HIbernate Annotations - criteria query - loading lazy properties fail

Question

I'm trying to associate 2 classes as below

the code sample for description is as below Bill Class

public class Bill {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO )
    private long id;
    private long billNumber;
    private BillType billType;
    @OneToOne
    private Customer billCustomer;

//getter and setter omitted
}

and definition of customer class is

public class Customer {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    private String customerRef;
    @OneToMany(fetch = FetchType.EAGER)
    private List<Bill> customerBills;}

when i try to retrive the object with criteria API, the associated objects are retrived.

Bill bill = (Bill) session.createCriteria(Bill.class)
                .add(Restrictions.eq("billNumber", BILL_NUMBER)).uniqueResult();

when i validate the size of the bills associated with an customer, it retrived as null. (but 1 bill is associated to customer)

Assert.assertEquals(1,bill.getBillCustomer().getCustomerBills().size());

(the above condition fails), but when i validate with other way around, it succeeds

List<Bill> billList = session.createCriteria(Customer.class)
                .add(Restrictions.eq("customerRef",CUSTOMER_REF)).list();
        Assert.assertEquals(1,billList.size());

I eagerly loaded the objects. i can't figure out what i'm missing?

JB Nizet · Accepted Answer · 2012-09-10 13:01:02Z

1

Your mapping is wrong. If the association is a one-to-many bidirectional association, one side must define it as OneToMany, and the other side as ManyToOne (not OneToOne).

Moreover, a bidirectional association always has an owner side and an inverse side. The inverse side is the one with the mappedBy attribute. In the case of a OneToMany, the inverse side must be the one side. So the mapping should be:

@ManyToOne
private Customer billCustomer;

...

@OneToMany(fetch = FetchType.EAGER, mappedBy = "billCustomer")
private List<Bill> customerBills;

This mapping is described in the hibernate documentation.

answered Sep 10, 2012 at 13:01

JB Nizet

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