jsf - 数据表中的外键

Question

我在数据表中显示订单列表，其中一列必须显示该订单的 customer_id：customer_id 是多对一关系中的 fk。

客户实体

@Entity
public class Customer {

    ///other columns

    @OneToMany(mappedBy = "cliente", fetch=FetchType.EAGER)
    private List<Order> orders;

订单实体

    @Entity
@Table(name = "orders")

public class Order implements Serializable{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;


    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;


    @Column (nullable = false)
    private String state;

    @Column (nullable = false)
    @Temporal(TemporalType.TIMESTAMP)
    private Calendar openingDate;

    @Column (nullable = true)
    @Temporal(TemporalType.TIMESTAMP)
    private Calendar closingDate;

    @Column (nullable = true)
    @Temporal(TemporalType.TIMESTAMP)
    private Calendar evadingDate;

    @ManyToOne(cascade={ CascadeType.PERSIST, CascadeType.REMOVE },fetch=FetchType.LAZY)
    @JoinColumn(name = "customer_id") 
    private Customer customer;

最后，这是我放置包含所有订单的数据表的页面。

showOrders.xhtml

<h:dataTable id="list" value="#{orderController.orders}"
        var="order">
        <h:column>
            <f:facet name="header">Nome</f:facet>
            <h:commandLink action="#{orderController.findOrder}"
                value="#{order.id}" style="color: orange">
                <f:setPropertyActionListener target="#{orderController.id}"
                    value="#{order.id}" />
            </h:commandLink>
        </h:column>
        <h:column>
            <f:facet name="header">Stato</f:facet>
            <h:outputText value="#{order.state}" />
        </h:column>
        <h:column>
            <f:facet name="header">Data Apertura</f:facet>
            <h:outputText value="#{order.openingDate.time}">
                <f:convertDateTime datestyle="full" type="date" />
            </h:outputText>
        </h:column>
        <h:column>
            <f:facet name="header">Data Chiusura</f:facet>
            <h:outputText value="#{order.closingDate.time}">
                <f:convertDateTime datestyle="full" type="date" />
            </h:outputText>
        </h:column>
        <h:column>
            <f:facet name="header">Data Evasione</f:facet>
            <h:outputText value="#{order.evadingDate.time}">
                <f:convertDateTime datestyle="full" type="date" />
            </h:outputText>
        </h:column>
        <h:column>
            <f:facet name="header">ID Cliente</f:facet>
            <h:commandLink action="#{registerCustomer.detailsCustomer}"
                value="#{order.customer.id}" style="color: orange">
                <f:setPropertyActionListener target="#{registerCustomer.id}"
                    value="#{order.customer.id}" /> 
            </h:commandLink>
        </h:column>

问题是，除了 customer_id 没有显示在页面上之外，一切都很好。我做错了什么？我尝试了很多东西，改变了抓取类型，改变了关系......但我开始认为这是一个 java 问题，即使我真的找不到解决方案或一些解释在网上。有人可以帮我吗？我卡住了：/

Answer 1

由于您的 Order 与 Customer 相关，您需要做的是仍然使用延迟加载但能够初始化给定订单的客户

        session = HibernateUtil.getSessionFactory().getCurrentSession();

        session.beginTransaction();
        ord = (Order) session.get(Order.class, id_order);
        Hibernate.initialize(ord.getCustomer());
        session.getTransaction().commit();
        Customer cust = ord.getCustomer();

还要检查您是否拥有集合并与 customer_id JOIN

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