fix #956 problem with getSingleResultOrNull()

Author: gavinking

hibernate-reactive-core/src/main/java/org/hibernate/reactive/session/ReactiveQuery.java

@@ -20,7 +20,6 @@
 
 import javax.persistence.EntityGraph;
 import javax.persistence.NoResultException;
-import javax.persistence.NonUniqueResultException;
 import javax.persistence.Parameter;
 import java.util.List;
 import java.util.concurrent.CompletionStage;
@@ -43,16 +42,7 @@ public interface ReactiveQuery<R> {
 
 	CompletionStage<List<R>> getReactiveResultList();
 
-	default CompletionStage<R> getReactiveSingleResultOrNull() {
-		return getReactiveResultList().thenApply( list -> {
-			switch ( list.size() ) {
-				case 0: return null;
-				case 1: return list.get(0);
-				default: throw new NonUniqueResultException(
-						"query did not return a unique result:  there were " + list.size() + "results" );
-			}
-		} );
-	}
+	CompletionStage<R> getReactiveSingleResultOrNull();
 
 	CompletionStage<Integer> executeReactiveUpdate();
 
@@ -124,6 +114,19 @@ static <R> R extractUniqueResult(List<R> list, AbstractProducedQuery<R> query) {
 		}
 	}
 
+	static <R> R extractUniqueResultOrNull(List<R> list, AbstractProducedQuery<R> query) {
+		try {
+			if ( list.size() == 0 ) {
+				return null;
+			}
+			return AbstractProducedQuery.uniqueElement( list );
+		}
+		catch (HibernateException e) {
+			throw query.getProducer().getExceptionConverter()
+					.convert( e, query.getLockOptions() );
+		}
+	}
+
 	void setPlan(EntityGraph<R> entityGraph);
 
     ReactiveQuery<R> setCacheable(boolean cacheable);

hibernate-reactive-core/src/main/java/org/hibernate/reactive/session/impl/ReactiveNativeQueryImpl.java

@@ -28,6 +28,7 @@
 
 import static org.hibernate.reactive.session.ReactiveQuery.convertQueryException;
 import static org.hibernate.reactive.session.ReactiveQuery.extractUniqueResult;
+import static org.hibernate.reactive.session.ReactiveQuery.extractUniqueResultOrNull;
 
 /**
  *  Implementation of {@link ReactiveNativeQuery} by extension of
@@ -80,6 +81,11 @@ public CompletionStage<R> getReactiveSingleResult() {
 		return getReactiveResultList().thenApply( list -> extractUniqueResult( list, this ) );
 	}
 
+	@Override
+	public CompletionStage<R> getReactiveSingleResultOrNull() {
+		return getReactiveResultList().thenApply( list -> extractUniqueResultOrNull( list, this ) );
+	}
+
 	@Override
 	public CompletionStage<Integer> executeReactiveUpdate() {
 		getProducer().checkTransactionNeededForUpdateOperation( "Executing an update/delete query" );

hibernate-reactive-core/src/main/java/org/hibernate/reactive/session/impl/ReactiveQueryImpl.java

@@ -33,6 +33,7 @@
 import static java.util.Collections.emptyMap;
 import static org.hibernate.reactive.session.ReactiveQuery.convertQueryException;
 import static org.hibernate.reactive.session.ReactiveQuery.extractUniqueResult;
+import static org.hibernate.reactive.session.ReactiveQuery.extractUniqueResultOrNull;
 import static org.hibernate.reactive.util.impl.CompletionStages.completedFuture;
 
 /**
@@ -82,6 +83,14 @@ public CompletionStage<R> getReactiveSingleResult() {
 		return getReactiveResultList().thenApply( list -> extractUniqueResult( list, this ) );
 	}
 
+	@Override
+	public CompletionStage<R> getReactiveSingleResultOrNull() {
+		if ( type!=null && type!=QueryType.SELECT ) {
+			throw new UnsupportedOperationException("not a select query");
+		}
+		return getReactiveResultList().thenApply( list -> extractUniqueResultOrNull( list, this ) );
+	}
+
 	@Override
 	public CompletionStage<Integer> executeReactiveUpdate() {
 		if ( type!=null && type!=QueryType.INSERT_UPDATE_DELETE ) {

hibernate-reactive-core/src/test/java/org/hibernate/reactive/OneToManyTest.java

@@ -55,6 +55,19 @@ public void test(TestContext context) {
                                         .invoke( a -> context.assertEquals( 2, a.books.size() ) )
                                 )
                         )
+                        .chain( () -> getMutinySessionFactory()
+                                .withTransaction( (session, transaction) -> session.createQuery("select a from Author a left join fetch a.books", Author.class )
+                                        .getSingleResultOrNull()
+                                        .invoke( a -> context.assertTrue( Hibernate.isInitialized(a.books) ) )
+                                        .invoke( a -> context.assertEquals( 2, a.books.size() ) )
+                                )
+                        )
+                        .chain( () -> getMutinySessionFactory()
+                                .withTransaction( (session, transaction) -> session.createQuery("select a from Author a left join fetch a.books where 1=0", Author.class )
+                                        .getSingleResultOrNull()
+                                        .invoke(context::assertNull)
+                                )
+                        )
                         .chain( () -> getMutinySessionFactory()
                                 .withTransaction( (session, transaction) -> session.find(Author.class, author.id)
                                         .chain( a -> session.fetch(a.books) )