jsf - foreign key in datatable

Question

I'm showing a list of Orders in a datatable , and one of its columns must show the customer_id of that order: customer_id is a fk in ManyToOne relationship.

Customer entity

@Entity
public class Customer {

    ///other columns

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

Order entity

    @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;

and finally, this is the page where i'm putting the datatable with all the orders.

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>

Problem is, everything is fine except the customer_id, which doesn't show on the page. What am I do wrong? I've tried looot of things, changed type of fetching, changed the relationships...but i'm start to thinking it's a java problem , even if i can't really find the solution or some explanation about it on the internet. Could someone help me? I'm stuck :/

Answer 1

I'm happy to say I found the solution! (kudos for @Mauricio Gracia to enlight my finding-a-solution path)

First, I removed the "fetch = FetchType.LAZY" from the customer relationship in Order class

@ManyToOne(cascade={CascadeType.PERSIST})
@JoinColumn(name = "customer_id") 
private Customer customer;

Then, I serialized the Customer class

   @Entity
public class Customer implements Serializable {

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

And everything works fine, I can see the customer id in my .xhtml page :)) However, I don't know if this is a good practice but I think I can take the risk in a small university project like this! Thanks to everyone

Answer 2

Since your Order is related to a Customer here is what you need to do to still use LAZY loading but be able to initilize the customer of a given order

        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();

Also check that you have the set and get related to the customer_id JOIN

Customer getCustomer() { }
setCustomer(Customer cust) { }