HHH-18829 Auto generate record ID class if no explicit @IdClass

hibernate-core/src/main/java/org/hibernate/boot/model/internal/EntityBinder.java

@@ -481,10 +481,22 @@ private boolean mapAsIdClass(
 		final ClassDetails classWithIdClass = inheritanceState.getClassWithIdClass( false );
 		if ( classWithIdClass != null ) {
 			final IdClass idClassAnn = classWithIdClass.getDirectAnnotationUsage( IdClass.class );
-			final Class<?> idClassValue = idClassAnn.value();
-			final ClassDetails compositeClass =
-					getMetadataCollector().getSourceModelBuildingContext().getClassDetailsRegistry()
-							.resolveClassDetails( idClassValue.getName() );
+			final ClassDetails compositeClass;
+			if ( idClassAnn == null ) {
+				try {
+					compositeClass = getMetadataCollector().getSourceModelBuildingContext()
+							.getClassDetailsRegistry()
+							.resolveClassDetails( inheritanceState.getClassDetails().getClassName() + "_$Id" );
+				}
+				catch (RuntimeException e) {
+					return false;
+				}
+			}
+			else {
+				final Class<?> idClassValue = idClassAnn.value();
+				compositeClass = getMetadataCollector().getSourceModelBuildingContext()
+						.getClassDetailsRegistry().resolveClassDetails( idClassValue.getName() );
+			}
 			final TypeDetails compositeType = new ClassTypeDetailsImpl( compositeClass, TypeDetails.Kind.CLASS );
 			final TypeDetails classWithIdType = new ClassTypeDetailsImpl( classWithIdClass, TypeDetails.Kind.CLASS );
 

hibernate-core/src/main/java/org/hibernate/boot/model/internal/InheritanceState.java

@@ -7,6 +7,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.stream.Stream;
 
 import org.hibernate.AnnotationException;
 import org.hibernate.boot.spi.AccessType;
@@ -183,6 +184,13 @@ else if ( classDetails.hasDirectAnnotationUsage( IdClass.class ) ) {
 			return classDetails;
 		}
 		else {
+			final long count = Stream.concat(
+					classDetails.getFields().stream(),
+					classDetails.getMethods().stream()
+			).filter( t -> t.hasDirectAnnotationUsage( Id.class ) ).count();
+			if ( count > 1 ) {
+				return classDetails;
+			}
 			final InheritanceState state = getSuperclassInheritanceState( classDetails, inheritanceStatePerClass );
 			if ( state != null ) {
 				return state.getClassWithIdClass( true );

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/derivedidentities/bidirectional/Order.java

@@ -13,9 +13,11 @@
 import jakarta.persistence.Id;
 import jakarta.persistence.OneToMany;
 import jakarta.persistence.Table;
+import org.hibernate.annotations.processing.Exclude;
 
 @SuppressWarnings("serial")
 @Entity
+@Exclude
 @Table(name = "orders")
 public class Order implements Serializable
 {

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/derivedidentities/bidirectional/OrderLine.java

@@ -10,9 +10,11 @@
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
 import jakarta.persistence.Table;
+import org.hibernate.annotations.processing.Exclude;
 
 @SuppressWarnings("serial")
 @Entity
+@Exclude
 @Table(name = "order_line")
 // @IdClass(OrderLinePK.class)
 public class OrderLine implements Serializable

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/derivedidentities/bidirectional/Product.java

@@ -9,9 +9,11 @@
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
+import org.hibernate.annotations.processing.Exclude;
 
 @SuppressWarnings("serial")
 @Entity
+@Exclude
 @Table(name = "products")
 public class Product implements Serializable
 {

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/hhh18829/AutoGeneratedIdClassTest.java

