java - 如果 ID 已存在，则将实体与另一个实体一起保存为属性时出错

Question

我有两个实体。

@Entity
@Table(name = "OPERATORS_REPORT_TABLE")
@NamedQuery(name = "OperatorsReportTable.getAll", query = "SELECT c from OperatorsReportTable c")
public class OperatorsReportTable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    @Column(name = "OPERATOR_FIO", length = 2000)
    private String operator_fio;
    @Column(name = "NICKNAME", length = 500)
    private String nickname;
    @Column(name = "OPERATOR_AVAYA_ID", length = 4)
    private int operator_avaya_id;
    @OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinColumn(name = "LANGUAGES_LIST_ID")
    private LanguagesList languagesList;

和

@Entity
@Table(name = "LANGUAGES_LIST")
@NamedQuery(name = "LanguagesList.getAll", query = "SELECT c from LanguagesList c")
public class LanguagesList {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    @Column(name = "LANGUAGE_NAME", length = 2000)
    private String languageName;

我填写DB的LanguagesList。我从 Web 表单创建了 OperatorsReportTable。例如我有表

id language
0   eng 
1   ru

我在数据库中手动填写。

我有第二张 table

id operator_fio nickname operator_avaya_id LANGUAGES_LIST_ID
0   name 1      nickname1  1111             1
1   name 2      nickname2  2222             2

如果我也在数据库中手动创建 operatr - 一切正常。但我无法从代码创建这个实体:

public void insertNewOperator(OperatorsReportTable newOperator) {
        em.getTransaction().begin();
        try {
            em.persist(newOperator);
        } catch (Exception e) {
            logger.log(Level.FINEST, "Exception in  task time={0}. Exception message = {1}.", new Object[]{newOperator.getNickname(), e.getMessage()});
        }
        try {
            em.getTransaction().commit();
            em.clear();
        } catch (Exception e) {
            logger.log(Level.FINEST, "Exception in  task time={0}. Exception message = {1}.", new Object[]{new Date(), e.getMessage()});
            em.clear();
        }
    }

我有错误:

org.hibernate.PersistentObjectException: detached entity passed to persist: entety.LanguagesList

我认为这是因为语言表条目已经存在。我需要创建新的运算符并从语言表中设置 iD 并保存它。

Answer 1

如果您想保存 OperatorsReportTable 对象而不保存 LanguagesList 对象(因为它已经保存了)，那么您必须使用 @ManyToOne

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "LANGUAGES_LIST_ID")
private LanguagesList languagesList;

此外，删除级联。