休眠只保存複合主鍵中具有父外鍵的子表項

Question

我是休眠初學者& Spring MVC並努力爲我的問題找到正確的解決方案。 我有父表（事件）和子表（投票）。每當從URL接收到數據時，我只想保存子表項。我有在映射關係的麻煩和投入組合鍵工作

以下是我的結構：

create table Events(
Event_ID int(11) NOT NULL AUTO_INCREMENT, 
Event_Name varchar(200) NOT NULL, 
Event_options int(1) NOT NULL, 
Start_TIME timestamp, 
End_time timestamp, 
Active_Status int(1), 
PRIMARY KEY(Event_ID) 
)ENGINE=InnoDB AUTO_INCREMENT=16 
; 

create table Votes(
Event_ID int(11) NOT NULL, 
Voter_MSISDN int(13) NOT NULL, 
Vote_Option int(1), 
PRIMARY KEY(Event_ID,Voter_MSISDN), 
FOREIGN KEY (Event_ID) REFERENCES Events(Event_ID) 
)ENGINE=InnoDB AUTO_INCREMENT=16 
; 

Events.java

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

    @Id 
    @GeneratedValue 
    @Column(name = "Event_ID") 
    private Integer eventId; 

    @Column(name="Event_Name") 
    private String eventName; 

    @Column(name="Event_options") 
    private Integer eventOptions; 

    @Column(name="Start_TIME") 
    private String startTime; 

    @Column(name = "End_time") 
    private String End_time; 

    @Column(name="Active") 
    private Integer status; 

    @OneToMany(mappedBy = "Events") 
    private Set<Votes> votes; 
    //Setter Getters 

} 

Votes.java

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

    public Votes(){}   

    @EmbeddedId 
    private Vote vote; 

    @Column(name = "Vote_Option") 
    private int Vote_Option; 


    @ManyToOne 
    @JoinColumn(name = "Event_ID") 
    private Events events; 

    //setters getters 
} 

投票.java for Composite主鍵通過@Embeddable設置

對於添加事件和添加投票

@Embeddable 
public class Vote implements Serializable{ 

     public Vote(){} 

     @Column(name="Event_ID") 
     private int Event_ID; 

     @Column(name="Voter_MSISDN") 
     private long Voter_MSISDN; 

     //setter getters 
} 

控制器片斷

@RequestMapping(value="/AddEvent") 
    @ResponseStatus(value = HttpStatus.OK) 
    public void AddEvent(@RequestParam(value = "ename", required = true) String ename, 
         @RequestParam (value = "opt") String opt, 
         @RequestParam (value = "stime") String start, 
         @RequestParam (value = "etime") String end, 
         @RequestParam (value = "status") String active){ 

     Events event = new Events(); 
     event.setEventName(ename); 
     event.setEventOptions(Integer.parseInt(opt)); 
     event.setStartTime(start); 
     event.setEnd_time(end); 
     event.setStatus(Integer.parseInt(active)); 

     userDao.saveEvent(event); 
    } 

    @Autowired 
    private Vote vote; 

    @Autowired 
    private Votes votes; 

    @RequestMapping(value="/AddVote") 
    @ResponseStatus(value = HttpStatus.OK) 
    public void AddVote(@RequestParam(value = "eventid",required = true) String eventid, 
         @RequestParam(value="msisdn") String msisdn, 
         @RequestParam(value = "opt")String opt){ 

     logger.info("Received parameters from URL "+eventid+" "+msisdn+" "+opt); 
     vote.setEvent_ID(Integer.parseInt(eventid)); 


     vote.setVoter_MSISDN(Long.parseLong(msisdn)); 

     votes.setVote(vote); 
     votes.setVote_Option(Integer.parseInt(opt)); 

     userDao.saveVotes(votes);   
    } 
} 

DAOImplementation：

@Transactional 
    public void saveEvent(Events event) { 
     // TODO Auto-generated method stub 
     Session session = sessionFactory.getCurrentSession(); 

     session.save(event); 

    } 

    @Transactional 
    public void saveVotes(Votes votes){ 

     Session session = sessionFactory.getCurrentSession(); 

     session.save(votes); 
    } 

每當接收事件數據和被添加事件條目的代碼工作正常。 無法爲投票數據正確編碼。 我想只要從url接收到投票數據就插入數據。我已添加Composite主鍵以確保來自一個用戶（MSISDN）的每個事件的唯一條目。 請建議此模型的正確映射。 也歡迎任何改進建議。

Answer 1

首先，您不需要這個簡單解決方案的組合鍵。

你有一個類：

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

    //.................... 

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "Events") 
    private Set<Votes> votes = new HashSet<>(); 

} 

簡單的只是在其中創建了一種方法，將針對此事件創建一個新的投票。對於例如爲：

public Vote createVote() { 
    Vote vote = new Vote(); 
    vote.setEvent(this); 
    votes.add(vote); 
    return vote; 
} 

然後在您的addVote控制器的方法：

@RequestMapping(value="/AddVote") 
@ResponseStatus(value = HttpStatus.OK) 
public void AddVote(@RequestParam(value = "eventid",required = true) String eventid, 
        @RequestParam(value="msisdn") String msisdn, 
        @RequestParam(value = "opt")String opt){ 

    Event event = userDao.findEvent(eventid); 
    Vote vote = event.createVote(); //This will create a vote for an event. 

    vote.set.... //set your stuff. 
    //It will cascade your vote to an event if you have a cascade sorted correctly as in the example above: cascade = CascadeType.ALL 
} 

只要確保你有你的交易權。這只是一個想法應該如何完成。