TopLink EntityManager不能正確保存對象

Question

真的很感謝任何幫助（至少如何跟蹤問題的根本原因），因爲我已經與此戰鬥了好幾天，甚至找不到解決方法。這個問題本身：我有一些實體，它們都工作得很好 - persist（），find（）等等，除了一個創建兩個不同實體的方法（Order和Items，一個Order可以有很多Items） 。在調用em.persist（..）命令被保存後，我看到它的數據庫生成的ID，項目被保存到數據庫（我通過直接在數據庫中看到它），但它顯示ID = 0。無論我做什麼，它總是0（例如，當我打開訂單，我仍然看到它的ID = 0），直到我重新啓動服務器 - 然後它顯示項目的正確ID。該方法的 代碼（後登錄我加入的實際值我得到）：

public void createOrderFromItems(ArrayList<TehnomirItemDTO> items, User user) { 

    Order ord = new Order(); 
    User managers = getUserByEmail(Constants.ALL_MANAGERS_GROUP); 
    ord.setAssignedTo(managers); 
    Date date = new Date(); 
    ord.setCreatedOn(date); 
    User customer = user; 
    ord.setCustomer(customer); 

    BigDecimal custBalance = new BigDecimal(0); 
    ArrayList<Balance> balances = getBalanceForUser(customer); 
    for (Balance b:balances) { 
     custBalance.add(b.getAmount()); 
    } 
    logger.debug("before1. order: "+ord.getOrderId()); //here I get 0 
    em.persist(ord); 
    logger.debug("before2. order: "+ord.getOrderId()); //still 0 

    State new_state = getStateByName(SharedConstants.STATE_NEW); 
    logger.debug("before3. order: "+ord.getOrderId()); //here I get actual ID, generated by DB, e.g. 189 
    State overpriced = getStateByName(SharedConstants.STATE_LIMIT_EXCEEDED); 
    ArrayList<Item> itemList = new ArrayList<Item>(); 
    for (TehnomirItemDTO tid:items) { 
     Item item = new Item(tid); 
     item.setOrder(ord); 
     logger.debug("order inside2:"+ord.getOrderId()); //again, actual ID 

     item.setPriceInt(tid.getPrice_int()); 
     custBalance = custBalance.subtract(item.getPriceInt()); 
     if (custBalance.floatValue()>0) { 
      item.setStateBean(new_state); 
     } else item.setStateBean(overpriced);  
     logger.debug("item before:"+item.getItemId()); //here I get 0 
     em.persist(item); 
     item = em.merge(item); 
     em.setFlushMode(FlushModeType.COMMIT);//added just in case it would work but it didn't 
     em.flush();//same as previous line 

     Item tst = getItemByID(1); 
     logger.debug("item after:"+item.getItemId()+" ord:"+ord.getOrderId()); //again, orderID is correct, itemID is 0 
     itemList.add(item); 
    } 
    ord.setItems(itemList); 

    State new_state2 = getStateByName(SharedConstants.STATE_NEW); 
    logger.debug(ord.getItems().get(0).getItemId()+" order: "+ord.getOrderId());//again, orderID is correct, itemID is 0 
} 

Order類：

@Entity 
@Table(name="orders") 
public class Order implements Serializable { 
    private static final long serialVersionUID = 1L; 

    @Id 
    @GeneratedValue(strategy=GenerationType.IDENTITY/*,  generator="ORDERS_ORDERID_GENERATOR"*/) 
    @Column(name="ORDER_ID") 
    private int orderId; 

    @Temporal(TemporalType.TIMESTAMP) 
    @Column(name="CREATED_ON") 
    private Date createdOn; 

    //bi-directional many-to-one association to Item 
    @OneToMany(mappedBy="order") 
    private List<Item> items; 


    //uni-directional many-to-one association to User 
    @ManyToOne 
    @JoinColumn(name="ASSIGNED_TO") 
    private User assignedTo; 

    //uni-directional many-to-one association to User 
    @ManyToOne 
    @JoinColumn(name="CUSTOMER") 
    private User customer; 

    public Order() { 
    } 

    public int getOrderId() { 
     return this.orderId; 
    } 

} 

項目類（去除getter和setter方法，使其更具可讀性）： @Entity @Table（name =「items」） public class Item implements Serializable {private static final long serialVersionUID = 1L;

@Id 
    @Column(name="ITEM_ID") 
    private int itemId; 

    private String code; 

    private BigDecimal weight; 

    public BigDecimal getWeight() { 
     return weight; 
    } 

    public void setWeight(BigDecimal weight) { 
     this.weight = weight; 
    } 

    private String comments;//any additional info user'd like to add 

    private String description; 

    @Column(name="EXT_ID") 
    private int extId; 

    private String manufacturer; 

    @Column(name="PRICE_EXT") 
    private BigDecimal priceExt; 

    @Column(name="PRICE_INT") 
    private BigDecimal priceInt; 

    private String region; 

    private String term; 

    //bi-directional many-to-one association to Order 
    @ManyToOne(cascade=CascadeType.PERSIST) 
    @JoinColumn(name="ORDER_ID") 
    private Order order; 

    //bi-directional many-to-one association to State 
    @ManyToOne 
    @JoinColumn(name="STATE") 
    private State state; 

} 

我有一些想法有關緩存，所以我說我的persistence.xml線

property name="toplink.cache.type.default" value="NONE" 
property name="toplink.cache.type.Order" value="NONE" 

，但它並沒有幫助

Answer 1

嘗試改變int到Integer

private Integer orderId; 

以及吸氣劑和吸附劑。

Answer 2

你提到的Item被數據庫分配了一個ID值，但是錯過了你訂購的@GeneratedValue（strategy = GenerationType.IDENTITY）註釋。這是告訴JPA db控制的值，否則它期望應用程序將其設置爲默認值0.

Answer 3

調用em.persist（obj）後，調用em.flush（）;.它應該工作。

最好有保存 像

private void save(object obj) 
{ 
    em.persist(obj); 
    em.flush(); 
}