[英]How to update entity using hibernate
我有实体用户:
@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
基础对象是:@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;
}
}
问题是,当我尝试UPDATE对象时,我收到错误:
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'
对于我使用的更新实体:
@Transactional
public void save(User value){
em.merge(value);
}
我不知道为什么我得到这个错误,我怎么能更新我的对象? 谢谢您的帮助。
编辑:我更新:
User u = em.find(persistedType, id); //get user by ID
u.getSetOfRequesSet().add(requestSet); //add one otem to set
userDap.merge(u); //save
看起来您的更新会复制集合中的条目(em.merge)。 为防止重复,您应该明确合并set。 做如下。
将方法合并添加到用户:
protected User merge(User other) { // Just assign all data members(2 examples here) setEmail(other.getEmail()); .... setSetOfRequesSet(other.getSetOfRequesSet()); ... }
准备更新的对象实例:
User updated = em.find(persistedType, id); //get user by ID updated.getSetOfRequesSet().add(requestSet); //add one item to set
更新现有的db实体:
User existing = em.find(persistedType, id); existing.merge(updated);
更新后无需调用em.merge,因为保存将在事务结束时完成。
你可以在这里找到解释。
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