WIP Criteria aliasing fix

hibernate-core/src/main/java/org/hibernate/query/criteria/internal/Renderable.java

@@ -7,6 +7,8 @@
 package org.hibernate.query.criteria.internal;
 
 
+import javax.persistence.criteria.Selection;
+
 import org.hibernate.query.criteria.internal.compile.RenderingContext;
 
 /**
@@ -31,7 +33,15 @@ public interface Renderable {
 	 * @return rendered expression
 	 */
 	default String renderProjection(RenderingContext renderingContext) {
-		return render( renderingContext );
+		final String expression = render( renderingContext );
+		if ( this instanceof Selection<?> ) {
+			final Selection<?> selection = (Selection<?>) this;
+			final String alias = selection.getAlias();
+			if ( alias != null ) {
+				return expression + " as " + alias;
+			}
+		}
+		return expression;
 	}
 
 	/**

hibernate-core/src/main/java/org/hibernate/query/criteria/internal/expression/CompoundSelectionImpl.java

@@ -72,6 +72,10 @@ public void registerParameters(ParameterRegistry registry) {
 		}
 	}
 
+	public String renderProjection(RenderingContext renderingContext) {
+		return render( renderingContext );
+	}
+
 	public String render(RenderingContext renderingContext) {
 		StringBuilder buff = new StringBuilder();
 		if ( isConstructor ) {

hibernate-core/src/main/java/org/hibernate/query/criteria/internal/expression/LiteralExpression.java

@@ -78,15 +78,17 @@ private String bindLiteral(RenderingContext renderingContext) {
 
 	@SuppressWarnings({ "unchecked" })
 	public String renderProjection(RenderingContext renderingContext) {
+		final String alias = getAlias();
+		final String projectionExtension = alias == null ? "" : " as " + alias;
 		if ( ValueHandlerFactory.isCharacter( literal ) ) {
 			// In case literal is a Character, pass literal.toString() as the argument.
-			return renderingContext.getDialect().inlineLiteral( literal.toString() );
+			return renderingContext.getDialect().inlineLiteral( literal.toString() ) + projectionExtension;
 		}
 
 		// some drivers/servers do not like parameters in the select clause
 		final ValueHandlerFactory.ValueHandler handler =
 				ValueHandlerFactory.determineAppropriateHandler( literal.getClass() );
-		return handler.render( literal );
+		return handler.render( literal ) + projectionExtension;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/query/criteria/internal/expression/NullLiteralExpression.java

@@ -32,6 +32,8 @@ public String render(RenderingContext renderingContext) {
 	}
 
 	public String renderProjection(RenderingContext renderingContext) {
-		return CastFunction.CAST_NAME + "( 	null  as " + renderingContext.getCastType( getJavaType() ) + ')';
+		final String alias = getAlias();
+		final String projectionExtension = alias == null ? "" : " as " + alias;
+		return CastFunction.CAST_NAME + "( 	null  as " + renderingContext.getCastType( getJavaType() ) + ')' + projectionExtension;
 	}
 }

hibernate-core/src/main/java/org/hibernate/query/criteria/internal/expression/SearchedCaseExpression.java

@@ -113,10 +113,12 @@ public String render(RenderingContext renderingContext) {
 	}
 
 	public String renderProjection(RenderingContext renderingContext) {
+		final String alias = getAlias();
+		final String projectionExtension = alias == null ? "" : " as " + alias;
 		return render(
 				renderingContext,
 				(Renderable expression, RenderingContext context) -> expression.renderProjection( context )
-		);
+		) + projectionExtension;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/query/criteria/internal/expression/SimpleCaseExpression.java

@@ -126,10 +126,12 @@ public String render(RenderingContext renderingContext) {
 
 	@Override
 	public String renderProjection(RenderingContext renderingContext) {
+		final String alias = getAlias();
+		final String projectionExtension = alias == null ? "" : " as " + alias;
 		return render(
 				renderingContext,
 				(Renderable expression, RenderingContext context) -> expression.renderProjection( context )
-		);
+		) + projectionExtension;
 	}
 
 	@Override

hibernate-core/src/test/java/org/hibernate/jpa/test/criteria/CriteriaAliasTest.java

