Question

执行命令时，EntityManager会抛出（所有https://pastebin.com/zKYBhsv8）

[EL Warning]: 2017-10-14 20:07:55.332--UnitOfWork(402037615)--Exception [EclipseLink-6168] (Eclipse Persistence Services - 2.7.0.v20170811-d680af5): org.eclipse.persistence.exceptions.QueryException
Exception Description: Query failed to prepare, unexpected error occurred: [java.lang.NullPointerException].
Internal Exception: java.lang.NullPointerException
Query: ReportQuery(referenceClass=MovieEntity )

代码看起来像这样

我创建

final CriteriaBuilder cb = this.entityManager.getCriteriaBuilder();
final CriteriaQuery<Long> countQuery = cb.createQuery(Long.class);
final Root<MovieEntity> root = countQuery.from(MovieEntity.class);

然后我创建谓词

final Predicate whereClause = MovieSpecs
            .getFindPredicate(root, cb, countries);

这是方法

public static Predicate getFindPredicate(
        final Root<MovieEntity> root,
        final CriteriaBuilder cb
        final List<CountryType> countries
) {
    final List<Predicate> predicates = new ArrayList<>();
    if(countries != null && !countries.isEmpty()) {
        final List<Predicate> orPredicates =
                countries
                        .stream()
                        .map(status -> cb.equal(root.get(MovieEntity_.countries), countries))
                        .collect(Collectors.toList());
        predicates.add(cb.or(orPredicates.toArray(new Predicate[orPredicates.size()])));
    }
    return cb.and(predicates.toArray(new Predicate[predicates.size()]));
}

然后在countQuery中设置谓词

countQuery.select(cb.count(root)).where(whereClause);

并执行命令

final Long count = this.entityManager.createQuery(countQuery).getSingleResult();

在这里我抛出了上述错误。

MovieEntity：https://pastebin.com/CvhEQFZD MovieEntity_：http s：//pastebin.com/ZyJL0nmM

Answer 1

我认为当EclipseLink尝试处理针对集合完成的countries匹配时会出现问题：

.map(status -> cb.equal(root.get(MovieEntity_.countries), *countries*))

我认为您的目的是检查与流式项目的相等性

.map(status -> cb.equal(root.get(MovieEntity_.countries), status))

Answer 2

假设您希望所有MovieEntities个人拥有一个或多个提供的Countries，您可以尝试将cb.equal(root.get(MovieEntity_.countries), countries)替换为cb.isMember(status, MovieEntity_.countries)。

然而，这可能不是最佳方式，但至少最容易测试您当前的代码。也许您还应该将status更改为country，以使代码更容易理解。

EclipseLink - 查询未能准备，发生意外错误

2 个答案: