@OneToOne无法通过OpenJPA在C​​riteriaBuilder中获取

Question

Consider following mapping

@Table(
    name = "VerkoopOrder"
)
public class VerkoopOrder implements DatabaseEntity, Auditable {

    @Id
    @Column(
        name = "VerkoopOrderId",
        nullable = false
    )
    @GeneratedValue(
        strategy = GenerationType.IDENTITY
    )
    public Long getVerkoopOrderId() {
        return this.verkoopOrderId;
    }

    @OneToOne(
        fetch = FetchType.LAZY
    )
    @JoinColumn(
        name = "BetalingsInformatieId"
    )
    public BetalingsInformatie getBetalingsInformatie() {
        return this.betalingsInformatie;
    }
}

@Table(
    name = "BetalingsInformatie"
)
public class BetalingsInformatie implements DatabaseEntity, Auditable {
    @Id
    @Column(
        name = "BetalingsInformatieId",
        nullable = false
    )
    @GeneratedValue(
        strategy = GenerationType.IDENTITY
    )
    public Long getBetalingsInformatieId() {
        return this.betalingsInformatieId;
    }

    @OneToOne(
        mappedBy = "betalingsInformatie"
    )
    public VerkoopOrder getVerkoopOrder() {
        return this.verkoopOrder;
    }
}

I'm trying to query a list of VerkoopOrder with the one to one BetalingsInformatie inside with the criteriabuilder

    CriteriaBuilder builder = getEntityManager().getCriteriaBuilder();

    CriteriaQuery<VerkoopOrder> query = builder.createQuery(VerkoopOrder.class);
    Root<VerkoopOrder> verkoopOrder = query.from(VerkoopOrder.class);
    verkoopOrder.fetch(BETALINGSINFORMATIE, JoinType.LEFT);
    Join<VerkoopOrder, VerkoopOrderLijn> verkoopOrderLijnen = verkoopOrder.join(VERKOOPORDER_LIJNEN);
    verkoopOrder.fetch(VERKOOPORDER_LIJNEN);
    query.select(verkoopOrder);
    query.distinct(true);

    PredicateBuilder predicateBuilder = new PredicateBuilder(builder, verkoopOrder);

    predicateBuilder
            .addEqualPredicate(UUID, criteria.getUuid())
            .addEqualPredicate(AANKOPER_ID, criteria.getAankoperId())
            .addEqualPredicate(verkoopOrderLijnen.get(MSISDN), criteria.getMsisdn())
            .addEqualPredicate(STATUS, criteria.getStatus())
            .addEqualPredicate(verkoopOrderLijnen.get(VERVOERCONTRACT).get(VERVOERCONTRACT_ID), criteria.getVervoerContractId())
            .addDateTimeRangePredicate(TIMESTAMP_CREATED, criteria.getTimestampCreatedStart(), criteria.getTimestampCreatedEnd())
            .addDateTimeRangePredicate(TIMESTAMP_UPDATED, criteria.getTimestampUpdatedStart(), criteria.getTimestampUpdatedEnd());

    query.where(predicateBuilder.build());
    query.orderBy(builder.desc(verkoopOrder.get(TIMESTAMP_UPDATED)));

    TypedQuery<VerkoopOrder> typedQuery = getEntityManager().createQuery(query);

    List<VerkoopOrder> verkoopOrders = typedQuery.getResultList();

However the "betalingsInformatie field is always null , (you can also see I'm fetching a list of VerkoopOrderLijnen which is filled in just fine as it should. What else can I try to get the betalingsInformatie ? I'm dreading having to seperate query each betalinginformatie field in a service instead of straight from a query result.

Does anyone have any insights ? Keep in mind this is using the OpenJPA implementation not hibernate or eclipselink

Answer 1

Lazy JPA properties can either raise an exception OR they do what they are supposed to do: Load the other entity. You don't see an exception -> the entity must have loaded. Null is probably the correct result. Please check the join column of the particular record you are loading. I guess that no other entity is mapped from there.