introduce incubating Assignment API

Author: gavinking

hibernate-core/src/main/java/org/hibernate/proxy/pojo/BasicLazyInitializer.java

@@ -86,7 +86,6 @@ else if ( method.equals( setIdentifierMethod ) ) {
 
 		// otherwise:
 		return INVOKE_IMPLEMENTATION;
-
 	}
 
 	private Object getReplacement() {

hibernate-core/src/main/java/org/hibernate/query/assignment/Assignment.java

@@ -0,0 +1,60 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.query.assignment;
+
+
+import jakarta.persistence.metamodel.SingularAttribute;
+import org.hibernate.Incubating;
+import org.hibernate.query.restriction.Path;
+import org.hibernate.query.sqm.tree.update.SqmUpdateStatement;
+
+/**
+ * An assignment to a field or property of an entity or embeddable.
+ *
+ * @param <T> The target entity type of the assignment
+ *
+ * @since 7.2
+ *
+ * @author Gavin King
+ */
+@Incubating
+public interface Assignment<T> {
+
+	/**
+	 * An assigment of the given literal value to the given attribute
+	 * of the root entity.
+	 */
+	static <T,X> Assignment<T> set(SingularAttribute<T,X> attribute, X value) {
+		return new AttributeAssignment<>( attribute, value );
+	}
+
+	/**
+	 * An assigment of the given literal value to the entity or embeddable
+	 * field or property identified by the given path from the root entity.
+	 */
+	static <T,X> Assignment<T> set(Path<T,X> path, X value) {
+		return new PathAssignment<>( path, value );
+	}
+
+	/**
+	 * An assigment of the entity or embeddable field or property identified
+	 * by the given path from the root entity to the given attribute of the
+	 * root entity.
+	 */
+	static <T,X> Assignment<T> set(SingularAttribute<T,X> attribute, Path<T,X> value) {
+		return new PathToAttributeAssignment<>( attribute, value );
+	}
+
+	/**
+	 * An assigment of one entity or embeddable field or property to another
+	 * entity or embeddable field or property, each identified by a given path
+	 * from the root entity.
+	 */
+	static <T,X> Assignment<T> set(Path<T,X> path, Path<T,X> value) {
+		return new PathToPathAssignment<>( path, value );
+	}
+
+	void apply(SqmUpdateStatement<? extends T> update);
+}

hibernate-core/src/main/java/org/hibernate/query/assignment/AttributeAssignment.java

@@ -0,0 +1,21 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.query.assignment;
+
+import jakarta.persistence.metamodel.SingularAttribute;
+import org.hibernate.query.sqm.tree.update.SqmUpdateStatement;
+
+/**
+ * Assignment of a value to an attribute.
+ *
+ * @author Gavin King
+ */
+record AttributeAssignment<T, X>(SingularAttribute<T, X> attribute, X value)
+		implements Assignment<T> {
+	@Override
+	public void apply(SqmUpdateStatement<? extends T> update) {
+		update.set( attribute, value );
+	}
+}

hibernate-core/src/main/java/org/hibernate/query/assignment/PathAssignment.java

@@ -0,0 +1,21 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.query.assignment;
+
+import org.hibernate.query.restriction.Path;
+import org.hibernate.query.sqm.tree.update.SqmUpdateStatement;
+
+/**
+ * Assignment of a value to a path.
+ *
+ * @author Gavin King
+ */
+record PathAssignment<T, X>(Path<T, X> path, X value)
+		implements Assignment<T> {
+	@Override
+	public void apply(SqmUpdateStatement<? extends T> update) {
+		update.set( path.path( update.getRoot() ), value );
+	}
+}

hibernate-core/src/main/java/org/hibernate/query/assignment/PathToAttributeAssignment.java

