How to update entity using hibernate

Question

I have entity user:

@Entity
@Table(name = "entity_user")
@AttributeOverride(name = "id", column = @Column(name = "user_id"))
public class User extends BaseObject implements Serializable {

    /**
     * Login, unique
     */
    private String email;

    private String username;

    /**
     * Secret for signing-in
     */
    private String password;

    /**
     * Type of user
     */
    private UserType userType;

    @OneToMany(fetch = FetchType.EAGER, cascade = {CascadeType.ALL})
    @JoinTable(name = "view_user_to_requestSet", joinColumns = {
        @JoinColumn(name = "user_id")}, inverseJoinColumns = {
        @JoinColumn(name = "requestSet_id")})
    private Set<RequestSet> setOfRequesSet = new HashSet<>();

    @OneToMany(fetch = FetchType.EAGER, cascade = {CascadeType.ALL})
    @JoinTable(name = "view_user_to_requestSetCreator", joinColumns = {
        @JoinColumn(name = "user_id")}, inverseJoinColumns = {
        @JoinColumn(name = "requestSet_id")})
    private Set<RequestSet> setOfRequesSetCreator = new HashSet<>();

    @OneToMany(fetch = FetchType.EAGER, cascade = {CascadeType.ALL})
    @JoinTable(name = "view_user_to_userTask", joinColumns = {
        @JoinColumn(name = "user_id")}, inverseJoinColumns = {
        @JoinColumn(name = "userTask_id")})
    private Set<UserTask> setOfUserTask = new HashSet<>();

    public User() {
    }

    .
    .
..... GET AND SET

Base object is: @MappedSuperclass public class BaseObject {

@Id
@GeneratedValue
@Column(name = "entity_id")
private Long id;

/**
 *
 * @return true if the entity hasn't been persisted yet
 */
@Transient
public boolean isNew() {
    return id == null;
}

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

}

The proble is, when I try to UPDATE object, I am getting errors:

Exception in thread "Thread-15" org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [UK_5fa729oayn43ynq4v2y4d9qcn]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement

Caused by: org.hibernate.exception.ConstraintViolationException: could not execute statement

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '5' for key 'UK_5fa729oayn43ynq4v2y4d9qcn'

For update entity I am using:

@Transactional
public void save(User value){
   em.merge(value);
}

I am dont know why I am getting this error, how can I update my object? Thank you for your help.

EDIT: I update:

User u = em.find(persistedType, id); //get user by ID
u.getSetOfRequesSet().add(requestSet); //add one otem to set
userDap.merge(u); //save

That doesn't define HOW you attempt to update an object. Where do you get the object from? em.find() ? query? then is it detached? then you update some field(s) whilst detached? — Neil Stockton
– Neil Stockton, Commented Aug 13, 2016 at 8:19
Is there a transaction including both loading and updating of the user? If not I believe the entity gets detached so that Hibernate maybe does not know any more that it is the same as the one in database. Does it work with such a transaction or if you load the entity before merging in "save"? — mm759
– mm759, Commented Aug 13, 2016 at 8:30
If you just do a find then do an update you have no need to do a "merge", since the objects will be "managed" ... assuming all of that is in a single transaction. What is "requestSet" ? Is it already persistent, or a new object? — Neil Stockton
– Neil Stockton, Commented Aug 13, 2016 at 8:44

asch · Accepted Answer · 2016-08-15 15:11:13Z

5

It looks like your update duplicates entries in the set (em.merge). To prevent the duplication you should merge set explicitly. Do as following.

Add method merge to User:

protected User merge(User other) {
    // Just assign all data members(2 examples here)
    setEmail(other.getEmail());
    ....
    setSetOfRequesSet(other.getSetOfRequesSet());
    ...            
}

Prepare an updated object instance:

User updated = em.find(persistedType, id); //get user by ID
updated.getSetOfRequesSet().add(requestSet); //add one item to set

Update the existing db entity:

User existing = em.find(persistedType, id);
existing.merge(updated);

Not necessary to cal to em.merge after the update, since save will be just done at the end of a transaction.

You can find the explanation here.

edited Aug 15, 2016 at 15:11

answered Aug 13, 2016 at 11:23

asch

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