如何通过属性不直接在实体休眠弹簧 JPA 上查找操作

Question

我有三个实体，具有以下关系 实体用户有许多带有连接表的活动(单向关系(，因为我需要关系属性， 规则实体具有许多活动(双向关系(

我可以通过该搜索来自一个特定规则的活动进行查找吗？ 听起来有可能，因为活动有规则，但我不知道如何使用休眠来做到这一点

这是我在两种关系中的代码

编辑：我已经用MySQL进行了测试，我需要的查询是这个

select * from user_activity where user_id = userIdValue and activity_id in (
select id from activity where rule_id = rule_idValue);

如何在 Spring 上使用休眠进行该查询？

用户活动(带有关系属性的连接表(

@Entity
@Table(name="USER_ACTIVITY")
public class JoinedUserActivity {
public JoinedUserActivity() {}
public JoinedUserActivity(JoinedUserActivityId joinedUserActivityId, String fileName) {
this.joinedUserActivityId = joinedUserActivityId;
this.fileName  = fileName;
this.score = 0;
this.lastHint = 0;
}
private String fileName; //user activity filename
@ManyToOne
@JoinColumn(name="ACTIVITY_ID", insertable=false, updatable=false)
private Activity activity;

private Integer score;
private Integer lastHint; 
public Activity getActivity() {
return activity;
}
public void setActivity(Activity activity) {
this.activity = activity;
}
//more set and gets
@EmbeddedId
private JoinedUserActivityId joinedUserActivityId;

// required because JoinedUserAchievments contains composite id
@Embeddable
public static class JoinedUserActivityId implements Serializable {
/**
* 
*/
private static final long serialVersionUID = -9180674903145773104L;

@ManyToOne
@JoinColumn(name="USER_ID")
private User user;
@ManyToOne
@JoinColumn(name="ACTIVITY_ID")
private Activity activity;
// required no arg constructor
public JoinedUserActivityId() {}
public JoinedUserActivityId(User user, Activity activity) {
this.user = user;
this.activity = activity;
}
public JoinedUserActivityId(Integer userId, Integer activityId) {
this(new User(userId), new Activity(activityId));
}
public User getUser() {
return user;
}

public Activity getActivity() {
return activity;
}
public void setUser(User user) {
this.user = user;
}
public void setActivity(Activity activity) {
this.activity = activity;
}
@Override
public boolean equals(Object instance) {
if (instance == null)
return false;
if (!(instance instanceof JoinedUserActivityId))
return false;
final JoinedUserActivityId other = (JoinedUserActivityId) instance;
if (!(user.getId().equals(other.getUser().getId())))
return false;
if (!(activity.getId().equals(other.getActivity().getId())))
return false;
return true;
}
@Override
public int hashCode() {
int hash = 7;
hash = 47 * hash + (this.user != null ? this.user.hashCode() : 0);
hash = 47 * hash + (this.activity != null ? this.activity.hashCode() : 0);
return hash;
}
}
}

用户

@OneToMany(cascade=CascadeType.ALL, mappedBy="joinedUserActivityId.user")
private List<JoinedUserActivity> joinedUserActivityList = new ArrayList<JoinedUserActivity>();

活动没有关于用户的信息，因为是单向的。

现在我的活动规则没有连接表，并且使用以下代码双向连接 活动.java

@JsonIgnore
@ManyToOne
Rule rule;

规则.java

@OneToMany(cascade=CascadeType.ALL, mappedBy="rule")
private List<Activity> ListActivities = new ArrayList<Activity>();

所以。。。在联接表 user_activity 上，是否可以定义一个 findBy 函数来从一个规则返回哪些活动有一个用户？

我已经设法做到了

@Override
JoinedUserActivity findOne(JoinedUserActivityId id);

这将从一个用户返回一个活动 但我不知道如何按规则过滤

Answer 1

不需要您的子查询。您只需要一个联接。

在 JPQL 中：

select distinct jua from JoinedUserActivity jua
where jua.user.id = :userId
and jua.activity.rule.id = :ruleId

或者，使用显式联接：

select distinct jua from JoinedUserActivity jua
join jua.user u
join jua.activity a
join a.rule r
where u.id = :userId
and r.id = :ruleId

现在只需在 Spring-data repositoty 接口中添加您想要的方法，并使用@Query对其进行注释，并将上述查询之一作为值。