HHH-17948 add Session.findAll(), StatelessSession.getAll()

Signed-off-by: Gavin King <gavin@hibernate.org>

hibernate-core/src/main/java/org/hibernate/MultiIdentifierLoadAccess.java

@@ -126,8 +126,8 @@ public interface MultiIdentifierLoadAccess<T> {
 
 	/**
 	 * Should {@link #multiLoad} return entity instances that have been
-	 * {@link Session#remove(Object) marked for removal} in the current
+	 * {@linkplain Session#remove(Object) marked for removal} in the
-	 * session, but not yet {@code delete}d in the database?
+	 * current session, but not yet {@code delete}d in the database?
 	 * <p>
 	 * By default, instances marked for removal are replaced by null in
 	 * the returned list of entities when {@link #enableOrderedReturn}

hibernate-core/src/main/java/org/hibernate/Session.java

@@ -691,6 +691,26 @@ public interface Session extends SharedSessionContract, EntityManager {
 	 */
 	void clear();
 
+	/**
+	 * Return the persistent instances of the given entity class with the given identifiers
+	 * as a list. The position of an instance in the list matches the position of its identifier
+	 * in the given array, and the list contains a null value if there is no persistent instance
+	 * matching a given identifier. If an instance is already associated with the session, that
+	 * instance is returned. This method never returns an uninitialized instance.
+	 * <p>
+	 * Every object returned by {@code findAll()} is either an unproxied instance of the given
+	 * entity class, or a fully-fetched proxy object.
+	 *
+	 * @param entityType the entity type
+	 * @param ids the identifiers
+	 *
+	 * @return an ordered list of persistent instances, with null elements representing missing
+	 *         entities
+	 *
+	 * @since 6.5
+	 */
+	<E> List<E> findAll(Class<E> entityType, Object... ids);
+
 	/**
 	 * Return the persistent instance of the given entity class with the given identifier,
 	 * or null if there is no such persistent instance. If the instance is already associated
@@ -699,8 +719,8 @@ public interface Session extends SharedSessionContract, EntityManager {
 	 * <p>
 	 * This operation is very similar to {@link #find(Class, Object)}.
 	 * <p>
-	 * The object returned by {@code get()} or {@code find() } is either an unproxied instance
+	 * The object returned by {@code get()} or {@code find()} is either an unproxied instance
-	 * of the given entity class, of a fully-fetched proxy object.
+	 * of the given entity class, or a fully-fetched proxy object.
 	 * <p>
 	 * This operation requests {@link LockMode#NONE}, that is, no lock, allowing the object
 	 * to be retrieved from the cache without the cost of database access. However, if it is

hibernate-core/src/main/java/org/hibernate/StatelessSession.java

@@ -9,6 +9,8 @@ package org.hibernate;
 import jakarta.persistence.EntityGraph;
 import org.hibernate.graph.GraphSemantic;
 
+import java.util.List;
+
 /**
  * A command-oriented API often used for performing bulk operations against
  * the database. A stateless session has no persistence context, and always
@@ -250,6 +252,23 @@ public interface StatelessSession extends SharedSessionContract {
 	 */
 	<T> T get(EntityGraph<T> graph, GraphSemantic graphSemantic, Object id, LockMode lockMode);
 
+	/**
+	 * Retrieve multiple rows, returning entity instances in a
+	 * list where the position of an instance in the list matches
+	 * the position of its identifier in the given array, and the
+	 * list contains a null value if there is no persistent
+	 * instance matching a given identifier.
+	 *
+	 * @param entityClass The class of the entity to retrieve
+	 * @param ids The ids of the entities to retrieve
+	 *
+	 * @return an ordered list of detached entity instances, with
+	 *         null elements representing missing entities
+	 *
+	 * @since 6.5
+	 */
+	<T> List<T> getAll(Class<T> entityClass, Object... ids);
+
 	/**
 	 * Refresh the entity instance state from the database.
 	 *

hibernate-core/src/main/java/org/hibernate/engine/spi/SessionDelegatorBaseImpl.java

@@ -953,6 +953,11 @@ public class SessionDelegatorBaseImpl implements SessionImplementor {
 		delegate.detach( entity );
 	}
 
+	@Override
+	public <E> List<E> findAll(Class<E> entityType, Object... ids) {
+		return delegate.findAll( entityType, ids );
+	}
+
 	@Override
 	public <T> T get(Class<T> theClass, Object id) {
 		return delegate.get( theClass, id );

hibernate-core/src/main/java/org/hibernate/engine/spi/SessionLazyDelegator.java

@@ -263,6 +263,11 @@ public class SessionLazyDelegator implements Session {
 		this.lazySession.get().clear();
 	}
 
+	@Override
+	public <E> List<E> findAll(Class<E> entityType, Object... ids) {
+		return this.lazySession.get().findAll( entityType, ids );
+	}
+
 	@Override
 	public <T> T get(Class<T> entityType, Object id) {
 		return this.lazySession.get().get( entityType, id );

hibernate-core/src/main/java/org/hibernate/internal/SessionImpl.java

@@ -19,6 +19,7 @@ import java.sql.Connection;
 import java.sql.NClob;
 import java.sql.SQLException;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.TimeZone;
@@ -946,6 +947,11 @@ public class SessionImpl
 		return this.byId( entityName ).getReference( id );
 	}
 
+	@Override
+	public <E> List<E> findAll(Class<E> entityType, Object... ids) {
+		return this.byMultipleIds( entityType ).multiLoad( ids );
+	}
+
 	@Override
 	public <T> T get(Class<T> entityClass, Object id) throws HibernateException {
 		return this.byId( entityClass ).load( id );

hibernate-core/src/main/java/org/hibernate/internal/StatelessSessionImpl.java

@@ -6,6 +6,9 @@
  */
 package org.hibernate.internal;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
 import java.util.Set;
 import java.util.function.BiConsumer;
 
@@ -60,12 +63,15 @@ import org.hibernate.metamodel.mapping.PluralAttributeMapping;
 import org.hibernate.persister.collection.CollectionPersister;
 import org.hibernate.persister.entity.EntityPersister;
 import org.hibernate.proxy.LazyInitializer;
+import org.hibernate.query.criteria.JpaCriteriaQuery;
+import org.hibernate.query.criteria.JpaRoot;
 import org.hibernate.stat.spi.StatisticsImplementor;
 import org.hibernate.tuple.entity.EntityMetamodel;
 
 import jakarta.persistence.EntityGraph;
 import jakarta.transaction.SystemException;
 
+import static java.util.Arrays.asList;
 import static org.hibernate.engine.internal.ManagedTypeHelper.asPersistentAttributeInterceptable;
 import static org.hibernate.engine.internal.ManagedTypeHelper.isPersistentAttributeInterceptable;
 import static org.hibernate.engine.internal.Versioning.incrementVersion;
@@ -510,6 +516,30 @@ public class StatelessSessionImpl extends AbstractSharedSessionContract implemen
 		}
 	}
 
+	@Override
+	public <T> List<T> getAll(Class<T> entityClass, Object... ids) {
+		for (Object id : ids) {
+			if ( id == null ) {
+				throw new IllegalArgumentException("Null id");
+			}
+		}
+		final EntityPersister persister = getEntityPersister( entityClass.getName() );
+		final JpaCriteriaQuery<T> query = getCriteriaBuilder().createQuery(entityClass);
+		final JpaRoot<T> from = query.from(entityClass);
+		query.where( from.get(persister.getIdentifierPropertyName()).in(ids) );
+		final List<T> resultList = createSelectionQuery(query).getResultList();
+		final List<Object> idList = new ArrayList<>(resultList.size());
+		for (T entity : resultList) {
+			idList.add( persister.getIdentifier(entity, this) );
+		}
+		final List<T> list = new ArrayList<>(ids.length);
+		for (Object id : ids) {
+			final int pos = idList.indexOf(id);
+			list.add( pos < 0 ? null : resultList.get(pos) );
+		}
+		return list;
+	}
+
 	private EntityPersister getEntityPersister(String entityName) {
 		return getFactory().getMappingMetamodel().getEntityDescriptor( entityName );
 	}

hibernate-core/src/test/java/org/hibernate/orm/test/loading/multiLoad/FindAllTest.java

@@ -0,0 +1,43 @@
+package org.hibernate.orm.test.loading.multiLoad;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+@SessionFactory
+@DomainModel(annotatedClasses = FindAllTest.Record.class)
+public class FindAllTest {
+    @Test void test(SessionFactoryScope scope) {
+        scope.inTransaction(s-> {
+            s.persist(new Record(123L,"hello earth"));
+            s.persist(new Record(456L,"hello mars"));
+        });
+        scope.inTransaction(s-> {
+            List<Record> all = s.findAll(Record.class, 456L, 123L, 2L);
+            assertEquals("hello mars",all.get(0).message);
+            assertEquals("hello earth",all.get(1).message);
+            assertNull(all.get(2));
+        });
+    }
+    @Entity
+    static class Record {
+        @Id Long id;
+        String message;
+
+        Record(Long id, String message) {
+            this.id = id;
+            this.message = message;
+        }
+
+        Record() {
+        }
+    }
+}

hibernate-core/src/test/java/org/hibernate/orm/test/stateless/GetAllTest.java

@@ -0,0 +1,43 @@
+package org.hibernate.orm.test.stateless;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+@SessionFactory
+@DomainModel(annotatedClasses = GetAllTest.Record.class)
+public class GetAllTest {
+    @Test void test(SessionFactoryScope scope) {
+        scope.inStatelessTransaction(s-> {
+            s.insert(new Record(123L,"hello earth"));
+            s.insert(new Record(456L,"hello mars"));
+        });
+        scope.inStatelessTransaction(s-> {
+            List<Record> all = s.getAll(Record.class, 456L, 123L, 2L);
+            assertEquals("hello mars",all.get(0).message);
+            assertEquals("hello earth",all.get(1).message);
+            assertNull(all.get(2));
+        });
+    }
+    @Entity
+    static class Record {
+        @Id Long id;
+        String message;
+
+        Record(Long id, String message) {
+            this.id = id;
+            this.message = message;
+        }
+
+        Record() {
+        }
+    }
+}