@@ -0,0 +1,52 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.mapping.hhh18829;
+
+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.lang.reflect.InvocationTargetException;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@DomainModel(annotatedClasses = EmployeeWithoutIdClass.class)
+@JiraKey(" HHH-18829")
+@SessionFactory
+public class AutoGeneratedIdClassTest {
+
+	@BeforeAll
+	void setUp(SessionFactoryScope sessionFactoryScope) {
+		sessionFactoryScope.inTransaction( sess -> {
+			final var one = new EmployeeWithoutIdClass();
+			one.empName = "John Doe";
+			one.empId = 1;
+			one.address = "10 Downing Street, SW1A 2AA";
+			sess.persist( one );
+
+			final var two = new EmployeeWithoutIdClass();
+			two.empName = "Dave Default";
+			two.empId = 1;
+			two.address = "1600 Pennsylvania Avenue";
+			sess.persist( two );
+		} );
+	}
+
+	@Test
+	public void test(SessionFactoryScope sessionFactoryScope)
+			throws ClassNotFoundException, InvocationTargetException, InstantiationException, IllegalAccessException {
+		final var idClass = Class.forName( EmployeeWithoutIdClass.class.getName() + "_$Id" );
+		final var id = idClass.getConstructors()[0].newInstance( "John Doe", 1 );
+		final var employees = sessionFactoryScope.fromSession(
+				sess -> sess.createQuery( "from EmployeeWithoutIdClass where id=:id", EmployeeWithoutIdClass.class ).setParameter( "id", id )
+						.getResultList()
+		);
+		assertEquals( 1, employees.size() );
+		assertEquals( "10 Downing Street, SW1A 2AA", employees.get( 0 ).address );
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/hhh18829/EmployeeWithoutIdClass.java

@@ -0,0 +1,17 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.mapping.hhh18829;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+@Entity
+public class EmployeeWithoutIdClass {
+	@Id
+	String empName;
+	@Id
+	Integer empId;
+	String address;
+}

tooling/metamodel-generator/src/main/java/org/hibernate/processor/annotation/AnnotationMetaEntity.java

@@ -108,6 +108,8 @@
  */
 public class AnnotationMetaEntity extends AnnotationMeta {
 
+	private static final String ID_CLASS_MEMBER_NAME = "<ID_CLASS>";
+
 	private final ImportContext importContext;
 	private final TypeElement element;
 	private final Map<String, MetaAttribute> members;
@@ -443,6 +445,8 @@ && containsAnnotation( method, HQL, SQL, FIND ) ) {
 
 			addPersistentMembers( fieldsOfClass, AccessType.FIELD );
 			addPersistentMembers( gettersAndSettersOfClass, AccessType.PROPERTY );
+
+			addIdClassIfNeeded( fieldsOfClass, gettersAndSettersOfClass );
 		}
 
 		addAuxiliaryMembers();
@@ -456,6 +460,33 @@ && containsAnnotation( method, HQL, SQL, FIND ) ) {
 		initialized = true;
 	}
 
+	private void addIdClassIfNeeded(List<? extends Element> fields, List<? extends Element> methods) {
+		if ( hasAnnotation( element, ID_CLASS ) ) {
+			return;
+		}
+		final List<MetaAttribute> components = new ArrayList<>();
+		for ( Element field : fields ) {
+			if ( hasAnnotation( field, ID ) && isPersistent( field, AccessType.FIELD ) ) {
+				final String propertyName = propertyName( this, field );
+				if ( members.containsKey( propertyName ) ) {
+					components.add( members.get( propertyName ) );
+				}
+			}
+		}
+		for ( Element method : methods ) {
+			if ( hasAnnotation( method, ID ) && isPersistent( method, AccessType.PROPERTY ) ) {
+				final String propertyName = propertyName( this, method );
+				if ( members.containsKey( propertyName ) ) {
+					components.add( members.get( propertyName ) );
+				}
+			}
+		}
+		if ( components.size() < 2 ) {
+			return;
+		}
+		putMember( ID_CLASS_MEMBER_NAME, new IdClassMetaAttribute( this, components ) );
+	}
+
 	private boolean checkEntities(List<ExecutableElement> lifecycleMethods) {
 		boolean foundPersistenceEntity = false;
 		VariableElement nonPersistenceParameter = null;

tooling/metamodel-generator/src/main/java/org/hibernate/processor/annotation/AnnotationMetaSingleAttribute.java

