HHH-18979 add equalIgnoringCase()

Author: gavinking

hibernate-core/src/main/java/org/hibernate/query/Restriction.java

@@ -66,6 +66,10 @@ static <T,U> Restriction<T> unequal(SingularAttribute<T,U> attribute, U value) {
 		return equal(attribute, value).negated();
 	}
 
+	static <T> Restriction<T> equalIgnoringCase(SingularAttribute<T,String> attribute, String value) {
+		return restrict( attribute, Range.singleCaseInsensitiveValue(value) );
+	}
+
 	static <T,U> Restriction<T> in(SingularAttribute<T,U> attribute, java.util.List<U> values) {
 		return restrict( attribute, Range.valueList(values) );
 	}

hibernate-core/src/main/java/org/hibernate/query/range/CaseInsensitiveValue.java

@@ -0,0 +1,28 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.query.range;
+
+import jakarta.persistence.criteria.CriteriaBuilder;
+import jakarta.persistence.criteria.Expression;
+import jakarta.persistence.criteria.Path;
+import jakarta.persistence.criteria.Predicate;
+import jakarta.persistence.metamodel.SingularAttribute;
+
+import java.util.Locale;
+
+/**
+ * Restricts to a single literal string, ignoring case.
+ */
+record CaseInsensitiveValue(String value) implements Range<String> {
+	@Override
+	public <X> Predicate toPredicate(Path<? extends X> root, SingularAttribute<X, String> attribute, CriteriaBuilder builder) {
+		// TODO: it would be much better to not do use literal,
+		//       and let it be treated as a parameter, but we
+		//       we run into the usual bug with parameters in
+		//       manipulated SQM trees
+		final Expression<String> literal = builder.literal( value.toLowerCase( Locale.ROOT ) );
+		return builder.lower( root.get( attribute ) ).equalTo( literal );
+	}
+}

hibernate-core/src/main/java/org/hibernate/query/range/Range.java

@@ -38,6 +38,10 @@ static <U> Range<U> singleValue(U value) {
 		return new Value<>( value );
 	}
 
+	static Range<String> singleCaseInsensitiveValue(String value) {
+		return new CaseInsensitiveValue( value );
+	}
+
 	static <U> Range<U> valueList(java.util.List<U> values) {
 		return new List<>( values );
 	}

hibernate-core/src/test/java/org/hibernate/orm/test/query/restriction/RestrictionTest.java

@@ -69,6 +69,11 @@ void test(SessionFactoryScope scope) {
 						.addRestriction( Restriction.between( pages, 150, 400 ) )
 						.getResultList() );
 		assertEquals( 1, booksByPageRange.size() );
+		Book bookByTitle = scope.fromSession( session ->
+				session.createSelectionQuery( "from Book", Book.class)
+						.addRestriction( Restriction.equalIgnoringCase( title, "hibernate in action" ) )
+						.getSingleResultOrNull() );
+		assertEquals( "9781932394153", bookByTitle.isbn );
 	}
 
 	@Entity(name="Book")