java - 带有列表的 JPA CriteriaQuery 投影

Question

我正在尝试使用包装类作为结果类型进行查询。很抱歉发了这么长的帖子，但我想让我的问题尽可能完整。根类有 3 个我要检索的列表:

@Entity
@Table(name = "cash")
public final class Cash extends BaseSimpleModel {
    @Id
    @SequenceGenerator(name = "id", sequenceName = "cash_seq")
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "id")
    private Long cashID;

    @Column(length = 50, unique = true)
    private String description;

    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
    @JoinColumn(name = "cashID")
    private List<CashAllowedValue> allowedValueList;

    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
    @JoinColumn(name = "cashID")
    private List<CashAllowedCurrency> allowedCurrencyList;

    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
    @JoinColumn(name = "cashID")
    private List<CashAllowedCashier> allowedCashierList;
    ... getters and setters
}

这是我的包装类:

public class CashQueryResult extends QueryResult {
    private Long cashID;
    private String description;
    private List<CashAllowedValue> allowedValueList;
    private List<CashAllowedCurrency> allowedCurrencyList;
    private List<CashAllowedCashier> allowedCashierList;

    public CashQueryResult(Long id, String description, List<CashAllowedValue> allowedValueList, List<CashAllowedCurrency> allowedCurrencyList, List<CashAllowedCashier> allowedCashierList)
    {
        this.cashID = id;
        this.description = description;
        this.allowedValueList = allowedValueList;
        this.allowedCurrencyList = allowedCurrencyList;
        this.allowedCashierList = allowedCashierList;
    }
    ... getters
}

这是我的查询:

public final List<CashQueryResult> getQRList(final CashQueryParameter cashQP, final QueryHint queryHint) {
    List<CashQueryResult> cashQRL = null;
    try {
        final CriteriaBuilder cb = em.getCriteriaBuilder();
        final PredicateBuilder pb = new PredicateBuilder(cb);
        final CriteriaQuery<CashQueryResult> cq = cb.createQuery(CashQueryResult.class);
        final Root<Cash> cash = cq.from(getModelClass());

        // Joins.
        final ListJoin<Cash, CashAllowedValue> allowedValueList = cash.join(Cash_.allowedValueList, JoinType.LEFT);
        final ListJoin<Cash, CashAllowedCurrency> allowedCurrencyList = cash.join(Cash_.allowedCurrencyList, JoinType.LEFT);
        final ListJoin<Cash, CashAllowedCashier> allowedCashierList = cash.join(Cash_.allowedCashierList, JoinType.LEFT);

        // Paths.
        final Path<ValueTypeEnum> valueType = allowedValueList.get(CashAllowedValue_.valueType);
        final Path<Currency> currency = allowedCurrencyList.get(CashAllowedCurrency_.currency);
        final Path<IntranetUser> intranetUser = allowedCashierList.get(CashAllowedCashier_.cashier);

        // Expressions. Just for testing purposes.
        final Expression<List<CashAllowedValue>> cashAllowedValueListExpression = cash.get(Cash_.allowedValueList);
        final Expression<List<CashAllowedCurrency>> cashAllowedCurrencyExpression = cash.get(Cash_.allowedCurrencyList);
        final Expression<List<CashAllowedCashier>> cashAllowedCashierExpression = cash.get(Cash_.allowedCashierList);

        cq.distinct(true);
        cq.select(cb.construct(CashQueryResult.class, cash.get(Cash_.cashID), cash.get(Cash_.description),
            // cash.get(Cash_.allowedValueList), cash.get(Cash_.allowedCurrencyList), cash.get(Cash_.allowedCashierList) // does not work
            // cashAllowedValueListExpression, cashAllowedCurrencyExpression, cashAllowedCashierExpression // does not work
            allowedValueList, allowedCurrencyList, allowedCashierList // does not work
        ));

        // cq.multiselect(cash.get(Cash_.cashID), cash.get(Cash_.description),
        //     allowedValueList, allowedCurrencyList, allowedCashierList
        // ); // does not work

        cq.where(cb.and(pb.like(cash.get(Cash_.description), cashQP.getDescription()), pb.equal(valueType, cashQP.getValueType()), pb.equal(currency.get(Currency_.currencyID), cashQP.getCurrencyID()), pb.equal(intranetUser.get(IntranetUser_.agentID), cashQP.getIntranetUserID())));
        cq.orderBy(cb.asc(cash.get(Cash_.description)));

        final TypedQuery<CashQueryResult> tq = em.createQuery(cq);
        tq.setFirstResult(queryHint.getFirstResult());
        tq.setMaxResults(queryHint.getMaxResults());
        cashQRL = tq.getResultList();
    }
    catch (Throwable t) {
        throw new EJBException(t.getMessage());
    }
    return cashQRL;
}

最后，异常(它根据我尝试的选择方法而有所不同，但它总是这样的):

2011-09-12 16:12:26,165 ERROR [org.hibernate.hql.PARSER] (http-127.0.0.1-8080-2) Unable to locate appropriate constructor on class [com.ebizlink.adonis.erp.model.support.CashQueryResult] [cause=org.hibernate.PropertyNotFoundException: no appropriate constructor in class: com.ebizlink.adonis.erp.model.support.CashQueryResult]
2011-09-12 16:12:26,169 SEVERE [javax.enterprise.resource.webcontainer.jsf.context] (http-127.0.0.1-8080-2) javax.ejb.EJBException: org.hibernate.hql.ast.QuerySyntaxException:
Unable to locate appropriate constructor on class [com.ebizlink.adonis.erp.model.support.CashQueryResult]
[select distinct new com.ebizlink.adonis.erp.model.support.CashQueryResult(generatedAlias0.cashID, generatedAlias0.description, generatedAlias1, generatedAlias2, generatedAlias3)
 from com.ebizlink.adonis.erp.model.Cash as generatedAlias0
    left join generatedAlias0.allowedValueList as generatedAlias1
    left join generatedAlias0.allowedCurrencyList as generatedAlias2
    left join generatedAlias0.allowedCashierList as generatedAlias3
 where ( 1=1 ) and ( 1=1 ) and ( 1=1 ) and ( 1=1 )
 order by generatedAlias0.description asc]

作为引用，这里是 PredicateBuilder万一。我在网上搜索但找不到有人试图检索许多列表。我错过了一些明显的东西吗？多次提取是不行的( hibernate 错误)，而且我也无法将列表设为 Eager。

另一个相关问题是:我可以这样查询，我的包装器类的列表也是实体包装器而不是实体吗？ (例如:不使用 Cashiers，只获取名字和姓氏，并使用包含两个字符串的 CashierWrapper 列表)

非常感谢你，希望你能帮助我。

Answer 1

很可能你不能这样做，规范对构造函数表达式的参数说了什么:

constructor_expression ::= NEW constructor_name ( constructor_item {,constructor_item}* ) constructor_item ::= single_valued_path_expression | scalar_expression | aggregate_expression | identification_variable

并且您尝试提供给构造函数的列表 (collection_valued_field) 不是任何 constructor_item。