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

考虑以下映射

@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;
    }
}

我正在尝试使用criteriabuilder一对一地查询VerkoopOrder的BetalingsInformatie列表

    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();

但是，“ betalingsInformatie字段始终为null，（您还可以看到我正在提取VerkoopOrderLijnen的列表，该列表已按要求正确地填充了。我还可以尝试获取betalingsInformatie吗？单独查询服务中的每个betalinginformatie字段，而不是直接从查询结果中查询。

有人有见识吗？请记住，这是使用OpenJPA实现而不是休眠或eclipselink

最佳答案

懒惰的JPA属性可以引发异常，也可以执行应做的事情：加载另一个实体。您没有看到异常->实体必须已加载。 Null可能是正确的结果。请检查您正在加载的特定记录的联接列。我猜没有其他实体是从那里映射的。

关于java - @OneToOne无法通过OpenJPA在C​​riteriaBuilder中获取，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/53636286/