實體映射：-分離的實體傳遞給持久化

Question

我正在嘗試保存對象，但出現以下錯誤

org.hibernate.PersistentObjectException: detached entity passed to persist: com.tets.ditacedentity.entity.Department

通過使用CascadeType.MERGE我得到了解決方案，但我想對要使用CascadeType.ALL保存實體的問題使用CascadeType.ALL 。 請任何人告訴我解決方案。謝謝。

用戶實體類：

@Entity
@Table(name = User.TABLE_NAME, indexes = { @Index(columnList = User.COLUMN_USER_ID, unique = true) })
public class User {
    public static final String TABLE_NAME = "User";
    public static final String COLUMN_USER_ID = "pk_user_id";
    public static final String COLUMN_USER_FNAME = "user_fname";
    public static final String COLUMN_USER_EMAIL = "user_email";

    public static final String DEPARTMENT_FOREIGN_KEY = "fk_department";

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = COLUMN_USER_ID)
    private int userId;

    @Column(name = COLUMN_USER_FNAME, columnDefinition = "VARCHAR(255)")
    private String userName;

    @Column(name = COLUMN_USER_EMAIL, columnDefinition = "VARCHAR(255)")
    private String userEmail;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = DEPARTMENT_FOREIGN_KEY, foreignKey = 
    @ForeignKey(name = DEPARTMENT_FOREIGN_KEY))
    private Department dept;

    //Getter Setter

}

部門實體類別：-----

@Entity
@Table(name = Department.TABLE_NAME, indexes = { @Index(columnList = Department.COLUMN_DEPARTMENT_ID, unique = true)})
public class Department {
    public static final String TABLE_NAME = "Deepartment";
    public static final String COLUMN_DEPARTMENT_ID = "dept_id";
    public static final String COLUMN_DEPARTMENT_NAME = "user_fname";


    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = COLUMN_DEPARTMENT_ID)
    private Integer deptId;

    @Column(name = COLUMN_DEPARTMENT_NAME, columnDefinition = "VARCHAR(255)")
    private String deptName;

//Getter setter
}

服務Impl類（業務邏輯）

public void save(User user) {

    if(user.getDept()!=null)
    {
        Department dept = deptRepo.findOne(user.getDept().getDeptId());
        if(dept==null)
        {
            dept = deptRepo.save(user.getDept());
        }
        user.setDept(dept);
    }
    UserRepository.save(user);  

    }

Answer 1

該文檔說CascadeType.ALL等效於

cascade={PERSIST, MERGE, REMOVE, REFRESH, DETACH}.

您可以只選擇您真正想要使用的類型，如下所示：

@Cascade(cascade={CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE})

遵循文檔： https : //docs.oracle.com/javaee/6/api/javax/persistence/CascadeType.html

Answer 2

您最有可能傳遞已在已關閉的事務中獲取的實體：

public void save(User user)

嘗試先合並傳遞的用戶，然后處理結果：

mergedUser = UserRepository.merge(user) // calls session.merge(user) inside

if(mergedUser .getDept()!=null)
{
    Department dept = deptRepo.findOne(mergedUser .getDept().getDeptId());
    if(dept==null)
    ...