HHH-19246 Traverse entity graph also for explicit join fetches

hibernate-core/src/main/java/org/hibernate/query/sqm/sql/BaseSqmToSqlAstConverter.java

@@ -7891,6 +7891,15 @@ private Fetch createFetch(FetchParent fetchParent, Fetchable fetchable, Boolean
 			joined = true;
 			alias = fetchedJoin.getExplicitAlias();
 			explicitFetch = true;
+
+			if ( entityGraphTraversalState != null ) {
+				// Still do traverse the entity graph even if we encounter a fetch join
+				traversalResult = entityGraphTraversalState.traverse(
+						fetchParent,
+						fetchable,
+						isKeyFetchable
+				);
+			}
 		}
 		else {
 			fetchablePath = resolvedNavigablePath;

hibernate-core/src/test/java/org/hibernate/orm/test/entitygraph/EntityGraphAndJoinFetchTest.java

@@ -0,0 +1,209 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
+ */
+package org.hibernate.orm.test.entitygraph;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.Id;
+import jakarta.persistence.IdClass;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.NamedAttributeNode;
+import jakarta.persistence.NamedEntityGraph;
+import jakarta.persistence.NamedSubgraph;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.Table;
+import org.hibernate.Hibernate;
+import org.hibernate.jpa.SpecHints;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.io.Serializable;
+import java.math.BigDecimal;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+@DomainModel(
+		annotatedClasses = {
+				EntityGraphAndJoinFetchTest.OrderItem.class,
+				EntityGraphAndJoinFetchTest.Order.class,
+				EntityGraphAndJoinFetchTest.Product.class
+		}
+)
+@SessionFactory
+@JiraKey( value = "HHH-19246")
+public class EntityGraphAndJoinFetchTest {
+
+	private static final Long ORDER_ID = 1l;
+	private static final Long PRODUCT_ID = 2l;
+
+	private static final String NAMED_GRAPH_NAME = "Order.fetchAll";
+	private static final String NAMED_SUBGRAPH_NAME = "OrderItem.fetchAll";
+
+
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					Order order = new Order( ORDER_ID, new BigDecimal( 1000 ) );
+					Product product = new Product( PRODUCT_ID, "laptop" );
+					OrderItem orderItem = new OrderItem( product, order );
+					order.getItems().add( orderItem );
+
+					session.persist( order );
+					session.persist( product );
+					session.persist( orderItem );
+				}
+		);
+	}
+
+	@Test
+	public void testJoinFetchBeingSubsetOfGraph(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					Order order = session.createQuery( "FROM Order e LEFT JOIN FETCH e.items", Order.class )
+							.setHint(
+									SpecHints.HINT_SPEC_LOAD_GRAPH,
+									scope.getSessionFactory().createEntityManager().getEntityGraph( NAMED_GRAPH_NAME )
+							)
+							.getSingleResult();
+					assertTrue( Hibernate.isInitialized( order.getItems() ), "OrderItems have not been fetched" );
+					assertEquals( 1, order.getItems().size(), "OrderItems have not been fetched" );
+					assertTrue( Hibernate.isInitialized( order.getItems().iterator().next().getProduct() ), "Product has not been fetched" );
+				}
+		);
+	}
+
+	@Entity(name = "OrderItem")
+	@IdClass(OrderItem.PK.class)
+	public static class OrderItem {
+
+		@Id
+		@ManyToOne(fetch = FetchType.LAZY)
+		@JoinColumn(name = "product_id")
+		private Product product;
+
+		@Id
+		@ManyToOne(fetch = FetchType.LAZY)
+		@JoinColumn(name = "order_id")
+		private Order order;
+
+		public OrderItem() {
+		}
+
+		public OrderItem(Product product, Order order) {
+			this.product = product;
+			this.order = order;
+		}
+
+		public Product getProduct() {
+			return product;
+		}
+
+		public Order getOrder() {
+			return order;
+		}
+
+		public static class PK implements Serializable {
+			private Long product;
+			private Long order;
+
+			@Override
+			public boolean equals(Object o) {
+				if ( this == o ) {
+					return true;
+				}
+				if ( o == null || getClass() != o.getClass() ) {
+					return false;
+				}
+				PK pk = (PK) o;
+				return Objects.equals( product, pk.product ) && Objects.equals( order, pk.order );
+			}
+
+			@Override
+			public int hashCode() {
+				return Objects.hash( product, order );
+			}
+		}
+	}
+
+
+	@Entity(name = "Order")
+	@Table(name = "ORDER_TABLE")
+	@NamedEntityGraph(
+			name = NAMED_GRAPH_NAME,
+			attributeNodes = {
+					@NamedAttributeNode(value = "items", subgraph = NAMED_SUBGRAPH_NAME)
+			},
+			subgraphs = {
+					@NamedSubgraph(name = NAMED_SUBGRAPH_NAME, attributeNodes = {@NamedAttributeNode("product")})
+			}
+	)
+	public static class Order {
+
+		@Id
+		private Long id;
+
+		private BigDecimal total;
+		@OneToMany(mappedBy = "order")
+		private Set<OrderItem> items = new HashSet<>();
+
+		public Order() {
+		}
+
+		public Order(Long id, BigDecimal total) {
+			this.id = id;
+			this.total = total;
+		}
+
+		public Long getId() {
+			return id;
+		}
+
+		public BigDecimal getTotal() {
+			return total;
+		}
+
+		public Set<OrderItem> getItems() {
+			return items;
+		}
+	}
+
+	@Entity(name = "Product")
+	public static class Product {
+
+		@Id
+		private Long id;
+
+		private String name;
+
+		public Product() {
+		}
+
+		public Product(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public Long getId() {
+			return id;
+		}
+
+		public String getName() {
+			return name;
+		}
+
+	}
+}