Return List instead of Iterable in JDBC Repositories and JdbcAggregateOperations.

Closes #1623
Original pull request: #1897

Author: schauder

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

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.jdbc.core;
 
+import java.util.List;
 import java.util.Optional;
 
 import org.springframework.dao.IncorrectUpdateSemanticsDataAccessException;
@@ -58,7 +59,7 @@ public interface JdbcAggregateOperations {
 	 *           resulting update does not update any rows.
 	 * @since 3.0
 	 */
-	<T> Iterable<T> saveAll(Iterable<T> instances);
+	<T> List<T> saveAll(Iterable<T> instances);
 
 	/**
 	 * Dedicated insert function. This skips the test if the aggregate root is new and makes an insert.
@@ -103,7 +104,7 @@ public interface JdbcAggregateOperations {
 	 * @return the saved instances.
 	 * @since 3.1
 	 */
-	<T> Iterable<T> updateAll(Iterable<T> instances);
+	<T> List<T> updateAll(Iterable<T> instances);
 
 	/**
 	 * Counts the number of aggregates of a given type.
@@ -162,7 +163,7 @@ public interface JdbcAggregateOperations {
 	 * @param <T> the type of the aggregate roots. Must not be {@code null}.
 	 * @return Guaranteed to be not {@code null}.
 	 */
-	<T> Iterable<T> findAllById(Iterable<?> ids, Class<T> domainType);
+	<T> List<T> findAllById(Iterable<?> ids, Class<T> domainType);
 
 	/**
 	 * Load all aggregates of a given type.
@@ -171,7 +172,7 @@ public interface JdbcAggregateOperations {
 	 * @param <T> the type of the aggregate roots. Must not be {@code null}.
 	 * @return Guaranteed to be not {@code null}.
 	 */
-	<T> Iterable<T> findAll(Class<T> domainType);
+	<T> List<T> findAll(Class<T> domainType);
 
 	/**
 	 * Load all aggregates of a given type, sorted.
@@ -182,7 +183,7 @@ public interface JdbcAggregateOperations {
 	 * @return Guaranteed to be not {@code null}.
 	 * @since 2.0
 	 */
-	<T> Iterable<T> findAll(Class<T> domainType, Sort sort);
+	<T> List<T> findAll(Class<T> domainType, Sort sort);
 
 	/**
 	 * Load a page of (potentially sorted) aggregates of a given type.
@@ -207,15 +208,15 @@ public interface JdbcAggregateOperations {
 	<T> Optional<T> findOne(Query query, Class<T> domainType);
 
 	/**
-	 * Execute a {@code SELECT} query and convert the resulting items to a {@link Iterable} that is sorted.
+	 * Execute a {@code SELECT} query and convert the resulting items to a {@link List} that is sorted.
 	 *
 	 * @param query must not be {@literal null}.
 	 * @param domainType the entity type must not be {@literal null}.
 	 * @return a non-null sorted list with all the matching results.
 	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one match found.
 	 * @since 3.0
 	 */
-	<T> Iterable<T> findAll(Query query, Class<T> domainType);
+	<T> List<T> findAll(Query query, Class<T> domainType);
 
 	/**
 	 * Returns a {@link Page} of entities matching the given {@link Query}. In case no match could be found, an empty

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

@@ -52,6 +52,7 @@
 import org.springframework.data.relational.core.mapping.event.*;
 import org.springframework.data.relational.core.query.Query;
 import org.springframework.data.support.PageableExecutionUtils;
+import org.springframework.data.util.Streamable;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -171,7 +172,7 @@ public <T> T save(T instance) {
 	}
 
 	@Override
-	public <T> Iterable<T> saveAll(Iterable<T> instances) {
+	public <T> List<T> saveAll(Iterable<T> instances) {
 
 		Assert.notNull(instances, "Aggregate instances must not be null");
 
@@ -204,7 +205,7 @@ public <T> T insert(T instance) {
 	}
 
 	@Override
-	public <T> Iterable<T> insertAll(Iterable<T> instances) {
+	public <T> List<T> insertAll(Iterable<T> instances) {
 
 		Assert.notNull(instances, "Aggregate instances must not be null");
 
@@ -239,7 +240,7 @@ public <T> T update(T instance) {
 	}
 
 	@Override
-	public <T> Iterable<T> updateAll(Iterable<T> instances) {
+	public <T> List<T> updateAll(Iterable<T> instances) {
 
