HHH-17724 add count(*) to HibernateCriteriaBuilder

and remove some unused type parameters

Author: gavinking

hibernate-core/src/main/java/org/hibernate/query/criteria/HibernateCriteriaBuilder.java

@@ -389,6 +389,11 @@ default <T> JpaSubQuery<T> except(Subquery<? extends T> query1, Subquery<?>... q
 	@Override
 	JpaExpression<Long> countDistinct(Expression<?> x);
 
+	/**
+	 * Equivalent to HQL {@code count(*)}.
+	 */
+	JpaExpression<Long> count();
+
 	@Override
 	<N extends Number> JpaExpression<N> neg(Expression<N> x);
 
@@ -2680,15 +2685,15 @@ <T> JpaExpression<T[]> arrayAgg(
 	 * @since 6.4
 	 */
 	@Incubating
-	<T> JpaExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, Expression<String> separatorExpression);
+	JpaExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, Expression<String> separatorExpression);
 
 	/**
 	 * Concatenates the non-null array elements with a separator, as specified by the arguments.
 	 *
 	 * @since 6.4
 	 */
 	@Incubating
-	<T> JpaExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, String separator);
+	JpaExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, String separator);
 
 	/**
 	 * Whether an array contains an element.

hibernate-core/src/main/java/org/hibernate/query/criteria/spi/HibernateCriteriaBuilderDelegate.java

@@ -439,6 +439,11 @@ public JpaExpression<Long> count(Expression<?> argument) {
 		return criteriaBuilder.count( argument );
 	}
 
+	@Override
+	public JpaExpression<Long> count() {
+		return criteriaBuilder.count();
+	}
+
 	@Override
 	public JpaExpression<Long> countDistinct(Expression<?> x) {
 		return criteriaBuilder.countDistinct( x );
@@ -2435,15 +2440,15 @@ public <T> JpaExpression<T[]> arrayFill(T element, Integer elementCount) {
 
 	@Override
 	@Incubating
-	public <T> JpaExpression<String> arrayToString(
+	public JpaExpression<String> arrayToString(
 			Expression<? extends Object[]> arrayExpression,
 			Expression<String> separatorExpression) {
 		return criteriaBuilder.arrayToString( arrayExpression, separatorExpression );
 	}
 
 	@Override
 	@Incubating
-	public <T> JpaExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, String separator) {
+	public JpaExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, String separator) {
 		return criteriaBuilder.arrayToString( arrayExpression, separator );
 	}
 

hibernate-core/src/main/java/org/hibernate/query/sqm/NodeBuilder.java

@@ -17,7 +17,6 @@
 import java.util.Map;
 import java.util.Set;
 
-import org.hibernate.Incubating;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.metamodel.model.domain.JpaMetamodel;
 import org.hibernate.query.NullPrecedence;
@@ -32,7 +31,6 @@
 import org.hibernate.query.criteria.JpaSearchedCase;
 import org.hibernate.query.criteria.JpaSelection;
 import org.hibernate.query.criteria.JpaSimpleCase;
-import org.hibernate.query.criteria.JpaValues;
 import org.hibernate.query.criteria.JpaWindow;
 import org.hibernate.query.spi.QueryEngine;
 import org.hibernate.query.sqm.tree.delete.SqmDeleteStatement;
@@ -240,10 +238,10 @@ <T> SqmExpression<T[]> arrayAgg(
 	<T> SqmExpression<T[]> arrayFill(T element, Integer elementCount);
 
 	@Override
-	<T> SqmExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, Expression<String> separatorExpression);
+	SqmExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, Expression<String> separatorExpression);
 
 	@Override
-	<T> SqmExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, String separator);
+	SqmExpression<String> arrayToString(Expression<? extends Object[]> arrayExpression, String separator);
 
 	@Override
 	<T> SqmPredicate arrayContains(Expression<T[]> arrayExpression, Expression<T> elementExpression);
@@ -596,6 +594,9 @@ <T> SqmExpression<T[]> arrayAgg(
 	@Override
 	SqmExpression<Long> countDistinct(Expression<?> x);
 
+	@Override
+	SqmExpression<Long> count();
+
 	@Override
 	<N extends Number> SqmExpression<N> neg(Expression<N> x);
 

hibernate-core/src/main/java/org/hibernate/query/sqm/internal/SqmCriteriaNodeBuilder.java

