Undirectional many to one JPQL select foreign keys - jpa

Question

I read different posts, but I couldnt find a solution that works. I think the OneToMany relation causes the problem. I have to following entities:
// Mandant.class (client)
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
#JoinColumn(name = "FK_MANDANT")
private List<Leistung> leistungen = new ArrayList<>();
// Mitarbeiter.class (employee)
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
#JoinColumn(name = "FK_MITARBEITER")
private List<Leistung> leistungen = new ArrayList<>();
// Kategorie.class (category)
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
#JoinColumn(name = "FK_KATEGORIE")
private List<Leistung> leistungen = new ArrayList<>();
which have undirectional OnetoMany relations. I wrote a method filterLeistungen(...) in the LeistungsRepository.class. Now I want to filter the payments (Leistungen) by vague amount of filters. So I compound the filters with a Stringbuilder to a JPQL-Select.
sb.append("l.mandant = ");
sb.append(mandant.getId());
sb.append(" AND ");
Now I create a query with createQuery().
EntityManager entityManager = PREntityManagerFactory.getInstance().createEntityManager();
RepositoryUtils<List<Leistung>> repositoryUtils = new RepositoryUtils<>();
JpaFunction<List<Leistung>> function = () ->
entityManager.createQuery(sb.toString(), Leistung.class).getResultList();
return repositoryUtils.withoutTransaction(entityManager, function);
But when I execute the query I get the following exception:
Exception in thread "main" java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager:
Exception Description: Problem compiling [SELECT l FROM Leistung l WHERE l.fakturierungsdatum IS NULL AND l.mandant = 1 ORDER BY l.datum].
[64, 73] The state field path 'l.mandant' cannot be resolved to a valid type.
I also tried l.mandant.id or l.fk_mandant.id or l.fk_mandant. I use EclipseLink and a MySQL database. All entities have a primary key called id. Is it possible to filter payments (Leistungen) by foreign keys? The payment doesn't know the other entities, because of the undirectional relation. But on the database, the payment has the foreign key attributes, so it should be possible?

Answer 1

I got a tip in a german forum. With the createNativeQuery() method I'm able to use the database dialect, here MySQL. But I think this isn't a really nice solution, because there is no guarantee for platform independence.