@@ -0,0 +1,22 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.query.assignment;
+
+import jakarta.persistence.metamodel.SingularAttribute;
+import org.hibernate.query.restriction.Path;
+import org.hibernate.query.sqm.tree.update.SqmUpdateStatement;
+
+/**
+ * Assignment of a path to an attribute.
+ *
+ * @author Gavin King
+ */
+record PathToAttributeAssignment<T, X>(SingularAttribute<T, X> attribute, Path<T,X> value)
+		implements Assignment<T> {
+	@Override
+	public void apply(SqmUpdateStatement<? extends T> update) {
+		update.set( attribute, value.path( update.getRoot() ) );
+	}
+}

hibernate-core/src/main/java/org/hibernate/query/assignment/PathToPathAssignment.java

@@ -0,0 +1,21 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.query.assignment;
+
+import org.hibernate.query.restriction.Path;
+import org.hibernate.query.sqm.tree.update.SqmUpdateStatement;
+
+/**
+ *  * Assignment of a path to a path.
+ *
+ * @author Gavin King
+ */
+record PathToPathAssignment<T, X>(Path<T, X> path, Path<T,X> value)
+		implements Assignment<T> {
+	@Override
+	public void apply(SqmUpdateStatement<? extends T> update) {
+		update.set( path.path( update.getRoot() ), value.path( update.getRoot() ) );
+	}
+}

hibernate-core/src/main/java/org/hibernate/query/assignment/package-info.java

@@ -0,0 +1,10 @@
+/**
+ * Support for {@linkplain org.hibernate.query.assignment.Assignment assignment}
+ * with {@link org.hibernate.query.specification.MutationSpecification}.
+ *
+ * @since 7.2
+ */
+@Incubating
+package org.hibernate.query.assignment;
+
+import org.hibernate.Incubating;

hibernate-core/src/main/java/org/hibernate/query/specification/MutationSpecification.java

@@ -16,7 +16,9 @@
 import org.hibernate.StatelessSession;
 import org.hibernate.query.IllegalMutationQueryException;
 import org.hibernate.query.MutationQuery;
+import org.hibernate.query.assignment.Assignment;
 import org.hibernate.query.specification.internal.MutationSpecificationImpl;
+import org.hibernate.query.specification.internal.MutationSpecificationImpl.MutationType;
 import org.hibernate.query.restriction.Restriction;
 
 /**
@@ -51,6 +53,20 @@ public interface MutationSpecification<T> extends QuerySpecification<T> {
 	@Override
 	MutationSpecification<T> restrict(Restriction<? super T> restriction);
 
+	/**
+	 * If this {@code MutationSpecification} represents an {@code update}
+	 * statement, add an assigment to a field or property of the target
+	 * entity.
+	 *
+	 * @param assignment The assignment to add
+	 *
+	 * @return {@code this} for method chaining.
+	 *
+	 * @since 7.2
+	 */
+	@Incubating
+	MutationSpecification<T> assign(Assignment<? super T> assignment);
+
 	/**
 	 * A function capable of modifying or augmenting a criteria query.
 	 *
@@ -131,4 +147,30 @@ static <T> MutationSpecification<T> create(CriteriaUpdate<T> criteriaUpdate) {
 	static <T> MutationSpecification<T> create(CriteriaDelete<T> criteriaDelete) {
 		return new MutationSpecificationImpl<>( criteriaDelete );
 	}
+
+	/**
+	 * Returns a specification reference which can be used to programmatically,
+	 * iteratively build a {@linkplain MutationQuery} which updates the given
+	 * entity type..
+	 *
+	 * @param targetEntityClass The target entity type
+	 *
+	 * @param <T> The root entity type for the mutation (the "target").
+	 */
+	static <T> MutationSpecification<T> createUpdate(Class<T> targetEntityClass) {
+		return new MutationSpecificationImpl<>( MutationType.UPDATE, targetEntityClass );
+	}
+
+	/**
+	 * Returns a specification reference which can be used to programmatically,
+	 * iteratively build a {@linkplain MutationQuery} which deletes the given
+	 * entity type.
+	 *
+	 * @param targetEntityClass The target entity type
+	 *
+	 * @param <T> The root entity type for the mutation (the "target").
+	 */
+	static <T> MutationSpecification<T> createDelete(Class<T> targetEntityClass) {
+		return new MutationSpecificationImpl<>( MutationType.DELETE, targetEntityClass );
+	}
 }

hibernate-core/src/main/java/org/hibernate/query/specification/internal/MutationSpecificationImpl.java

