Question

无法为我的spring data jpa查询使用自定义POJO类。反复失败，但出现以下异常

“ org.hibernate.MappingException：未知实体： com.app.mycompany.AgileCenterServices.entities.ComponentDetailedInfo“ *

试图替换自定义的ComponentDetailedInfo.class并在对EntityManager .createNativeQuery(componentQuery.toString())的调用期间未提及任何内容，但随后返回的对象列表在查询后无法转换为特定的POJO类。

@Override
public ComponentListResponsePaginated findComponentByProjectId(String projectId, Pageable pageable) { 

logger.info(" Inside findComponentByProjectId() API in IssueComponentServiceImpl");

String componentQuery = "select c.*, u.fullname "
    + "from issue_component c "
    + "left join user u on c.component_lead = u.username "
    + "where "
    + "upper(c.project_id) = upper(" + projectId + ")";

List<ComponentDetailedInfo> compList = new ArrayList<ComponentDetailedInfo>();

try {

logger.info(" ************* Printing query ******************************* ");
logger.info(componentQuery.toString());

compList = entityManager.createNativeQuery(componentQuery.toString(), ComponentDetailedInfo.class)            .setFirstResult(pageable.getOffset())
.setMaxResults(pageable.getPageSize())
.getResultList();

}

}

也尝试了以下方法

List<? extends Object> objList = null;

objList = entityManager.createNativeQuery(componentQuery.toString())              .setFirstResult(pageable.getOffset())
.setMaxResults(pageable.getPageSize())
.getResultList();

if(objList != null && objList.size() > 0) {
    for(Object rec: objList) {
       logger.info(" Printing Object ::: " + rec.toString());
       compList.add((ComponentDetailedInfo)rec);
    }
}

但是compList失败

java.lang.ClassCastException

返回的自定义查询应类型转换为传递给EntityManager .createNativeQuery的特定类类型。但是，当我将类传递给createNativeQuery()时，遇到了上面提到的异常。

甚至尝试过完全删除createNativeQuery中的类...

Answer 1

如果要作为本机查询的结果使用POJO，则必须定义构造函数结果映射。

这是一个示例查询：

Query q = em.createNativeQuery(
    "SELECT c.id, c.name, COUNT(o) as orderCount, AVG(o.price) AS avgOrder " +
    "FROM Customer c " +
    "JOIN Orders o ON o.cid = c.id " +
    "GROUP BY c.id, c.name",
    "CustomerDetailsResult");

这就是您必须添加到实体的映射：

@SqlResultSetMapping(name="CustomerDetailsResult",
    classes={
        @ConstructorResult(targetClass=com.acme.CustomerDetails.class,
            columns={
                @ColumnResult(name="id"),
                @ColumnResult(name="name"),
                @ColumnResult(name="orderCount"),
                @ColumnResult(name="avgOrder", type=Double.class)})
    })

如果您不喜欢这种方法，可以使用QLRM。在此处了解更多信息：https://github.com/simasch/qlrm

Spring Data JPA自定义查询无法识别类类型

1 个答案: