Question

我正在使用JPA查询来获取结果集，然后在同一个类中，我想有条件地获取更多数据。这是它的样子：

public SchoolUser getCandidatesAsJson(@PathParam("applicationId") String applicationId, @PathParam("userPassword") String userPassword ) {

    EntityManager em = createEM();

    Query query = em.createQuery("SELECT su FROM SchoolUser su WHERE su.applicationId LIKE :applicationId and su.userPassword LIKE :userPassword", SchoolUser.class);

    query.setParameter("applicationId", applicationId);
    query.setParameter("userPassword", userPassword);


    List <SchoolUser> schoolUser = query.getResultList();

    if(!schoolUser.isEmpty()) {

        SchoolUser loginRecord = schoolUser.get(0);

        int teacherId = loginRecord.getTeacherId();
        int studentId = loginRecord.getStundentId();

        if(teacherId!=0){

            TypedQuery<Classroom> query2 = em.createQuery("SELECT c FROM Classroom c where c.teacherId = :teacherId ORDER BY c.period", Classroom.class);

            query2.setParameter("teacherId", teacherId);

            List <Classroom> teacherClassList = query2.getResultList();

            if(!teacherClassList.isEmpty()){

                                    //put 2nd results set in SchoolUser object - line is commented because it causes an erro
                //loginRecord.setClassRooms(teacherClassList);

            } 

        } else if(studentId!=0){


            TypedQuery<ClassroomStudent> query3 = em.createQuery("SELECT cs FROM ClassroomStudent cs where cs.statusId = 1 AND cs.studentId = :studentId", ClassroomStudent.class);
            query3.setParameter("studentId", studentId);

                            //put results in SchoolUser object

        }



        return loginRecord;

    } else {

        SchoolUser emptyRecord = new SchoolUser();

        return emptyRecord;
    }



}

错误来自将Classroom JPA对象放入SchoolUser对象 - 因为这两个对象没有直接关系。

我可以通过JPA以任何方式完成此任务吗？

Answer 1

如果您不想保留classroom（或该问题的任何其他属性），则@Transient注释允许您忽略特定字段，以便JPA不会尝试映射它。

此注释指定属性或字段不是执着。它用于注释实体的属性或字段 class，mapping superclass或embeddable class。

Example:
@Entity
public class Employee {
    @Id int id;
    @Transient User currentUser;
    ...
}

使用JPA返回两个结果集

1 个答案: