`NullPointerException` when using `Specification.where(null)` with `CriteriaBuilder`

[loic-brtd]

Hi, I wanted to to use Specification.where(null) as a "match all" org.springframework.data.jpa.domain.Specification (a specification without any restriction).

But I get a NullPointerException inside Hibernate code when using it with a CriteriaBuilder:

Specification<Task> matchAllSpecification = Specification.where(null);

CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Task> query = cb.createQuery(Task.class);

Root<Task> root = query.from(Task.class);
query.where(matchAllSpecification.toPredicate(root, query, cb));

entityManager.createQuery(query).getResultList();

Stack trace :

java.lang.NullPointerException: Cannot invoke "org.hibernate.query.sqm.tree.expression.SqmExpression.getExpressible()" because "booleanExpression" is null

	at org.hibernate.query.sqm.tree.predicate.SqmBooleanExpressionPredicate.<init>(SqmBooleanExpressionPredicate.java:38)
	at org.hibernate.query.sqm.tree.predicate.SqmBooleanExpressionPredicate.<init>(SqmBooleanExpressionPredicate.java:31)
	at org.hibernate.query.sqm.internal.SqmCriteriaNodeBuilder.wrap(SqmCriteriaNodeBuilder.java:497)
	at org.hibernate.query.sqm.tree.select.SqmQuerySpec.setRestriction(SqmQuerySpec.java:362)
	at org.hibernate.query.sqm.tree.select.AbstractSqmSelectQuery.where(AbstractSqmSelectQuery.java:315)
	at org.hibernate.query.sqm.tree.select.SqmSelectStatement.where(SqmSelectStatement.java:373)
	at org.hibernate.query.sqm.tree.select.SqmSelectStatement.where(SqmSelectStatement.java:46)
	at org.hibernate.bugs.MatchAllSpecificationBugTest.findWithCriteriaBuilder(MatchAllSpecificationBugTest.java:86)
	at org.hibernate.bugs.MatchAllSpecificationBugTest.specificationWhereNull_criteriaBuilder(MatchAllSpecificationBugTest.java:56)

Argument of Specification#where(Specification<T>) is marked as @Nullable so I thought this should have worked.

Also, using this specification with a JpaRepository / JpaSpecificationExecutor (taskRepository.findAll(Specification.where(null))) seems to work fine as a "match all" query.

Also, I found a workaround:

Specification<Task> matchAllSpecification = (root, query, cb) -> cb.conjunction();

I have created a minimal Maven project with tests to reproduce the bug : https://github.com/loic-brtd/hibernate-bug-specification-to-predicate.

I'm using :

• org.springframework.data:spring-data-jpa:3.4.1
• org.hibernate.orm:hibernate-platform:6.6.4.Final

[mp911de]

Specification.toPredicate(…) can return null, however, when your code directly evaluates toPredicate(…) then you should include a null check to avoid calling CriteriaQuery .where(null) as the JPA API doesn't accept null predicates (as indicated by the error message).

toPredicate(…) isn't intended to be called from application code, rather it's the SPI side for our executors.