DATAJDBC-378 - Proper handling of null and empty collections in JdbcAggregateTemplate.

Original Pull Request: #155

Author: schauder

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

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.jdbc.core;
 
+import java.util.Collections;
 import java.util.Optional;
 
 import org.springframework.context.ApplicationEventPublisher;
@@ -122,6 +123,9 @@ public <T> T save(T instance) {
 	 */
 	@Override
 	public long count(Class<?> domainType) {
+
+		Assert.notNull(domainType, "Domain type must not be null");
+
 		return accessStrategy.count(domainType);
 	}
 
@@ -132,6 +136,9 @@ public long count(Class<?> domainType) {
 	@Override
 	public <T> T findById(Object id, Class<T> domainType) {
 
+		Assert.notNull(id, "Id must not be null");
+		Assert.notNull(domainType, "Domain type must not be null");
+
 		T entity = accessStrategy.findById(id, domainType);
 		if (entity != null) {
 			publishAfterLoad(id, entity);
@@ -145,6 +152,10 @@ public <T> T findById(Object id, Class<T> domainType) {
 	 */
 	@Override
 	public <T> boolean existsById(Object id, Class<T> domainType) {
+
+		Assert.notNull(id, "Id must not be null");
+		Assert.notNull(domainType, "Domain type must not be null");
+
 		return accessStrategy.existsById(id, domainType);
 	}
 
@@ -155,6 +166,8 @@ public <T> boolean existsById(Object id, Class<T> domainType) {
 	@Override
 	public <T> Iterable<T> findAll(Class<T> domainType) {
 
+		Assert.notNull(domainType, "Domain type must not be null");
+
 		Iterable<T> all = accessStrategy.findAll(domainType);
 		publishAfterLoad(all);
 		return all;
@@ -167,6 +180,13 @@ public <T> Iterable<T> findAll(Class<T> domainType) {
 	@Override
 	public <T> Iterable<T> findAllById(Iterable<?> ids, Class<T> domainType) {
 
+		Assert.notNull(ids, "Ids must not be null");
+		Assert.notNull(domainType, "Domain type must not be null");
+
+		if (!ids.iterator().hasNext()) {
+			return Collections.emptyList();
+		}
+
 		Iterable<T> allById = accessStrategy.findAllById(ids, domainType);
 		publishAfterLoad(allById);
 		return allById;
@@ -179,6 +199,9 @@ public <T> Iterable<T> findAllById(Iterable<?> ids, Class<T> domainType) {
 	@Override
 	public <S> void delete(S aggregateRoot, Class<S> domainType) {
 
+		Assert.notNull(aggregateRoot, "Aggregate root must not be null");
+		Assert.notNull(domainType, "Domain type must not be null");
+
 		IdentifierAccessor identifierAccessor = context.getRequiredPersistentEntity(domainType)
 				.getIdentifierAccessor(aggregateRoot);
 
@@ -191,6 +214,10 @@ public <S> void delete(S aggregateRoot, Class<S> domainType) {
 	 */
 	@Override
 	public <S> void deleteById(Object id, Class<S> domainType) {
+
+		Assert.notNull(id, "Id must not be null");
+		Assert.notNull(domainType, "Domain type must not be null");
+
 		deleteTree(id, null, domainType);
 	}
 
@@ -201,6 +228,8 @@ public <S> void deleteById(Object id, Class<S> domainType) {
 	@Override
 	public void deleteAll(Class<?> domainType) {
 
+		Assert.notNull(domainType, "Domain type must not be null");
+
 		AggregateChange<?> change = createDeletingChange(domainType);
 		change.executeWith(interpreter, context, converter);
 	}