DATAJDBC-259 - Polishing.

Unwrap multi-dimensional array types to determine the proper component type. Extend tests. Inline isCollectionOf[Entities|SimpleType]Like calls and remove utility methods on RelationalPersistentProperty as the usage-scope is specific to array handling.

Original pull request: #113.

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

@@ -81,7 +81,7 @@ public class DefaultDataAccessStrategy implements DataAccessStrategy {
 		this.accessStrategy = this;
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#insert(java.lang.Object, java.lang.Class, java.util.Map)
 	 */
@@ -320,7 +320,11 @@ public class DefaultDataAccessStrategy implements DataAccessStrategy {
 			return convertedValue;
 		}
 
-		Class<?> componentType = convertedValue.getClass().getComponentType();
+		Class<?> componentType = convertedValue.getClass();
+		while (componentType.isArray()) {
+			componentType = componentType.getComponentType();
+		}
+
 		String typeName = JDBCType.valueOf(JdbcUtil.sqlTypeFor(componentType)).getName();
 
 		return operations.getJdbcOperations().execute(

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.isCollectionOfEntitiesLike() && id != null) {
+		if (property.isCollectionLike() && property.isEntity() && 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/test/java/org/springframework/data/jdbc/core/JdbcAggregateTemplateIntegrationTests.java

@@ -56,6 +56,7 @@ import org.springframework.transaction.annotation.Transactional;
  *
  * @author Jens Schauder
  * @author Thomas Lang
+ * @author Mark Paluch
  */
 @ContextConfiguration
 @Transactional
@@ -347,6 +348,31 @@ public class JdbcAggregateTemplateIntegrationTests {
 		assertThat(reloaded.digits).isEqualTo(new String[] { "one", "two", "three" });
 	}
 
+	@Test // DATAJDBC-259
+	public void saveAndLoadAnEntityWithMultidimensionalArray() {
+
+		// 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");
+		assumeNot("hsqldb");
+
+		ArrayOwner arrayOwner = new ArrayOwner();
+		arrayOwner.multidimensional = new String[][] { { "one-a", "two-a", "three-a" }, { "one-b", "two-b", "three-b" } };
+
+		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.multidimensional)
+				.isEqualTo(new String[][] { { "one-a", "two-a", "three-a" }, { "one-b", "two-b", "three-b" } });
+	}
+
 	@Test // DATAJDBC-259
 	public void saveAndLoadAnEntityWithList() {
 
@@ -404,6 +430,7 @@ public class JdbcAggregateTemplateIntegrationTests {
 		@Id Long id;
 
 		String[] digits;
+		String[][] multidimensional;
 	}
 
 	@Table("ARRAY_OWNER")

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

@@ -10,4 +10,4 @@ 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);
+CREATE TABLE ARRAY_OWNER (ID BIGINT GENERATED BY DEFAULT AS IDENTITY (START WITH 1) PRIMARY KEY, DIGITS VARCHAR(20) ARRAY[10] NOT NULL, MULTIDIMENSIONAL VARCHAR(20) ARRAY[10] NULL);

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

@@ -13,4 +13,4 @@ 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);
+CREATE TABLE ARRAY_OWNER (ID SERIAL PRIMARY KEY, DIGITS VARCHAR(20)[10], MULTIDIMENSIONAL VARCHAR(20)[10][10]);

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

@@ -60,6 +60,7 @@ public class BasicRelationalPersistentProperty extends AnnotationBasedPersistent
 	private final Lazy<Optional<String>> keyColumnName;
 	private final Lazy<Boolean> isEmbedded;
 	private final Lazy<String> embeddedPrefix;
+	private final Lazy<Class<?>> columnType = Lazy.of(this::doGetColumnType);
 
 	/**
 	 * Creates a new {@link AnnotationBasedPersistentProperty}.
@@ -130,9 +131,12 @@ public class BasicRelationalPersistentProperty extends AnnotationBasedPersistent
 	 *
 	 * @return a {@link Class} that is suitable for usage with JDBC drivers
 	 */
-	@SuppressWarnings("unchecked")
 	@Override
-	public Class getColumnType() {
+	public Class<?> getColumnType() {
+		return columnType.get();
+	}
+
+	private Class<?> doGetColumnType() {
 
 		if (isReference()) {
 			return columnTypeForReference();
@@ -146,7 +150,11 @@ public class BasicRelationalPersistentProperty extends AnnotationBasedPersistent
 
 		Class componentColumnType = columnTypeForNonEntity(getActualType());
 
-		if (isCollectionOfSimpleTypeLike()) {
+		while (componentColumnType.isArray()) {
+			componentColumnType = componentColumnType.getComponentType();
+		}
+
+		if (isCollectionLike() && !isEntity()) {
 			return Array.newInstance(componentColumnType, 0).getClass();
 		}
 

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

@@ -37,9 +37,11 @@ public interface RelationalPersistentProperty extends PersistentProperty<Relatio
 	String getColumnName();
 
 	/**
-	 * The type to be used to store this property in the database.
+	 * The type to be used to store this property in the database. Multidimensional arrays are unwrapped to reflect a
+	 * top-level array type (e.g. {@code String[][]} returns {@code String[]}).
 	 *
 	 * @return a {@link Class} that is suitable for usage with JDBC drivers.
+	 * @see org.springframework.data.jdbc.support.JdbcUtil#sqlTypeFor(Class)
 	 */
 	Class<?> getColumnType();
 
@@ -84,12 +86,4 @@ 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

@@ -134,18 +134,18 @@ public class BasicRelationalPersistentPropertyUnitTests {
 
 		SoftAssertions softly = new SoftAssertions();
 
-		softly.assertThat(listOfString.isCollectionOfSimpleTypeLike())
+		softly.assertThat(listOfString.isCollectionLike() && !listOfString.isEntity())
 				.describedAs("listOfString is a Collection of a simple type.").isEqualTo(true);
-		softly.assertThat(arrayOfString.isCollectionOfSimpleTypeLike())
+		softly.assertThat(arrayOfString.isCollectionLike() && !arrayOfString.isEntity())
 				.describedAs("arrayOfString is a Collection of a simple type.").isTrue();
-		softly.assertThat(listOfEntity.isCollectionOfSimpleTypeLike())
+		softly.assertThat(listOfEntity.isCollectionLike() && !listOfEntity.isEntity())
 				.describedAs("listOfEntity  is a Collection of a simple type.").isFalse();
-		softly.assertThat(arrayOfEntity.isCollectionOfSimpleTypeLike())
+		softly.assertThat(arrayOfEntity.isCollectionLike() && !arrayOfEntity.isEntity())
 				.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());
+				.assertThat(p.isCollectionLike() && !p.isEntity()).describedAs(s + " contains either simple types or entities")
+				.isNotEqualTo(p.isCollectionLike() && p.isEntity());
 
 		checkEitherOr.accept(listOfString,"listOfString");
 		checkEitherOr.accept(arrayOfString,"arrayOfString");