@@ -16,6 +16,7 @@
 import org.hibernate.SharedSessionContract;
 import org.hibernate.StatelessSession;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.query.assignment.Assignment;
 import org.hibernate.query.specification.MutationSpecification;
 import org.hibernate.query.IllegalMutationQueryException;
 import org.hibernate.query.MutationQuery;
@@ -49,27 +50,44 @@
  */
 public class MutationSpecificationImpl<T> implements MutationSpecification<T>, TypedQueryReference<Void> {
 
+	public enum MutationType {
+//		INSERT,
+		UPDATE,
+		DELETE
+	}
+
 	private final List<BiConsumer<SqmDeleteOrUpdateStatement<T>, SqmRoot<T>>> specifications = new ArrayList<>();
 	private final String hql;
 	private final Class<T> mutationTarget;
 	private final SqmDeleteOrUpdateStatement<T> deleteOrUpdateStatement;
+	private final MutationType type;
 
 	public MutationSpecificationImpl(String hql, Class<T> mutationTarget) {
 		this.hql = hql;
 		this.mutationTarget = mutationTarget;
 		this.deleteOrUpdateStatement = null;
+		this.type = null;
 	}
 
 	public MutationSpecificationImpl(CriteriaUpdate<T> criteriaQuery) {
 		this.deleteOrUpdateStatement = (SqmUpdateStatement<T>) criteriaQuery;
 		this.mutationTarget = deleteOrUpdateStatement.getTarget().getManagedType().getJavaType();
 		this.hql = null;
+		this.type = MutationType.UPDATE;
 	}
 
 	public MutationSpecificationImpl(CriteriaDelete<T> criteriaQuery) {
 		this.deleteOrUpdateStatement = (SqmDeleteStatement<T>) criteriaQuery;
 		this.mutationTarget = deleteOrUpdateStatement.getTarget().getManagedType().getJavaType();
 		this.hql = null;
+		this.type = MutationType.DELETE;
+	}
+
+	public MutationSpecificationImpl(MutationType type, Class<T> mutationTarget) {
+		this.deleteOrUpdateStatement = null;
+		this.mutationTarget = mutationTarget;
+		this.hql = null;
+		this.type = type;
 	}
 
 	@Override
@@ -104,6 +122,19 @@ public MutationSpecification<T> restrict(Restriction<? super T> restriction) {
 		return this;
 	}
 
+	@Override
+	public MutationSpecification<T> assign(Assignment<? super T> assignment) {
+		specifications.add( (sqmStatement, mutationTargetRoot) -> {
+			if ( sqmStatement instanceof SqmUpdateStatement<T> sqmUpdateStatement ) {
+				assignment.apply( sqmUpdateStatement );
+			}
+			else {
+				throw new IllegalStateException( "Delete query cannot perform assignment" );
+			}
+		} );
+		return this;
+	}
+
 	@Override
 	public MutationSpecification<T> augment(Augmentation<T> augmentation) {
 		specifications.add( (sqmStatement, mutationTargetRoot) ->
@@ -139,6 +170,14 @@ else if ( deleteOrUpdateStatement != null ) {
 			mutationTargetRoot = resolveSqmRoot( sqmStatement,
 					sqmStatement.getTarget().getManagedType().getJavaType() );
 		}
+		else if ( type != null ) {
+			final var criteriaBuilder = queryEngine.getCriteriaBuilder();
+			sqmStatement = switch ( type ) {
+				case UPDATE -> criteriaBuilder.createCriteriaUpdate( mutationTarget );
+				case DELETE -> criteriaBuilder.createCriteriaDelete( mutationTarget );
+			};
+			mutationTargetRoot = sqmStatement.getTarget();
+		}
 		else {
 			throw new AssertionFailure( "No HQL or criteria" );
 		}