Question

任何人都有如何仅在辅助表中保留值的示例吗？

@Entity
@Named("account")
@Table(name = "ACCOUNT", uniqueConstraints = {})
@SecondaryTables({ @SecondaryTable(name = "ACCOUNTCOMMENT", pkJoinColumns =   { @PrimaryKeyJoinColumn })) {
...
@Column(table = "ACCOUNTCOMMENT", name = "COMMENTS", unique = false, nullable = true, insertable = true, updatable = true, length = 4000)
public String getComment() {
    return this.comment;
}

public void setComment(String comments) {
    this.comment = comments;
}

@Temporal(TemporalType.TIMESTAMP)
@Column(table = "ACCOUNTCOMMENT", name = "LAST_EDITED", unique = false, nullable = true, insertable = true, updatable = true, length = 7)
public Date getCommentLastEdited() {
    return this.commentLastEdited;
}

public void setCommentLastEdited(Date lastEdited) {
    this.commentLastEdited = lastEdited;
}

@Column(table = "ACCOUNTCOMMENT", name = "LAST_EDITOR_EMPLOYEE_ID", unique = false, nullable = true, insertable = true, updatable = true, length = 10)
public String getCommentLastEditorEmployeeId() {
    return this.commentLastEditorEmployeeId;
}

public void setCommentLastEditorEmployeeId(String lastEditorEmployeeId) {
    this.commentLastEditorEmployeeId = lastEditorEmployeeId;
}

....
}

我正在尝试仅在辅助表（AccountComment）中更新值。我正在使用hibernate 4和JPA2。

尝试以下代码，

@Transactional
public void saveAccountComment() throws SystemException {
    System.out.println("Entered into saveAccountComments method...");
    Account acct = acctInfo.getAccount();
    acct.setComment(accountForm.getCommentText());
    Date lastEdited = new Date();
    acct.setCommentLastEdited(lastEdited);
    Officer lastEditor = utils.getOfficer();
    acct.setCommentLastEditorEmployeeId(lastEditor.getEmployeeId());
    accountForm.setLastEditDate(lastEdited);
    accountForm.setLastEditor(lastEditor.getEmpIdAndFullName());
            em.persist(acct);
}

它不起作用。也没有错误日志。当我调用saveAccountComment()方法时。它只是卡住了。

有人知道如何仅在辅助表中保留值吗？

Answer 1

我找到了解决问题的方法。以下代码有助于保留帐户对象。

@Transactional
public void saveAccountComment() throws SystemException {
 Date lastEdited = new Date();
    Officer lastEditor = utils.getOfficer();
    accountForm.setLastEditDate(lastEdited);
    accountForm.setLastEditor(lastEditor.getEmpIdAndFullName());

    Query q = em.createNamedQuery("findAccountByAccountKey").setParameter("accountKey", acctInfo.getAccount().getAccountKey());
    Account account = (Account) q.getSingleResult();
    account.setCommentLastEdited(lastEdited);
    account.setCommentLastEditorEmployeeId(lastEditor.getEmployeeId());
    account.setComment(accountForm.getCommentText());
    em.persist(account);
}

而不是持久保存Account对象，而不是直接传递id（在我的案例中为帐户密钥）并检索对象并设置值并保持不变。

Answer 2

由于可以将多个独立的类映射到同一个表，因此可以将另一个单独的实体类映射到辅助表（id是连接列）。这样，当您只想对辅助表数据进行操作时，可以使用该实体。

但是，无论采用何种方法，您都可能需要重新考虑当前的设计。如果需要单独处理主表和辅助表，最好不要使用辅助表，而是使用两个单独的关联实体。

仅在辅助表中保留值

2 个答案: