在填充的数据库中使用@GeneratedValue（strategy = GenerationType.IDENTITY）会导致PK约束错误

Question

I'm trying to add FeedbackItem items to my database. The general idea is that an existing object of type Group can receive multiple FeedbackItem objects. Afterwards I update the object:

groupDAO.startTransaction();
groupDAO.update(selectedGroup);
groupDAO.commitTransaction();

//in groupDAO
public T update(T entity){
   return em.merge(entity);
}

I'm not suring whether it is JPA causing the issue or not, but the following error will appear:

Internal Exception: java.sql.SQLIntegrityConstraintViolationException: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'SQL170430012202680' defined on 'FEEDBACKITEM'.

After some more debugging I found the following entries:

[EL Fine]: sql: 2017-04-30 01:22:14.977-- #### VALUES (?, ?) bind => [sampleText, 2]

[EL Fine]: sql: 2017-04-30 01:22:14.997--ClientSession(889348271)--Thread(Thread[JavaFX Application Thread,5,main])--VALUES(1)

Does VALUES(1) mean that it's trying to insert the object under the ID 1? It's the only lead I currently have. My database is populated with 10 entries, having an ID ranging from 1 to 10.

Below is the class I'm trying to persist to the database:

@Entity
public class FeedbackItem implements Serializable{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int feedbackId;

    private String feedback;

    @ManyToOne(cascade = CascadeType.PERSIST)
    private User ownerFeedback;

    protected FeedbackItem(){

    }
}

I tested my code without @GeneratedValue(strategy=GenerationType.IDENTITY) and assigned ID's manually. This works without any issues.

EDIT: below is the Group entity:

@Entity
public class Group implements IReadOnlyGroup {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int groupId;
    private String name;

    @OneToMany(mappedBy = "group")
    private List<Action> actions;

    @OneToMany(cascade = CascadeType.PERSIST)
    private List<Proposal> proposals;

    @OneToMany(mappedBy = "group")
    private List<Motivation> motivations;

    @OneToOne(mappedBy = "group")
    private GroupState currentState;

    public Groep() {
    }
}

The Group object contains the FeedbackItem objects indirectely. Each Proposal stores one FeedbackItem

Entity
public class Proposal {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Temporal(TemporalType.TIMESTAMP)
    private Date date = null;

    @ManyToMany
    private List<Action> actions;

    @OneToOne
    private FeedbackItem feedbackitem;

    boolean approved;

    protected Proposal() {

    }

    public Proposal ( List<Action> actions, String feedback, boolean approved, User owner){
        this.date = new Date();
        this.actions = actions;
        this.approved = approved;
        this.feedbackitem = new FeedBackItem(feedback, owner);
    }
}

Answer 1

@OneToMany(cascade = CascadeType.PERSIST) 
private List<Proposal> proposals;

Means that Proposal entities are persisted together with Group, but not merged. Other entities should be persisted separately before assigning and persisting Group entity. I would try remove this cascade attribute, and check if problem still exists.