@@ -44,7 +44,6 @@
 import org.hibernate.metamodel.model.domain.BasicDomainType;
 import org.hibernate.metamodel.model.domain.DomainType;
 import org.hibernate.metamodel.model.domain.JpaMetamodel;
-import org.hibernate.metamodel.model.domain.SimpleDomainType;
 import org.hibernate.metamodel.model.domain.SingularPersistentAttribute;
 import org.hibernate.metamodel.model.domain.internal.BasicTypeImpl;
 import org.hibernate.metamodel.model.domain.spi.JpaMetamodelImplementor;
@@ -77,7 +76,6 @@
 import org.hibernate.query.sqm.SetOperator;
 import org.hibernate.query.sqm.SqmExpressible;
 import org.hibernate.query.sqm.SqmPathSource;
-import org.hibernate.query.sqm.SqmQuerySource;
 import org.hibernate.query.sqm.TemporalUnit;
 import org.hibernate.query.sqm.TrimSpec;
 import org.hibernate.query.sqm.UnaryArithmeticOperator;
@@ -121,6 +119,7 @@
 import org.hibernate.query.sqm.tree.expression.SqmLiteralNull;
 import org.hibernate.query.sqm.tree.expression.SqmModifiedSubQueryExpression;
 import org.hibernate.query.sqm.tree.expression.SqmOver;
+import org.hibernate.query.sqm.tree.expression.SqmStar;
 import org.hibernate.query.sqm.tree.expression.SqmToDuration;
 import org.hibernate.query.sqm.tree.expression.SqmTrimSpecification;
 import org.hibernate.query.sqm.tree.expression.SqmTuple;
@@ -182,7 +181,6 @@
 import static java.util.Arrays.asList;
 import static org.hibernate.query.internal.QueryHelper.highestPrecedenceType;
 import static org.hibernate.query.sqm.TrimSpec.fromCriteriaTrimSpec;
-import static org.hibernate.query.sqm.internal.TypecheckUtil.assertComparable;
 
 /**
  * Acts as a JPA {@link jakarta.persistence.criteria.CriteriaBuilder} by
@@ -855,6 +853,15 @@ public SqmExpression<Long> countDistinct(Expression<?> argument) {
 		);
 	}
 
+	@Override
+	public SqmExpression<Long> count() {
+		return getFunctionDescriptor( "count" ).generateSqmExpression(
+				new SqmStar( this ),
+				null,
+				queryEngine
+		);
+	}
+
 	@Override
 	public JpaExpression<Integer> sign(Expression<? extends Number> x) {
 		return getFunctionDescriptor( "sign" ).generateSqmExpression(
@@ -4280,7 +4287,7 @@ public <T> SqmExpression<T[]> arrayFill(T element, Integer elementCount) {
 	}
 
 	@Override
-	public <T> SqmExpression<String> arrayToString(
+	public SqmExpression<String> arrayToString(
 			Expression<? extends Object[]> arrayExpression,
 			Expression<String> separatorExpression) {
 		return getFunctionDescriptor( "array_to_string" ).generateSqmExpression(
@@ -4291,7 +4298,7 @@ public <T> SqmExpression<String> arrayToString(
 	}
 
 	@Override
-	public <T> SqmExpression<String> arrayToString(
+	public SqmExpression<String> arrayToString(
 			Expression<? extends Object[]> arrayExpression,
 			String separator) {
 		return getFunctionDescriptor( "array_to_string" ).generateSqmExpression(

hibernate-core/src/test/java/org/hibernate/orm/test/jpa/CountEntityWithCompositeIdTest.java

@@ -10,6 +10,7 @@
 import jakarta.persistence.criteria.CriteriaQuery;
 import jakarta.persistence.criteria.Root;
 
+import org.hibernate.query.criteria.HibernateCriteriaBuilder;
 import org.hibernate.testing.orm.junit.EntityManagerFactoryScope;
 import org.hibernate.testing.orm.junit.Jpa;
 import org.junit.jupiter.api.Test;
@@ -34,5 +35,14 @@ public void shouldCount(EntityManagerFactoryScope scope) {
                     assertThat(entityManager.createQuery(cq).getSingleResult().intValue(), is(0));
                 }
         );
+        scope.inTransaction(
+                entityManager -> {
+                    HibernateCriteriaBuilder cb = (HibernateCriteriaBuilder) entityManager.getCriteriaBuilder();
+                    CriteriaQuery<Long> cq = cb.createQuery(Long.class);
+                    cq.from(EntityWithCompositeId.class);
+                    cq.select(cb.count());
+                    assertThat(entityManager.createQuery(cq).getSingleResult().intValue(), is(0));
+                }
+        );
     }
 }