GH-821 Add support for specifying ORDER BY null handling for supported dialects

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-relational-parent</artifactId>
-	<version>2.4.0-SNAPSHOT</version>
+	<version>2.4.0-821-support-sort-null-handling-SNAPSHOT</version>
 	<packaging>pom</packaging>
 
 	<name>Spring Data Relational Parent</name>

spring-data-jdbc-distribution/pom.xml

@@ -14,7 +14,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-relational-parent</artifactId>
-		<version>2.4.0-SNAPSHOT</version>
+		<version>2.4.0-821-support-sort-null-handling-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-jdbc/pom.xml

@@ -6,7 +6,7 @@
 	<modelVersion>4.0.0</modelVersion>
 
 	<artifactId>spring-data-jdbc</artifactId>
-	<version>2.4.0-SNAPSHOT</version>
+	<version>2.4.0-821-support-sort-null-handling-SNAPSHOT</version>
 
 	<name>Spring Data JDBC</name>
 	<description>Spring Data module for JDBC repositories.</description>
@@ -15,7 +15,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-relational-parent</artifactId>
-		<version>2.4.0-SNAPSHOT</version>
+		<version>2.4.0-821-support-sort-null-handling-SNAPSHOT</version>
 	</parent>
 
 	<properties>

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2021 the original author or authors.
+ * Copyright 2017-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,6 +51,7 @@
  * @author Milan Milanov
  * @author Myeonghyeon Lee
  * @author Mikhail Polivakha
+ * @author Chirag Tailor
  */
 class SqlGenerator {
 
@@ -714,7 +715,7 @@ private OrderByField orderToOrderByField(Sort.Order order) {
 
 		SqlIdentifier columnName = this.entity.getRequiredPersistentProperty(order.getProperty()).getColumnName();
 		Column column = Column.create(columnName, this.getTable());
-		return OrderByField.from(column, order.getDirection());
+		return OrderByField.from(column, order.getDirection()).withNullHandling(order.getNullHandling());
 	}
 
 	/**

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

@@ -257,6 +257,21 @@ void saveAndLoadManyEntitiesWithReferencedEntitySortedAndPaged() {
 				.containsExactly("Star");
 	}
 
+	@Test // GH-821
+	@EnabledOnFeature({SUPPORTS_QUOTED_IDS, SUPPORTS_NULL_HANDLING})
+	void saveAndLoadManyEntitiesWithReferencedEntitySortedWithNullHandling() {
+
+		template.save(createLegoSet(null));
+		template.save(createLegoSet("Star"));
+		template.save(createLegoSet("Frozen"));
+
+		Iterable<LegoSet> reloadedLegoSets = template.findAll(LegoSet.class, Sort.by(new Sort.Order(Sort.Direction.ASC, "name", Sort.NullHandling.NULLS_LAST)));
+
+		assertThat(reloadedLegoSets) //
+				.extracting("name") //
+				.containsExactly("Frozen", "Star", null);
+	}
+
 	@Test // DATAJDBC-112
 	@EnabledOnFeature(SUPPORTS_QUOTED_IDS)
 	void saveAndLoadManyEntitiesByIdWithReferencedEntity() {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2021 the original author or authors.
+ * Copyright 2017-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,7 +25,6 @@
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-
 import org.springframework.data.annotation.Id;
 import org.springframework.data.annotation.ReadOnlyProperty;
 import org.springframework.data.annotation.Version;
@@ -64,6 +63,7 @@
  * @author Milan Milanov
  * @author Myeonghyeon Lee
  * @author Mikhail Polivakha
+ * @author Chirag Tailor
  */
 class SqlGeneratorUnitTests {
 
@@ -245,6 +245,26 @@ void findAllSortedByMultipleFields() {
 				"x_other ASC");
 	}
 
+	@Test // GH-821
+	void findAllSortedWithNullHandling_resolvesNullHandlingWhenDialectSupportsIt() {
+
+		SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class, PostgresDialect.INSTANCE);
+
+		String sql = sqlGenerator.getFindAll(Sort.by(new Sort.Order(Sort.Direction.ASC, "name", Sort.NullHandling.NULLS_LAST)));
+
+		assertThat(sql).contains("ORDER BY \"dummy_entity\".\"x_name\" ASC NULLS LAST");
+	}
+
+	@Test // GH-821
+	void findAllSortedWithNullHandling_ignoresNullHandlingWhenDialectDoesNotSupportIt() {
+
+		SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class, SqlServerDialect.INSTANCE);
+
+		String sql = sqlGenerator.getFindAll(Sort.by(new Sort.Order(Sort.Direction.ASC, "name", Sort.NullHandling.NULLS_LAST)));
+
+		assertThat(sql).endsWith("ORDER BY dummy_entity.x_name ASC");
+	}
+
 	@Test // DATAJDBC-101
 	void findAllPagedByUnpaged() {
 

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/testing/TestDatabaseFeatures.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2021 the original author or authors.
+ * Copyright 2020-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,6 +29,7 @@
  * presence or absence of features in tests.
  *
  * @author Jens Schauder
+ * @author Chirag Tailor
  */
 public class TestDatabaseFeatures {
 
@@ -83,6 +84,10 @@ private void supportsMultiDimensionalArrays() {
 		assumeThat(database).isNotIn(Database.H2, Database.Hsql);
 	}
 
+	private void supportsNullHandling() {
+		assumeThat(database).isNotIn(Database.MySql, Database.MariaDb, Database.SqlServer);
+	}
+
 	public void databaseIs(Database database) {
 		assumeThat(this.database).isEqualTo(database);
 	}
@@ -115,6 +120,7 @@ public enum Feature {
 		SUPPORTS_ARRAYS(TestDatabaseFeatures::supportsArrays), //
 		SUPPORTS_GENERATED_IDS_IN_REFERENCED_ENTITIES(TestDatabaseFeatures::supportsGeneratedIdsInReferencedEntities), //
 		SUPPORTS_NANOSECOND_PRECISION(TestDatabaseFeatures::supportsNanosecondPrecision), //
+		SUPPORTS_NULL_HANDLING(TestDatabaseFeatures::supportsNullHandling),
 		IS_POSTGRES(f -> f.databaseIs(Database.PostgreSql)), //
 		IS_HSQL(f -> f.databaseIs(Database.Hsql));
 

spring-data-relational/pom.xml

@@ -6,15 +6,15 @@
 	<modelVersion>4.0.0</modelVersion>
 
 	<artifactId>spring-data-relational</artifactId>
-	<version>2.4.0-SNAPSHOT</version>
+	<version>2.4.0-821-support-sort-null-handling-SNAPSHOT</version>
 
 	<name>Spring Data Relational</name>
 	<description>Spring Data Relational support</description>
 
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-relational-parent</artifactId>
-		<version>2.4.0-SNAPSHOT</version>
+		<version>2.4.0-821-support-sort-null-handling-SNAPSHOT</version>
 	</parent>
 
 	<properties>

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/AbstractDialect.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2021 the original author or authors.
+ * Copyright 2019-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@
 import java.util.OptionalLong;
 import java.util.function.Function;
 
+import org.springframework.data.domain.Sort;
 import org.springframework.data.relational.core.sql.LockMode;
 import org.springframework.data.relational.core.sql.LockOptions;
 import org.springframework.data.relational.core.sql.Select;
@@ -28,6 +29,7 @@
  *
  * @author Mark Paluch
  * @author Myeonghyeon Lee
+ * @author Chirag Tailor
  * @since 1.1
  */
 public abstract class AbstractDialect implements Dialect {
@@ -42,7 +44,7 @@ public SelectRenderContext getSelectContext() {
 		Function<Select, ? extends CharSequence> afterFromTable = getAfterFromTable();
 		Function<Select, ? extends CharSequence> afterOrderBy = getAfterOrderBy();
 
-		return new DialectSelectRenderContext(afterFromTable, afterOrderBy);
+		return new DialectSelectRenderContext(afterFromTable, afterOrderBy, orderByNullHandling());
 	}
 
 	/**
@@ -105,12 +107,14 @@ static class DialectSelectRenderContext implements SelectRenderContext {
 
 		private final Function<Select, ? extends CharSequence> afterFromTable;
 		private final Function<Select, ? extends CharSequence> afterOrderBy;
+		private final OrderByNullHandling orderByNullHandling;
 
 		DialectSelectRenderContext(Function<Select, ? extends CharSequence> afterFromTable,
-				Function<Select, ? extends CharSequence> afterOrderBy) {
+				Function<Select, ? extends CharSequence> afterOrderBy, OrderByNullHandling orderByNullHandling) {
 
 			this.afterFromTable = afterFromTable;
 			this.afterOrderBy = afterOrderBy;
+			this.orderByNullHandling = orderByNullHandling;
 		}
 
 		/*
@@ -130,6 +134,11 @@ static class DialectSelectRenderContext implements SelectRenderContext {
 		public Function<Select, ? extends CharSequence> afterOrderBy(boolean hasOrderBy) {
 			return afterOrderBy;
 		}
+
+		@Override
+		public String evaluateOrderByNullHandling(Sort.NullHandling nullHandling) {
+			return orderByNullHandling.evaluate(nullHandling);
+		}
 	}
 
 	/**

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/Db2Dialect.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2021 the original author or authors.
+ * Copyright 2020-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@
  * An SQL dialect for DB2.
  *
  * @author Jens Schauder
+ * @author Chirag Tailor
  * @since 2.0
  */
 public class Db2Dialect extends AbstractDialect {

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/Dialect.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2021 the original author or authors.
+ * Copyright 2019-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,6 +33,7 @@
  * @author Myeonghyeon Lee
  * @author Christoph Strobl
  * @author Mikhail Polivakha
+ * @author Chirag Tailor
  * @since 1.1
  */
 public interface Dialect {
@@ -120,4 +121,13 @@ default Set<Class<?>> simpleTypes() {
 	default InsertRenderContext getInsertRenderContext() {
 		return InsertRenderContexts.DEFAULT;
 	}
+
+	/**
+	 * Return the {@link OrderByNullHandling} used by this dialect.
+	 *
+	 * @return the {@link OrderByNullHandling} used by this dialect.
+	 */
+	default OrderByNullHandling orderByNullHandling() {
+		return OrderByNullHandling.SQL_STANDARD;
+	}
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/H2Dialect.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2021 the original author or authors.
+ * Copyright 2019-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,7 @@
  * @author Mark Paluch
  * @author Myeonghyeon Lee
  * @author Christph Strobl
+ * @author Chirag Tailor
  * @since 2.0
  */
 public class H2Dialect extends AbstractDialect {

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/HsqlDbDialect.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2021 the original author or authors.
+ * Copyright 2019-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@
  *
  * @author Jens Schauder
  * @author Myeonghyeon Lee
+ * @author Chirag Tailor
  */
 public class HsqlDbDialect extends AbstractDialect {
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/MySqlDialect.java

@@ -169,4 +169,9 @@ public IdentifierProcessing getIdentifierProcessing() {
 	public Collection<Object> getConverters() {
 		return Collections.singletonList(TimestampAtUtcToOffsetDateTimeConverter.INSTANCE);
 	}
+
+	@Override
+	public OrderByNullHandling orderByNullHandling() {
+		return OrderByNullHandling.NONE;
+	}
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/OracleDialect.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2021 the original author or authors.
+ * Copyright 2019-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,14 +20,14 @@
 import org.springframework.data.convert.WritingConverter;
 
 import java.util.Collection;
-import java.util.Collections;
 
 import static java.util.Arrays.*;
 
 /**
  * An SQL dialect for Oracle.
  *
  * @author Jens Schauder
+ * @author Chirag Tailor
  * @since 2.1
  */
 public class OracleDialect extends AnsiDialect {