弹簧数据JPA：未找到能够从类型转换的转换器

Question

我正在使用Spring Data JPA。我正在尝试使用Employee从Room Employee Mapping和Inner Join表中获取记录。我想显示Employee表中的特定记录，因此在new map查询中使用了JPQL。

如果我从查询中删除特定记录，我将获得正确的联接结果，但是当我添加具有特定列的新地图时，我将得到以下错误提示

有人可以告诉我我在做什么错吗？

RoomEmployeeMappingRepository

@Repository
public interface RoomEmployeeMappingRepository extends JpaRepository<RoomEmployeeMapping, Integer>{

    @Query("select new map ( emp.sEmpName as sEmpName, emp.sDesignation as sDesignation, "
            + "emp.bIsPaid as bIsPaid , emp.sUnpaidComment as sUnpaidComment) from Employee as emp "
            + "Inner Join RoomEmployeeMapping as roomEmpMapping ON emp.nEmpId=roomEmpMapping.nEmpId "
            + "where roomEmpMapping.nRoomAllocationId=?1 ")
    List<Employee> findByNRoomAllocationId(Integer nRoomAllocationId);
}

错误消息

 "message": "No converter found capable of converting from type [java.util.HashMap<?, ?>] to type [com.spacestudy.model.Employee]",

Answer 1

您应该返回Employe实例，如下所示：

select new com.path.to.Employee( emp.sEmpName as sEmpName, emp.sDesignation as sDesignation, "
        + "emp.bIsPaid as bIsPaid , emp.sUnpaidComment as sUnpaidComment)....

确保使用到Employee类的完全限定路径，并且具有与传递的属性匹配的构造函数。