[英]Hibernate criteria of Projection
我有两个与@OneToOne
关系的类: User
和Player
。
用户包含一个播放器:
@Entity
@Table(name = "user")
public class User {
@Column(name = "nickname")
private String nickname;
@OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@JoinColumn(name = "id_player")
private Player player;
//getters and setters...
}
我想只使用nickname
和player
查询用户,而对于player
我并不需要所有属性,我只想要2。
这就是我现在所拥有的:
//Projections for the class User
ProjectionList projectionList = Projections.projectionList();
projectionList.add(Projections.property("id"), "id");
projectionList.add(Projections.property("nickname"), "nickname");
projectionList.add(Projections.property("player"), "player");
Criteria criteria = session.createCriteria(User.class);
criteria.setFirstResult(player.getPvpRank() - 5);
criteria.setMaxResults(11);
criteria.createAlias("player", "p");
criteria.addOrder(Order.asc("p.pvpRank"));
criteria.setProjection(projectionList);
criteria.setResultTransformer(Transformers.aliasToBean(User.class));
我仅获得nickname
, id
和player
,但是如何设置对玩家的投射,只获得player.level
而不是所有属性?
它认为这完全符合您的建议:
projectionList.add(Projections.property("player.level"), "player.level");
首先在User
为JoinColumn表Player
创建别名 , 然后在您的projectionList中引用它 。
Criteria criteria = session.createCriteria(User.class);
criteria.createAlias("player", "p");
projectionList.add(Projections.property("p.level"), "player");
...
criteria.setProjection(projectionList);
criteria.setResultTransformer(Transformers.aliasToBean(User.class));
我希望这可以帮助你。
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