From e325c0152b68120a736e9423524eaccc8b395506 Mon Sep 17 00:00:00 2001
From: Jens Schauder <jschauder@vmware.com>
Date: Tue, 3 Jan 2023 09:34:15 +0100
Subject: [PATCH] Allow empty Iterable arguments in JdbcAggregateTemplate
 again.

This also affects repositories since they delegate to the template.

Closes #1401
---
 .../data/jdbc/core/JdbcAggregateTemplate.java | 24 ++++++++++++++----
 .../core/JdbcAggregateTemplateUnitTests.java  | 25 +++++++++++++++++++
 2 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateTemplate.java b/spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateTemplate.java
index 60c42425..12dff4a4 100644
--- a/spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateTemplate.java
+++ b/spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateTemplate.java
@@ -16,6 +16,7 @@
 package org.springframework.data.jdbc.core;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
@@ -171,7 +172,10 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 	public <T> Iterable<T> saveAll(Iterable<T> instances) {
 
 		Assert.notNull(instances, "Aggregate instances must not be null");
-		Assert.isTrue(instances.iterator().hasNext(), "Aggregate instances must not be empty");
+
+		if (!instances.iterator().hasNext()) {
+			return Collections.emptyList();
+		}
 
 		List<EntityAndChangeCreator<T>> entityAndChangeCreators = new ArrayList<>();
 		for (T instance : instances) {
@@ -200,7 +204,10 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 	public <T> Iterable<T> insertAll(Iterable<T> instances) {
 
 		Assert.notNull(instances, "Aggregate instances must not be null");
-		Assert.isTrue(instances.iterator().hasNext(), "Aggregate instances must not be empty");
+
+		if (!instances.iterator().hasNext()) {
+			return Collections.emptyList();
+		}
 
 		List<EntityAndChangeCreator<T>> entityAndChangeCreators = new ArrayList<>();
 		for (T instance : instances) {
@@ -232,7 +239,10 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 	public <T> Iterable<T> updateAll(Iterable<T> instances) {
 
 		Assert.notNull(instances, "Aggregate instances must not be null");
-		Assert.isTrue(instances.iterator().hasNext(), "Aggregate instances must not be empty");
+
+		if (!instances.iterator().hasNext()) {
+			return Collections.emptyList();
+		}
 
 		List<EntityAndChangeCreator<T>> entityAndChangeCreators = new ArrayList<>();
 		for (T instance : instances) {
@@ -366,7 +376,9 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 	@Override
 	public <T> void deleteAllById(Iterable<?> ids, Class<T> domainType) {
 
-		Assert.isTrue(ids.iterator().hasNext(), "Ids must not be empty");
+		if (!ids.iterator().hasNext()) {
+			return;
+		}
 
 		BatchingAggregateChange<T, DeleteAggregateChange<T>> batchingAggregateChange = BatchingAggregateChange
 				.forDelete(domainType);
@@ -395,7 +407,9 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 	@Override
 	public <T> void deleteAll(Iterable<? extends T> instances) {
 
-		Assert.isTrue(instances.iterator().hasNext(), "Aggregate instances must not be empty");
+		if (!instances.iterator().hasNext()) {
+			return;
+		}
 
 		Map<Class, List<Object>> groupedByType = new HashMap<>();
 
diff --git a/spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/JdbcAggregateTemplateUnitTests.java b/spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/JdbcAggregateTemplateUnitTests.java
index 7d3565f1..2717bacb 100644
--- a/spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/JdbcAggregateTemplateUnitTests.java
+++ b/spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/JdbcAggregateTemplateUnitTests.java
@@ -312,6 +312,31 @@ public class JdbcAggregateTemplateUnitTests {
 		assertThat(all).containsExactly(alfred2, neumann2);
 	}
 
+	@Test // GH-1401
+	public void saveAllWithEmptyListDoesNothing() {
+		assertThat(template.saveAll(emptyList())).isEmpty();
+	}
+
+	@Test // GH-1401
+	public void insertAllWithEmptyListDoesNothing() {
+		assertThat(template.insertAll(emptyList())).isEmpty();
+	}
+
+	@Test // GH-1401
+	public void updateAllWithEmptyListDoesNothing() {
+		assertThat(template.updateAll(emptyList())).isEmpty();
+	}
+
+	@Test // GH-1401
+	public void deleteAllWithEmptyListDoesNothing() {
+		template.deleteAll(emptyList());
+	}
+
+	@Test // GH-1401
+	public void deleteAllByIdWithEmptyListDoesNothing() {
+		template.deleteAllById(emptyList(), SampleEntity.class);
+	}
+
 	@Data
 	@AllArgsConstructor
 	private static class SampleEntity {