 		Assert.notNull(instances, "Aggregate instances must not be null");
 
@@ -298,7 +299,7 @@ public <T> T findById(Object id, Class<T> domainType) {
 	}
 
 	@Override
-	public <T> Iterable<T> findAll(Class<T> domainType, Sort sort) {
+	public <T> List<T> findAll(Class<T> domainType, Sort sort) {
 
 		Assert.notNull(domainType, "Domain type must not be null");
 
@@ -323,8 +324,13 @@ public <T> Optional<T> findOne(Query query, Class<T> domainType) {
 	}
 
 	@Override
-	public <T> Iterable<T> findAll(Query query, Class<T> domainType) {
-		return accessStrategy.findAll(query, domainType);
+	public <T> List<T> findAll(Query query, Class<T> domainType) {
+
+		Iterable<T> all = accessStrategy.findAll(query, domainType);
+		if (all instanceof List<T> list) {
+			return list;
+		}
+		return Streamable.of(all).toList();
 	}
 
 	@Override
@@ -337,7 +343,7 @@ public <T> Page<T> findAll(Query query, Class<T> domainType, Pageable pageable)
 	}
 
 	@Override
-	public <T> Iterable<T> findAll(Class<T> domainType) {
+	public <T> List<T> findAll(Class<T> domainType) {
 
 		Assert.notNull(domainType, "Domain type must not be null");
 
@@ -346,7 +352,7 @@ public <T> Iterable<T> findAll(Class<T> domainType) {
 	}
 
 	@Override
-	public <T> Iterable<T> findAllById(Iterable<?> ids, Class<T> domainType) {
+	public <T> List<T> findAllById(Iterable<?> ids, Class<T> domainType) {
 
 		Assert.notNull(ids, "Ids must not be null");
 		Assert.notNull(domainType, "Domain type must not be null");
@@ -607,7 +613,7 @@ private MutableAggregateChange<?> createDeletingChange(Class<?> domainType) {
 		return aggregateChange;
 	}
 
-	private <T> Iterable<T> triggerAfterConvert(Iterable<T> all) {
+	private <T> List<T> triggerAfterConvert(Iterable<T> all) {
 
 		List<T> result = new ArrayList<>();
 

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/repository/support/SimpleJdbcRepository.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.jdbc.repository.support;
 
+import java.util.List;
 import java.util.Optional;
 import java.util.function.Function;
 
@@ -30,6 +31,7 @@
 import org.springframework.data.repository.PagingAndSortingRepository;
 import org.springframework.data.repository.query.FluentQuery;
 import org.springframework.data.repository.query.QueryByExampleExecutor;
+import org.springframework.data.util.Streamable;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.util.Assert;
 
@@ -70,7 +72,7 @@ public <S extends T> S save(S instance) {
 
 	@Transactional
 	@Override
-	public <S extends T> Iterable<S> saveAll(Iterable<S> entities) {
+	public <S extends T> List<S> saveAll(Iterable<S> entities) {
 		return entityOperations.saveAll(entities);
 	}
 
@@ -85,12 +87,12 @@ public boolean existsById(ID id) {
 	}
 
 	@Override
-	public Iterable<T> findAll() {
+	public List<T> findAll() {
 		return entityOperations.findAll(entity.getType());
 	}
 
 	@Override
-	public Iterable<T> findAllById(Iterable<ID> ids) {
+	public List<T> findAllById(Iterable<ID> ids) {
 		return entityOperations.findAllById(ids, entity.getType());
 	}
 
@@ -130,7 +132,7 @@ public void deleteAll() {
 	}
 
 	@Override
-	public Iterable<T> findAll(Sort sort) {
+	public List<T> findAll(Sort sort) {
 		return entityOperations.findAll(entity.getType(), sort);
 	}
 
@@ -148,15 +150,15 @@ public <S extends T> Optional<S> findOne(Example<S> example) {
 	}
 
 	@Override
-	public <S extends T> Iterable<S> findAll(Example<S> example) {
+	public <S extends T> List<S> findAll(Example<S> example) {
 
 		Assert.notNull(example, "Example must not be null");
 
 		return findAll(example, Sort.unsorted());
 	}
 
 	@Override
-	public <S extends T> Iterable<S> findAll(Example<S> example, Sort sort) {
+	public <S extends T> List<S> findAll(Example<S> example, Sort sort) {
 
 		Assert.notNull(example, "Example must not be null");
 		Assert.notNull(sort, "Sort must not be null");