@@ -0,0 +1,135 @@
+/*
+ * 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.jpa.test.criteria;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutput;
+import java.io.ObjectOutputStream;
+import java.util.Arrays;
+import java.util.List;
+import javax.persistence.Tuple;
+import javax.persistence.TypedQuery;
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Root;
+import javax.persistence.metamodel.EntityType;
+
+import org.hibernate.CacheMode;
+import org.hibernate.ScrollMode;
+import org.hibernate.ScrollableResults;
+import org.hibernate.Session;
+import org.hibernate.jpa.test.BaseEntityManagerFunctionalTestCase;
+import org.hibernate.jpa.test.callbacks.RemoteControl;
+import org.hibernate.jpa.test.callbacks.Television;
+import org.hibernate.jpa.test.callbacks.VideoSystem;
+import org.hibernate.jpa.test.inheritance.Fruit;
+import org.hibernate.jpa.test.inheritance.Strawberry;
+import org.hibernate.jpa.test.metamodel.Address;
+import org.hibernate.jpa.test.metamodel.Alias;
+import org.hibernate.jpa.test.metamodel.Country;
+import org.hibernate.jpa.test.metamodel.CreditCard;
+import org.hibernate.jpa.test.metamodel.Customer;
+import org.hibernate.jpa.test.metamodel.Info;
+import org.hibernate.jpa.test.metamodel.LineItem;
+import org.hibernate.jpa.test.metamodel.Order;
+import org.hibernate.jpa.test.metamodel.Phone;
+import org.hibernate.jpa.test.metamodel.Product;
+import org.hibernate.jpa.test.metamodel.ShelfLife;
+import org.hibernate.jpa.test.metamodel.Spouse;
+import org.hibernate.query.spi.QueryImplementor;
+import org.hibernate.transform.ResultTransformer;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.transaction.TransactionUtil;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.notNullValue;
+import static org.hamcrest.CoreMatchers.nullValue;
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+public class CriteriaAliasTest extends BaseEntityManagerFunctionalTestCase {
+	@Override
+	public Class[] getAnnotatedClasses() {
+		return new Class[] {
+				Customer.class,
+				Alias.class,
+				Phone.class,
+				Address.class,
+				Country.class,
+				CreditCard.class,
+				Info.class,
+				Spouse.class,
+				LineItem.class,
+				Order.class,
+				Product.class,
+				ShelfLife.class,
+				// @Inheritance
+				Fruit.class,
+				Strawberry.class,
+				// @MappedSuperclass
+				VideoSystem.class,
+				Television.class,
+				RemoteControl.class
+		};
+	}
+
+	@Before
+	public void setUp(){
+		TransactionUtil.doInJPA( this::entityManagerFactory, entityManager -> {
+			Customer customer = new Customer();
+			customer.setId( "id" );
+			customer.setName( " David R. Vincent " );
+			entityManager.persist( customer );
+		} );
+	}
+
+	@Test
+	@TestForIssue(jiraKey = "HHH-")
+	public void testAliasJPACriteriaQuery() {
+		TransactionUtil.doInJPA( this::entityManagerFactory, entityManager -> {
+			final CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
+			final CriteriaQuery<Tuple> query = criteriaBuilder.createTupleQuery();
+			final Root<Customer> from = query.from( Customer.class );
+			query.multiselect(
+					from.get( "id" ),
+					from.get( "name" ).alias( "name" ),
+					from.get( "age" ).alias( "alter" )
+			);
+
+			final MyResultTransformer transformer = new MyResultTransformer();
+			entityManager.createQuery( query )
+					.unwrap( QueryImplementor.class )
+					.setResultTransformer( transformer )
+					.getResultList();
+			assertThat( transformer.aliases, is(notNullValue()) );
+			assertThat( transformer.aliases.length, is( 3 ) );
+			assertThat( transformer.aliases[0], is(nullValue()) );
+			assertThat( transformer.aliases[1], is( "name" ) );
+			assertThat( transformer.aliases[2], is( "alter" ) );
+		} );
+	}
+
+	private static class MyResultTransformer implements ResultTransformer {
+		String[] aliases;
+
+		@Override
+		public Object transformTuple(Object[] tuple, String[] aliases) {
+			this.aliases = aliases;
+			return tuple;
+		}
+
+		@Override
+		public List transformList(List collection) {
+			return collection;
+		}
+	}
+}