java - 如何将 native 查询的结果集映射到实体中的变量

Question

我有两个实体:用户和注释，我想将注释表上的查询的一组结果添加到用户实体中的 transient 变量。

实体:

用户

@Entity
public class Users {
    @Id
    @GeneratedValue
    @Column(name="user_id")
    private Long userId;

    @Column(name="username", unique=true, nullable=false)
    private String username;

    @Transient
    private Set<Annotation> annotations;
    .....

注释

@Entity
@Table(name="Annotation")
public class Annotation {

    @Id
    @GeneratedValue
    @Column(name="anno_id")
    private Long annoId;

    @Column(name="user_id", nullable=false)
    private Long userId;

    @Enumerated(EnumType.STRING)
    @Column(name="access_control", nullable=false)
    private Access accessControl;

    @Column(name="group_id", nullable=true)
    private Long groupId;
    .....

所以我想要Set<Annotation> annotations用于保存注释表查询结果的变量。这不能简单地是一对多映射，因为我必须以特定方式限制结果。事实上，查询是这样的:

SELECT anno_id, a.user_id, timestamp, is_redacted, access_control, a.group_id, vocabulary_id, key_, value, target_type, target_id, root_type, root_id FROM Annotation AS a 
LEFT JOIN group_membership g ON g.user_id = ?#{ principal?.getId() }
WHERE a.user_id = :id
AND (a.access_control='PUBLIC'
OR (a.access_control='GROUP' AND a.group_id = g.group_id
OR (a.access_control='PRIVATE' AND g.user_id = a.user_id))
GROUP BY a.anno_id

我认为通过 SQLResultSetMapping 这是可能的，但是，结果似乎总是映射到另一个不同的实体。是否可以将集合提取为集合并以我想要的方式存储它？

Answer 1

在这种情况下您不能使用 SQLResultSetMapping，因为结果只会映射到不同的实体。您可以做的是作为 native 查询执行，然后以对象数组列表的形式获取结果。然后您可以构造所需的对象。

        Query query = entityManager
                .createNativeQuery("SELECT anno_id, a.user_id FROM Annotation AS a"
                        + " LEFT JOIN group_membership g ON g.user_id = ?"
                        + " WHERE a.user_id = ?"
                        + " AND (a.access_control='PUBLIC'"
                        + " OR (a.access_control='GROUP' AND a.group_id = g.group_id)"
                        + " OR (a.access_control='PRIVATE' AND g.user_id = a.user_id))"
                        + " GROUP BY a.anno_id");
        query.setParameter(1, new Long(1));
        query.setParameter(2, new Long(1));
        List<Object[]> list = query.getResultList();
        return list;