Reference collection via join in jpql.

Author: christophstrobl

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java

@@ -481,7 +481,10 @@ public JpqlQueryBuilder.Predicate build() {
 				case NOT_CONTAINING:
 
 					if (property.getLeafProperty().isCollection()) {
-						where = JpqlQueryBuilder.where(entity, property);
+
+						if (!property.hasNext()) {
+							where = JpqlQueryBuilder.where(entity, property);
+						}
 
 						return type.equals(NOT_CONTAINING) ? where.notMemberOf(placeholder(provider.next(part)))
 								: where.memberOf(placeholder(provider.next(part)));
@@ -522,7 +525,10 @@ public JpqlQueryBuilder.Predicate build() {
 						throw new IllegalArgumentException("IsEmpty / IsNotEmpty can only be used on collection properties");
 					}
 
-					where = JpqlQueryBuilder.where(entity, property);
+					if (!property.hasNext()) {
+						where = JpqlQueryBuilder.where(entity, property);
+					}
+
 					return type.equals(IS_NOT_EMPTY) ? where.isNotEmpty() : where.isEmpty();
 				case WITHIN:
 				case NEAR:

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JpqlUtils.java

@@ -97,6 +97,11 @@ public JpqlQueryBuilder.PathExpression toExpressionRecursively(Metamodel metamod
 				throw new IllegalStateException("Binding property is null");
 			}
 
+			// this is a reference to a collection property (eg. for an is empty check)
+			if (nextAttribute.isCollection() && !nextProperty.hasNext()) {
+				return new JpqlQueryBuilder.PathAndOrigin(nextProperty, joinSource, false);
+			}
+
 			return toExpressionRecursively(metamodel, joinSource, (Bindable<?>) nextAttribute, nextProperty, isForSelection,
 					requiresOuterJoin);
 		}

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/UserRepositoryFinderTests.java

@@ -167,6 +167,17 @@ void executesNotInQueryCorrectly() {
 		assertThat(result).containsExactly(oliver);
 	}
 
+	@Test // GH-4110
+	void executesQueryWithEmptyOnCollection() {
+
+		dave.addColleague(oliver);
+		userRepository.save(dave);
+		userRepository.save(oliver);
+
+		assertThat(userRepository.findByColleaguesRolesIsEmpty()).containsExactly(dave, carter);
+		assertThat(userRepository.findByColleaguesRolesIsNotEmpty()).containsExactlyInAnyOrder(oliver);
+	}
+
 	@Test // DATAJPA-92
 	void findsByLastnameIgnoringCase() {
 

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/JpqlQueryBuilderUnitTests.java

@@ -248,6 +248,22 @@ void shouldRenderJoinsWithSamePathSegmentCorrectly() {
 
 	}
 
+	@Test // GH-4110
+	void referencesCollectionViaJoin() {
+
+		TestMetaModel model = TestMetaModel.hibernateModel(Race.class, Groups.class, Group.class, GroupId.class,
+				Person.class);
+		Entity entity = entity(Race.class);
+
+		EntityType<Race> entityType = model.entity(Race.class);
+		JpqlQueryBuilder.PathExpression pas = JpqlUtils.toExpressionRecursively(model, entity, entityType,
+				PropertyPath.from("lineup.groups", Race.class));
+		String jpql = JpqlQueryBuilder.selectFrom(entity).entity().where(JpqlQueryBuilder.where(pas).isNotEmpty()).render();
+
+		assertThat(jpql).isEqualTo(
+				"SELECT r FROM JpqlQueryBuilderUnitTests$Race r LEFT JOIN r.lineup l WHERE l.groups IS NOT EMPTY");
+	}
+
 	static ContextualAssert contextual(RenderContext context) {
 		return new ContextualAssert(context);
 	}
@@ -348,6 +364,13 @@ static class Groups {
 
 	}
 
+	@jakarta.persistence.Entity
+	static class Race {
+
+		@Id long id;
+		@OneToMany Set<Groups> lineup;
+	}
+
 	@jakarta.persistence.Entity
 	static class Group {
 

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java

@@ -146,6 +146,10 @@ Window<User> findTop3ByFirstnameStartingWithOrderByFirstnameAscEmailAddressAsc(S
 
 	List<User> findByFirstnameNotIn(Collection<String> firstnames);
 
+	List<User> findByColleaguesRolesIsEmpty();
+
+	List<User> findByColleaguesRolesIsNotEmpty();
+
 	// DATAJPA-292
 	@Query("select u from User u where u.firstname like ?1%")
 	List<User> findByFirstnameLike(String firstname);