Polishing.

Original pull request #1211

Author: schauder

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

@@ -32,13 +32,13 @@
 import org.springframework.data.mapping.IdentifierAccessor;
 import org.springframework.data.mapping.callback.EntityCallbacks;
 import org.springframework.data.relational.core.conversion.AggregateChange;
-import org.springframework.data.relational.core.conversion.RootAggregateChange;
 import org.springframework.data.relational.core.conversion.BatchingAggregateChange;
 import org.springframework.data.relational.core.conversion.MutableAggregateChange;
 import org.springframework.data.relational.core.conversion.RelationalEntityDeleteWriter;
 import org.springframework.data.relational.core.conversion.RelationalEntityInsertWriter;
 import org.springframework.data.relational.core.conversion.RelationalEntityUpdateWriter;
 import org.springframework.data.relational.core.conversion.RelationalEntityVersionUtils;
+import org.springframework.data.relational.core.conversion.RootAggregateChange;
 import org.springframework.data.relational.core.mapping.RelationalMappingContext;
 import org.springframework.data.relational.core.mapping.RelationalPersistentEntity;
 import org.springframework.data.relational.core.mapping.RelationalPersistentProperty;
@@ -294,8 +294,7 @@ private <T> T afterExecute(AggregateChange<T> change, T entityAfterExecution) {
 		return triggerAfterSave(entityAfterExecution, change);
 	}
 
-	private <T> RootAggregateChange<T> beforeExecute(T aggregateRoot,
-													 Function<T, RootAggregateChange<T>> changeCreator) {
+	private <T> RootAggregateChange<T> beforeExecute(T aggregateRoot, Function<T, RootAggregateChange<T>> changeCreator) {
 
 		Assert.notNull(aggregateRoot, "Aggregate instance must not be null!");
 
@@ -337,19 +336,17 @@ private <T> T performSave(T instance, Function<T, RootAggregateChange<T>> change
 
 	private <T> List<T> performSaveAll(Iterable<T> instances) {
 
-		Iterator<T> iterator = instances.iterator();
-		T firstInstance = iterator.next();
+		BatchingAggregateChange<T, RootAggregateChange<T>> batchingAggregateChange = null;
 
-		// noinspection unchecked
-		BatchingAggregateChange<T, RootAggregateChange<T>> batchingAggregateChange = //
-				BatchingAggregateChange.forSave((Class<T>) ClassUtils.getUserClass(firstInstance));
-		batchingAggregateChange.add(beforeExecute(firstInstance, changeCreatorSelectorForSave(firstInstance)));
-
-		while (iterator.hasNext()) {
-			T instance = iterator.next();
+		for (T instance : instances) {
+			if (batchingAggregateChange == null) {
+				batchingAggregateChange = BatchingAggregateChange.forSave((Class<T>) ClassUtils.getUserClass(instance));
+			}
 			batchingAggregateChange.add(beforeExecute(instance, changeCreatorSelectorForSave(instance)));
 		}
 
+		Assert.notNull(batchingAggregateChange, "Iterable in saveAll must not be empty");
+
 		List<T> instancesAfterExecution = executor.executeSave(batchingAggregateChange);
 
 		ArrayList<T> results = new ArrayList<>(instancesAfterExecution.size());
@@ -378,8 +375,7 @@ private <T> RootAggregateChange<T> createUpdateChange(EntityAndPreviousVersion<T
 
 		RootAggregateChange<T> aggregateChange = MutableAggregateChange.forSave(entityAndVersion.entity,
 				entityAndVersion.version);
-		new RelationalEntityUpdateWriter<T>(context).write(entityAndVersion.entity,
-				aggregateChange);
+		new RelationalEntityUpdateWriter<T>(context).write(entityAndVersion.entity, aggregateChange);
 		return aggregateChange;
 	}
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/conversion/DbAction.java

@@ -353,18 +353,29 @@ public String toString() {
 	 * @since 3.0
 	 */
 	abstract class BatchWithValue<T, A extends DbAction<T>, B> implements DbAction<T> {
+
 		private final List<A> actions;
 		private final B batchValue;
 
-		public BatchWithValue(List<A> actions, Function<A, B> batchValueExtractor) {
+		/**
+		 * Creates a {@link BatchWithValue} instance from the given actions and the value which can be extracted by applying #batchValueExtractor on any of the actions.
+		 *
+		 * All actions must result in the same value when #batchValueExtractor is applied.
+		 *
+		 * @param actions the actions forming the batch.
+		 * @param batchValueExtractor function for extracting the {@link #batchValue} from an action.
+		 */
+		BatchWithValue(List<A> actions, Function<A, B> batchValueExtractor) {
+
 			Assert.notEmpty(actions, "Actions must contain at least one action");
+
 			Iterator<A> actionIterator = actions.iterator();
 			this.batchValue = batchValueExtractor.apply(actionIterator.next());
 			actionIterator.forEachRemaining(action -> {
-				if (!batchValueExtractor.apply(action).equals(batchValue)) {
-					throw new IllegalArgumentException("All actions in the batch must have matching batchValue");
-				}
+				Assert.isTrue(batchValueExtractor.apply(action).equals(batchValue),
+						"All actions in the batch must have matching batchValue");
 			});
+
 			this.actions = actions;
 		}
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/conversion/SaveBatchingAggregateChange.java

@@ -49,7 +49,7 @@ public class SaveBatchingAggregateChange<T> implements BatchingAggregateChange<T
 	private final Map<PersistentPropertyPath<RelationalPersistentProperty>, List<DbAction.Delete<?>>> deleteActions = //
 			new HashMap<>();
 
-	public SaveBatchingAggregateChange(Class<T> entityType) {
+	SaveBatchingAggregateChange(Class<T> entityType) {
 		this.entityType = entityType;
 	}