Question

非常感谢任何帮助（至少如何追查问题的根本原因），因为我已经和它斗争了好几天，甚至找不到解决方法。

问题本身：我有一些实体，它们都运行良好 - persist（），find（）等，除了一种方法，我创建两个不同的实体（订单和项目，一个订单可以有很多项目）。在调用em.persist（..）后，命令被保存，我看到它由DB生成的id，项目被保存到DB（我直接在DB中通过SELECT看到它），但它显示ID = 0。无论我做什么它总是0（例如，当我打开订单时，我仍然看到它的ID = 0），直到我重新启动服务器 - 然后它显示正确的项目ID。方法代码（记录后我添加了实际值）：

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
}

订单类：

@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;
    }

}

项目类（删除了getter和setter以使其更具可读性）： @实体 @table（名称= “项目”。） public class Item实现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;

}

我对缓存有一些想法，所以我添加到了persistence.xml行

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

但它没有任何帮助

Answer 1

尝试将int更改为Integer

private Integer orderId;

以及吸气剂和制定者。

Answer 2

您提到项目由数据库分配了ID值，但错过了订购时的@GeneratedValue（strategy = GenerationType.IDENTITY）注释。这是告诉JPA db控制值的原因，否则它期望应用程序设置它，使其保持默认为0.

Answer 3

调用em.persist（obj）后，调用em.flush（）;.它应该工作。

更好的私有方法保存喜欢

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

TopLink EntityManager无法正确保存对象

3 个答案: