From a36393b93fe845589fa5584552cb72e2d3845e33 Mon Sep 17 00:00:00 2001
From: Christian Beikov <christian.beikov@gmail.com>
Date: Tue, 23 Jan 2024 18:45:58 +0100
Subject: [PATCH] HHH-17670 Test and fix for NPE in FromClause#findTableGroup

---
 .../sql/ast/tree/from/FromClause.java         |   2 +-
 .../batch/BatchSubselectCollection3Test.java  | 112 ++++++++++++++++++
 2 files changed, 113 insertions(+), 1 deletion(-)
 create mode 100644 hibernate-core/src/test/java/org/hibernate/orm/test/batch/BatchSubselectCollection3Test.java

diff --git a/hibernate-core/src/main/java/org/hibernate/sql/ast/tree/from/FromClause.java b/hibernate-core/src/main/java/org/hibernate/sql/ast/tree/from/FromClause.java
index 74d3974de0..ffeb9e26c8 100644
--- a/hibernate-core/src/main/java/org/hibernate/sql/ast/tree/from/FromClause.java
+++ b/hibernate-core/src/main/java/org/hibernate/sql/ast/tree/from/FromClause.java
@@ -232,7 +232,7 @@ public class FromClause implements SqlAstNode {
 					if ( navigablePath.equals( tg.getNavigablePath() ) ) {
 						return tg;
 					}
-					if ( tg instanceof OneToManyTableGroup && navigablePath.getParent().equals( tg.getNavigablePath() ) ) {
+					if ( tg instanceof OneToManyTableGroup && tg.getNavigablePath().equals( navigablePath.getParent() ) ) {
 						return ( (OneToManyTableGroup) tg ).getTableGroup( CollectionPart.Nature.fromName( navigablePath.getLocalName() ) );
 					}
 					return null;
diff --git a/hibernate-core/src/test/java/org/hibernate/orm/test/batch/BatchSubselectCollection3Test.java b/hibernate-core/src/test/java/org/hibernate/orm/test/batch/BatchSubselectCollection3Test.java
new file mode 100644
index 0000000000..397cda4881
--- /dev/null
+++ b/hibernate-core/src/test/java/org/hibernate/orm/test/batch/BatchSubselectCollection3Test.java
@@ -0,0 +1,112 @@
+package org.hibernate.orm.test.batch;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.hibernate.annotations.Fetch;
+import org.hibernate.annotations.FetchMode;
+import org.hibernate.cfg.AvailableSettings;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.ServiceRegistry;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.hibernate.testing.orm.junit.Setting;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.OneToMany;
+
+@DomainModel(
+		annotatedClasses = {
+				BatchSubselectCollection3Test.SimpleA.class,
+				BatchSubselectCollection3Test.SimpleB.class,
+				BatchSubselectCollection3Test.SimpleC.class,
+				BatchSubselectCollection3Test.SimpleD.class
+		}
+)
+@SessionFactory
+@ServiceRegistry(
+		settings = {
+				@Setting(name = AvailableSettings.DEFAULT_BATCH_FETCH_SIZE, value = "10"),
+				@Setting(name = AvailableSettings.FORMAT_SQL, value = "false"),
+		}
+)
+@JiraKey("HHH-17670")
+public class BatchSubselectCollection3Test {
+
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					session.persist( new SimpleA( 1L ) );
+					session.persist( new SimpleA( 2L ) );
+
+					session.persist( new SimpleC( 1L ) );
+					session.persist( new SimpleC( 2L ) );
+				}
+		);
+	}
+
+	@Test
+	public void testQuery(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					// To trigger the NPE, it is vital to have a OneToManyTableGroup before the table group that is selected
+					session.createQuery( "select obj2 from SimpleA obj left outer join obj.children obj1, SimpleC obj2" )
+							.getResultList();
+				}
+		);
+	}
+
+	@Entity(name = "SimpleA")
+	public static class SimpleA {
+		@Id
+		private Long id;
+		@OneToMany(mappedBy = "parent")
+		private List<SimpleB> children = new ArrayList<>();
+
+		public SimpleA() {
+		}
+
+		public SimpleA(Long id) {
+			this.id = id;
+		}
+	}
+
+	@Entity(name = "SimpleB")
+	public static class SimpleB {
+		@Id
+		private Long id;
+		@ManyToOne
+		private SimpleA parent;
+	}
+
+	@Entity(name = "SimpleC")
+	public static class SimpleC {
+		@Id
+		private Long id;
+		private String s;
+		@OneToMany
+		@Fetch(FetchMode.SUBSELECT)
+		private List<SimpleD> children2 = new ArrayList<>();
+
+		public SimpleC() {
+		}
+
+		public SimpleC(Long id) {
+			this.id = id;
+		}
+	}
+
+	@Entity(name = "SimpleD")
+	public static class SimpleD {
+		@Id
+		private Long id;
+		private String s;
+	}
+}