@@ -4,11 +4,15 @@
  */
 package org.hibernate.processor.annotation;
 
+import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.Element;
 
 import org.hibernate.processor.model.MetaSingleAttribute;
 import org.hibernate.processor.util.Constants;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * @author Max Andersen
  * @author Hardy Ferentschik
@@ -24,4 +28,9 @@ public AnnotationMetaSingleAttribute(AnnotationMetaEntity parent, Element elemen
 	public final String getMetaType() {
 		return Constants.SINGULAR_ATTRIBUTE;
 	}
+
+	@Override
+	public List<AnnotationMirror> inheritedAnnotations() {
+		return new ArrayList<>(element.getAnnotationMirrors());
+	}
 }

tooling/metamodel-generator/src/main/java/org/hibernate/processor/annotation/IdClassMetaAttribute.java

@@ -0,0 +1,73 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.processor.annotation;
+
+import org.hibernate.processor.model.MetaAttribute;
+import org.hibernate.processor.model.Metamodel;
+
+import java.util.List;
+
+public class IdClassMetaAttribute implements MetaAttribute {
+
+	private final Metamodel parent;
+
+	private final List<MetaAttribute> components;
+
+	public IdClassMetaAttribute(Metamodel parent, List<MetaAttribute> components) {
+		this.parent = parent;
+		this.components = components;
+	}
+
+	@Override
+	public boolean hasTypedAttribute() {
+		return true;
+	}
+
+	@Override
+	public boolean hasStringAttribute() {
+		return false;
+	}
+
+	@Override
+	public String getAttributeDeclarationString() {
+		final StringBuilder decl = new StringBuilder()
+				.append("\n/**\n * Static ID class for {@link ")
+				.append( parent.getQualifiedName() )
+				.append( "}\n **/\n" )
+				.append( "public record Id" );
+		String delimiter = "(";
+		for ( MetaAttribute component : components ) {
+			decl.append( delimiter ).append( parent.importType( component.getTypeDeclaration() ) )
+					.append( ' ' ).append( component.getPropertyName() );
+			delimiter = ", ";
+		}
+		return decl.append( ") {}" ).toString();
+	}
+
+	@Override
+	public String getAttributeNameDeclarationString() {
+		return "";
+	}
+
+	@Override
+	public String getMetaType() {
+		return "";
+	}
+
+	@Override
+	public String getPropertyName() {
+		return "";
+	}
+
+	@Override
+	public String getTypeDeclaration() {
+		return "";
+	}
+
+	@Override
+	public Metamodel getHostingEntity() {
+		return parent;
+	}
+}

tooling/metamodel-generator/src/test/java/org/hibernate/processor/test/hhh18829/Address.java

@@ -0,0 +1,12 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.processor.test.hhh18829;
+
+import jakarta.persistence.MappedSuperclass;
+
+@MappedSuperclass
+public class Address {
+	String address;
+}

tooling/metamodel-generator/src/test/java/org/hibernate/processor/test/hhh18829/AnotherEmployee.java

@@ -0,0 +1,33 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.processor.test.hhh18829;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+@Entity
+public class AnotherEmployee extends Address {
+	Integer empId;
+
+	String empName;
+
+	@Id
+	public Integer getEmpId() {
+		return empId;
+	}
+
+	public void setEmpId(Integer empId) {
+		this.empId = empId;
+	}
+
+	@Id
+	public String getEmpName() {
+		return empName;
+	}
+
+	public void setEmpName(String empName) {
+		this.empName = empName;
+	}
+}