使用休眠獲取更新的行在一對多映射

Question

我有兩個實體Issue和Issue_Tracker。我已經以一對多的方式加入了這張桌子。在Issue_Tracker，我們可以有一個像

issue_id tracker_status  tracked_time 
    123  Assigned   1/8/2013 11:44 
    123  Assigned   1/8/2013 11:45 
    123  Completed   1/8/2013 11:52 
    32  Assigned   1/9/2013 16:46 
    33  Assigned   1/9/2013 16:47 
    33  Cancel    1/9/2013 16:49 

多個條目我要訂購由tracked_time的Issue_tracker實體，所以我可以tracker_status。我現在用的標準得到的數據只有最後一次更新，但我得到的第一個條目例如：對於issue_id 123，我將tracker_status設爲Assigned，但我想爲id 123獲取tracker_status : Completed。如何實現此目的。吾道如下

 Criteria criteria = session.createCriteria(Issue.class); 
    criteria.setFirstResult(from); 
    criteria.setMaxResults(size); 
    criteria.setFetchMode("Issue.issueTracker",FetchMode.JOIN); 
    criteria.add(Restrictions.eq("status", "Escalate To")); 
     return criteria.list(); 

Issue.java

public class Issue implements Serializable 
     { 
     private Integer issue_id; 
     private String issue_description; 
     private Date issue_raised_date; 
     private Set<Issue_Tracker> issueTracker = new HashSet<Issue_Tracker>(0); 



     @OneToMany(fetch=FetchType.LAZY, mappedBy="issue_id") 
     public Set<Issue_Tracker> getIssueTracker() { 
     return issueTracker; 
    } 

     public void setIssueTracker(Set<Issue_Tracker> issueTracker) { 
     this.issueTracker = issueTracker; 

Issue_Tracker.java

public class Issue_Tracker implements Serializable 
{ 
    private Integer issue_id; 
    private String tracker_status; 
    private Timestamp tracked_time; 

我希望你們能得到什麼，我想問問，任何幫幫我？

Answer 1

將@OrderBy批註添加到映射集合中。這應該返回按跟蹤時間排序的集合中的實體。該集合中的第一個實體應該是最新的。

//Issue.java 
    @OneToMany(fetch=FetchType.LAZY, mappedBy="issue_id") 
    @OrderBy("tracked_time DESC") 
    public Set<Issue_Tracker> getIssueTracker() { 
    return issueTracker; 

你也可以試試：

Criteria criteria = session.createCriteria(Issue.class); 
criteria.setFirstResult(from); 
criteria.setMaxResults(size); 
criteria.setFetchMode("Issue.issueTracker",FetchMode.JOIN); 
criteria.add(Restrictions.eq("status", "Escalate To")); 
Criteria subCriteria = criteria.createCriteria("issueTracker"); 
subCriteria.addOrder(Order.desc("tracked_time")); 
return criteria.list();