbcAggregateTemplateIntegrationTests-mssql.sql

@@ -1,15 +1,15 @@
-DROP TABLE IF EXISTS LEGO_SET;
 DROP TABLE IF EXISTS MANUAL;
+DROP TABLE IF EXISTS LEGO_SET;
 CREATE TABLE LEGO_SET ( id1 BIGINT IDENTITY PRIMARY KEY, NAME VARCHAR(30));
 CREATE TABLE MANUAL ( id2 BIGINT IDENTITY PRIMARY KEY, LEGO_SET BIGINT, ALTERNATIVE BIGINT, CONTENT VARCHAR(2000));
 ALTER TABLE MANUAL ADD FOREIGN KEY (LEGO_SET) REFERENCES LEGO_SET(id1);
 
-DROP TABLE IF EXISTS ONE_TO_ONE_PARENT;
 DROP TABLE IF EXISTS Child_No_Id;
+DROP TABLE IF EXISTS ONE_TO_ONE_PARENT;
 CREATE TABLE ONE_TO_ONE_PARENT ( id3 BIGINT IDENTITY PRIMARY KEY, content VARCHAR(30));
 CREATE TABLE Child_No_Id (ONE_TO_ONE_PARENT BIGINT PRIMARY KEY, content VARCHAR(30));
 
-DROP TABLE IF EXISTS LIST_PARENT;
 DROP TABLE IF EXISTS element_no_id;
+DROP TABLE IF EXISTS LIST_PARENT;
 CREATE TABLE LIST_PARENT ( id4 BIGINT IDENTITY  PRIMARY KEY, NAME VARCHAR(100));
-CREATE TABLE element_no_id ( content VARCHAR(100), LIST_PARENT_key BIGINT, LIST_PARENT BIGINT);
+CREATE TABLE element_no_id ( content VARCHAR(100), LIST_PARENT_key BIGINT, LIST_PARENT BIGINT);

spring-data-jdbc/src/test/resources/org.springframework.data.jdbc.core/JdbcAggregateTemplateIntegrationTests-postgres.sql

@@ -12,3 +12,5 @@ CREATE TABLE Child_No_Id (ONE_TO_ONE_PARENT INTEGER PRIMARY KEY, content VARCHAR
 
 CREATE TABLE LIST_PARENT ( id4 SERIAL PRIMARY KEY, NAME VARCHAR(100));
 CREATE TABLE element_no_id ( content VARCHAR(100), LIST_PARENT_key BIGINT, LIST_PARENT INTEGER);
+
+CREATE TABLE ARRAY_OWNER (ID SERIAL PRIMARY KEY, DIGITS VARCHAR(20) ARRAY[10] NOT NULL);

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/BasicRelationalPersistentProperty.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.relational.core.mapping;
 
+import java.lang.reflect.Array;
 import java.time.ZonedDateTime;
 import java.time.temporal.Temporal;
 import java.util.Date;
@@ -139,7 +140,17 @@ public class BasicRelationalPersistentProperty extends AnnotationBasedPersistent
 
 		Class columnType = columnTypeIfEntity(getActualType());
 
-		return columnType == null ? columnTypeForNonEntity(getActualType()) : columnType;
+		if (columnType != null) {
+			return columnType;
+		}
+
+		Class componentColumnType = columnTypeForNonEntity(getActualType());
+
+		if (isCollectionOfSimpleTypeLike()) {
+			return Array.newInstance(componentColumnType, 0).getClass();
+		}
+
+		return componentColumnType;
 	}
 
 	@Override

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/RelationalPersistentProperty.java

@@ -45,7 +45,7 @@ public interface RelationalPersistentProperty extends PersistentProperty<Relatio
 
 	/**
 	 * The SQL type constant used when using this property as a parameter for a SQL statement.
-	 * 
+	 *
 	 * @return Must not be {@code null}.
 	 * @see java.sql.Types
 	 */
@@ -84,4 +84,12 @@ public interface RelationalPersistentProperty extends PersistentProperty<Relatio
 	default String getEmbeddedPrefix() {
 		return null;
 	};
+
+	default boolean isCollectionOfEntitiesLike() {
+		return isCollectionLike() && isEntity();
+	}
+
+	default boolean isCollectionOfSimpleTypeLike() {
+		return isCollectionLike() && !isEntity();
+	}
 }

spring-data-relational/src/test/java/org/springframework/data/relational/core/mapping/BasicRelationalPersistentPropertyUnitTests.java

@@ -70,12 +70,10 @@ public class BasicRelationalPersistentPropertyUnitTests {
 
 		SoftAssertions softly = new SoftAssertions();
 
-		RelationalPersistentEntity<?> persistentEntity = context.getRequiredPersistentEntity(DummyEntity.class);
-
-		checkTargetType(softly, persistentEntity, "someEnum", String.class);
-		checkTargetType(softly, persistentEntity, "localDateTime", Date.class);
-		checkTargetType(softly, persistentEntity, "zonedDateTime", String.class);
-		checkTargetType(softly, persistentEntity, "uuid", UUID.class);
+		checkTargetType(softly, entity, "someEnum", String.class);
+		checkTargetType(softly, entity, "localDateTime", Date.class);
+		checkTargetType(softly, entity, "zonedDateTime", String.class);
+		checkTargetType(softly, entity, "uuid", UUID.class);
 
 		softly.assertAll();
 	}
@@ -83,8 +81,6 @@ public class BasicRelationalPersistentPropertyUnitTests {
 	@Test // DATAJDBC-106
 	public void detectsAnnotatedColumnName() {
 
-		RelationalPersistentEntity<?> entity = context.getRequiredPersistentEntity(DummyEntity.class);
-
 		assertThat(entity.getRequiredPersistentProperty("name").getColumnName()).isEqualTo("dummy_name");
 		assertThat(entity.getRequiredPersistentProperty("localDateTime").getColumnName())
 				.isEqualTo("dummy_last_updated_at");
@@ -93,9 +89,7 @@ public class BasicRelationalPersistentPropertyUnitTests {
 	@Test // DATAJDBC-218
 	public void detectsAnnotatedColumnAndKeyName() {
 
-		RelationalPersistentProperty listProperty = context //
-				.getRequiredPersistentEntity(DummyEntity.class) //
-				.getRequiredPersistentProperty("someList");
+		RelationalPersistentProperty listProperty = entity.getRequiredPersistentProperty("someList");
 
 		assertThat(listProperty.getReverseColumnName()).isEqualTo("dummy_column_name");
 		assertThat(listProperty.getKeyColumn()).isEqualTo("dummy_key_column_name");
@@ -130,6 +124,40 @@ public class BasicRelationalPersistentPropertyUnitTests {
 		softly.assertAll();
 	}
 
+	@Test // DATAJDBC-259
+	public void classificationOfCollectionLikeProperties() {
+
+		RelationalPersistentProperty listOfString = entity.getRequiredPersistentProperty("listOfString");
+		RelationalPersistentProperty arrayOfString = entity.getRequiredPersistentProperty("arrayOfString");
+		RelationalPersistentProperty listOfEntity = entity.getRequiredPersistentProperty("listOfEntity");
+		RelationalPersistentProperty arrayOfEntity = entity.getRequiredPersistentProperty("arrayOfEntity");
+
+		SoftAssertions softly = new SoftAssertions();
+
+		softly.assertThat(listOfString.isCollectionOfSimpleTypeLike())
+				.describedAs("listOfString is a Collection of a simple type.").isEqualTo(true);
+		softly.assertThat(arrayOfString.isCollectionOfSimpleTypeLike())
+				.describedAs("arrayOfString is a Collection of a simple type.").isTrue();
+		softly.assertThat(listOfEntity.isCollectionOfSimpleTypeLike())
+				.describedAs("listOfEntity  is a Collection of a simple type.").isFalse();
+		softly.assertThat(arrayOfEntity.isCollectionOfSimpleTypeLike())
+				.describedAs("arrayOfEntity is a Collection of a simple type.").isFalse();
+
+		BiConsumer<RelationalPersistentProperty, String> checkEitherOr = (p, s) -> softly
+				.assertThat(p.isCollectionOfSimpleTypeLike()).describedAs(s + " contains either simple types or entities")
+				.isNotEqualTo(p.isCollectionOfEntitiesLike());
+
+		checkEitherOr.accept(listOfString,"listOfString");
+		checkEitherOr.accept(arrayOfString,"arrayOfString");
+		checkEitherOr.accept(listOfEntity,"listOfEntity");
+		checkEitherOr.accept(arrayOfEntity,"arrayOfEntity");
+
+		softly.assertThat(arrayOfString.getColumnType()).isEqualTo(String[].class);
+		softly.assertThat(listOfString.getColumnType()).isEqualTo(String[].class);
+
+		softly.assertAll();
+	}
+
 	private void checkTargetType(SoftAssertions softly, RelationalPersistentEntity<?> persistentEntity,
 			String propertyName, Class<?> expected) {
 
@@ -146,9 +174,14 @@ public class BasicRelationalPersistentPropertyUnitTests {
 		private final SomeEnum someEnum;
 		private final LocalDateTime localDateTime;
 		private final ZonedDateTime zonedDateTime;
-		private final List<String> listField;
 		private final UUID uuid;
 
+		// DATAJDBC-259
+		private final List<String> listOfString;
+		private final String[] arrayOfString;
+		private final List<OtherEntity> listOfEntity;
+		private final OtherEntity[] arrayOfEntity;
+
 		@Column(value = "dummy_column_name", keyColumn = "dummy_key_column_name") private List<Integer> someList;
 
 		// DATACMNS-106
@@ -184,4 +217,7 @@ public class BasicRelationalPersistentPropertyUnitTests {
 	private static class EmbeddableEntity {
 		private final String embeddedTest;
 	}
+
+	@SuppressWarnings("unused")
+	private static class OtherEntity {}
 }

src/main/asciidoc/jdbc.adoc

@@ -118,6 +118,8 @@ The properties of the following types are currently supported:
 
 * `java.util.Date`, `java.time.LocalDate`, `java.time.LocalDateTime`, and `java.time.LocalTime`
 
+* Arrays and Collections of the types mentioned above can be mapped to columns of array type if your database supports that.
+
 * Anything your database driver accepts.
 
 * References to other entities. They are considered a one-to-one relationship, or an embedded type.